Internet Draft C. Carroll, F. Quick Document: Verizon Wireless, draft-carroll-dynmobileip-cdma-01.txt Qualcomm Inc. Expires: March 2004 September 2003 Dynamic Mobile IP Key Update for cdma2000(R) Networks Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract The Dynamic Mobile IP Key Update procedure is a secure and efficient mechanism for distributing and updating Mobile IP (MIP) cryptographic keys in cdma2000(R) networks (including High Rate Packet Data which is often referred to as 1xEV-DO). Because the Dynamic Mobile IP Key Update (DMU) procedure occurs at the IP layer directly between the MIP MN and RADIUS or DIAMETER AAA Server, DMU may be used to securely bootstrap the MN-AAA key (and other cryptographic keys) in MIP networks using any Radio Access Network technology. cdma2000(R) is a registered trademark of the Telecommunications Industry Association (TIA). Carroll Expires - March 2004 [Page 1] Dynamic MIP Key Update September 2003 Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [1]. Table of Contents 1. Introduction...................................................3 2. Basic Dynamic MIP Key Update Mechanism.........................3 2.1 RSA Encrypted Key Distribution.............................3 2.2 Shared Mutual Authentication...............................4 2.3 Encrypted Password / Encrypted One-Time Password Authentication.................................................7 3. Dynamic MIP Key Update Advantages over OTASP...................8 4. Detailed DMU Procedure Description and Requirements............9 4.1 RSA Public Key Cryptography................................9 4.2 Other Public Key Algorithms...............................10 4.3 Why no Public Key Infrastructure (PKI)?...................10 4.4 Cryptographic Key Generation..............................10 4.5 MIP_Key_Data Payload......................................11 4.6 RSA Key Management........................................12 4.7 RADIUS AAA Server.........................................13 4.8 MN (Handset or Modem).....................................15 4.9 PDSN / Foreign Agent (FA).................................16 4.10 Home Agent (HA)..........................................17 4.11 DMU Procedure Network Flow...............................18 5. DMU Procedure Failure Operation...............................22 6. cdma2000(R) HRPD/1xEV-DO Support..............................25 6.1 RADIUS/DIAMETER AAA Support...............................25 6.2 MN Support................................................26 6.3 Informative MN_Authenticator Support......................27 7. Security Considerations.......................................28 7.1 Cryptographic Key Generation by the MN....................28 7.2 Man-in-the-Middle Attack..................................28 7.3 RSA Private Key Compromise................................28 7.4 RSA Encryption............................................29 7.5 False Base Station/PDSN...................................29 7.6 cdma2000(R) 1X False MN...................................29 7.7 HRPD/1xEV-DO False MN.....................................29 8. Verizon Wireless - Specific RADIUS Attributes.................29 9. Verizon Wireless Mobile IP Vendor/Organization-Specific Extensions .................................................................30 10. Public Key Identifier and DMU Version........................32 11. Intellectual Property........................................36 12. Conclusion...................................................37 13. Formal Syntax................................................37 14. Appendix - Cleartext-Mode Operation..........................39 Carroll Expires - March 2004 [Page 2] Dynamic MIP Key Update September 2003 1. Introduction The Dynamic Mobile IP Key Update procedure is a secure and efficient mechanism for distributing and updating Mobile IP (MIP) cryptographic keys in cdma2000(R) 1xRTT (1X) [2] and High Rate Packet Data (HRPD) / 1xEV-DO networks [3]. The Dynamic Mobile IP Key Update (DMU) procedure occurs at the IP layer directly between the MIP MN and RADIUS or DIAMETER AAA Server. This procedure is an add-on to the existing Telecommunications Industry Association (TIA) TR-45 Standard IS-835 [4]. DMU, however, may be performed in any MIP network to enable secure and efficient bootstrapping of the shared secret between the Mobile Node (MN) and Radius AAA Server, MN-AAA key (and other cryptographic keys). The DMU procedure utilizes RSA Public key cryptography to securely distribute unique MIP keys to potentially millions of cdma2000(R) 1X and HRPD/1xEV-DO Mobile Nodes (MN) using the same RSA Public key. By leveraging the existing cdma2000(R) 1X authentication process, the Dynamic Mobile IP Key Update process employs a Shared Mutual Authentication mechanism in which device-to-network authentication is facilitated using cdma2000(R) 1X challenge-response authentication and network-to-device authentication is facilitated using RSA encryption. By utilizing RSA encryption, the MN (or MN manufacturer) is able to pre-generate MIP keys (and the CHAP key) and pre-encrypt the MIP keys prior to initiation of the DMU procedure. By employing this pre- computation capability, the DMU process is an order of magnitude more efficient than Diffie-Hellman Key Exchange. 2. Basic Dynamic MIP Key Update Mechanism The DMU procedure is basically an Authentication and Key Distribution (AKD) protocol which is more easily understood by separately describing the mechanism's two functional goals: 1) encrypted key distribution and 2) shared mutual authentication. 2.1 RSA Encrypted Key Distribution By utilizing RSA Public Key Cryptography, millions of MNs can be pre- loaded with a common RSA Public (encryption) key (by the MN manufacturer) while the associated RSA Private (decryption) key is securely distributed from the MN manufacturer to each service provider. Alternatively, a service provider can generate its own RSA Public/Private key pair and only distribute the RSA Public key to MN manufacturers for pre-loading of MNs. Carroll Expires - March 2004 [Page 3] Dynamic MIP Key Update September 2003 During the manufacturing process, the MN manufacturer pre-loads each MN with the RSA Public key. When the MN is powered-up (or client application initiated), the MN can pre-generate and encrypt MIP keys for distribution to the Home RADIUS AAA Server during the DMU process. Alternatively, the MN manufacturer can pre-generate MIP keys, encrypt the MIP key payload, and pre-load the MN with multiple encrypted MIP key payloads to enable the DMU procedure. During the initial registration process (or when the AAA requires MIP key update), the MN: 1) generates the appropriate MIP keys, CHAP key, and authentication information, 2) uses the embedded RSA Public key to encrypt the payload information, 3) and appends the payload to the MIP Registration Request. When the Radius AAA Server receives the encrypted payload (defined as MIP_Key_Data later), the AAA Server uses the RSA Private key to decrypt the payload and recover the MIP keys. MN BS/PDSN/FA AAA -- ---------- --- ------------------ ------------------- | RSA Public Key | | RSA Private Key | | Pre-loaded by | | Pre-loaded by | | Manufacturer | | Service Provider | ------------------ ------------------- Registration Request, (MIP keys), RSA Public Key |-------------------->| | Access Request, (MIP keys), | RSA Public Key |---------------------->| ------------------- | Decrypt MIP | | Keys using RSA | | Private Key | ------------------- Figure 1. RSA Encrypted Key Distribution 2.2 Shared Mutual Authentication Mutual authentication is achieved by delegation of the MN/device authentication by the AAA Server to cdma2000(R) 1X HLR/AC [5] while the MN utilizes RSA encryption to authenticate the AAA Server. MN/device authentication is based on the assumption that the MN's Mobile Station (MS) has an existing A-key and SSD with the cdma2000(R) 1X network. When MS call origination occurs, the AC Carroll Expires - March 2004 [Page 4] Dynamic MIP Key Update September 2003 authenticates the MS. If authentication is successful, the BS passes the MSID (e.g. MIN) to the PDSN. The "Authenticated MSID" is then included in the Radius Access Request (ARQ) message sent from the PDSN to the AAA server. Because the Radius AAA stores the MSID associated with an MN subscription, the AAA server is able to "Authorize" MN access if the "Authenticated MSID" matches the RADIUS AAA MSID, i.e. the RADIUS AAA is delegating its authentication function to the cdma2000(R) 1X HLR/AC. RADIUS AAA Server authentication (by the MN) is enabled by including a random number (AAA_Authenticator) in the encrypted payload sent from the MN to the AAA Server. Only the possessor of the proper RSA Private key will have the ability to decrypt the payload and recover the unique AAA_Authenticator. If the MN receives the correct AAA_Authenticator (returned by the AAA Server), the MN is assured that it is not interacting with a false Base Station (BS). Because cdma2000(R) A-key/SSD authentication is not available in 1xEV-DO or a particular cdma2000(R) 1X network may not support A-key authentication, the DMU procedure also includes a random number (MN_Authenticator) generated by the MN (and/or pre-loaded by the manufacturer), which enables the Radius AAA to optionally authenticate the MN (in 1XEV DO network only). Carroll Expires - March 2004 [Page 5] Dynamic MIP Key Update September 2003 MN BS/PDSN/FA HLR/AC AAA -- ---------- ------ --- ------------------ ------------------- | RSA Public Key | | RSA Private Key | | Pre-loaded by | | Pre-loaded by | | Manufacturer | | Service Provider | ------------------ ------------------- | Global Challenge |<-------------| | | Auth_Response |------------->| | Auth_Response |---------------->| ------------------ | IS-2000 | | Authentication | ------------------ Auth_Success | |<----------------| ------------------ | BS forwards | | Authenticated | | MSID to PDSN | ------------------ Registration Request (MIP keys, AAA_Authenticator), | RSA Public Key |------------->| | Access Request, MSID, | (MIP keys, AAA_Authenticator), | RSA Public Key |------------------------------->| ------------------- | Check MSID, | | Decrypt AAA_- | | Authenticator | ------------------- Access Reject, AAA_Authenticator | |<-------------------------------| Registration Reply, AAA_Authenticator |<-------------| ------------------ | Check AAA_- | | Authenticator | ------------------ Figure 2. Shared Mutual Authentication Carroll Expires - March 2004 [Page 6] Dynamic MIP Key Update September 2003 2.3 Encrypted Password / Encrypted One-Time Password Authentication The DMU procedure alternatively utilizes a password, the MN_Authenticator, to support MN authentication in cdma2000(R) HRPD/1xEV-DO or whenever 1X RAN authentication (e.g. CAVE) is not available. Furthermore, the MN_Authenticator is transmitted from the MN to the Home AAA Server within the RSA-encrypted MIP_Key_Data payload to prevent interception and possible re-use by an attacker. Ideally, the MN_Authenticator is utilized as a One-Time Password, however, RSA encryption allows the MN_Authenticator to possibly be re-used based on each Service Provider's key distribution policy. When the encrypted MIP keys are decrypted at the Home AAA Server, the MN_Authenticator is also decrypted and compared with a copy of the MN_Authenticator stored within the AAA Server. The Home AAA Server receives a copy of the MN_Authenticator out-of-band (not using the 3GPP2 network) utilizing one of numerous possible methods outside the scope of the standard. For example, the MN_Authenticator MAY be: 1) read out by a Point-of-Sale provisioner from the MN, input into the subscriber profile, and delivered along with the NAI, via the billing/provision system to the Home AAA server, or 2) verbally communicated to a customer care representative via a call, or 3) input by the user interfacing with an IVR. The out-of-band MN_Authenticator delivery is purposely precluded from the standard to maximize the Service Provider's implementation flexibility. It is possible for an unscrupulous provisioner or distribution employee to extract the MN_Authenticator prior to the DMU procedure, however the risk associated with such a disclosure is minimal. Because the HRPD/1xEV-DO MN does not transmit a device identifier during the initial registration process, an attacker, even with a stolen MN_Authenticator, cannot correlate the password with a particular MN device or NAI, which is typically provisioned just prior to DMU procedure initiation. The MN_Authenticator is typically generated by a random/pseudorandom number generator within the MN. MN_Authenticator generation is initiated by the MN user, however it MAY be initially pre-loaded by the manufacturer. When the MN_Authenticator is reset (i.e. a new MN_Authenticator is generated), all MIP_Data_Key payloads using the previous MN_Authenticator are discarded and the MN immediately re- encrypts a MIP_Key_Data payload containing the new MN_Authenticator. The MN_Authenticator MUST NOT change unless it is explicitly reset by the MN user. Thus, the MN will generate new MIP_Key_Data payloads using the same MN_Authenticator until the MN_Authenticator is updated. Carroll Expires - March 2004 [Page 7] Dynamic MIP Key Update September 2003 ------------------------- | User-initiated | | MN_Authenticator[x] | | Generation | ------------------------- | v ----------------------------- ------------------------------ | Manufacturer | | Delete MN_Authenticator[y], | | MN_Authenticator[y] |----->| Store MN_Authenticator[x] | | Generation** | | in MN | ----------------------------- ------------------------------ | v ------------------------- | Delete MIP_Key_Data | | Payload using | | MN_Authenticator[y] | ------------------------- | v ----------------------------- ------------------------- | KEYS_VALID and committed; | | Generate MIP_Key_Data | | delete MIP_Key_Data |----->| Payload using | | Payload | | MN_Authenticator[x] | ----------------------------- ------------------------- ^ | | v ----------------------------- ------------------------- | DMU MIP_Key_Data | | Store MIP_Key_Data | | Delivery |<-----| Payload | ----------------------------- ------------------------- Figure 3. MN_Authenticator and MIP_Key_Data Payload State Machine **Note: Manufacturer pre-load of MN_Authenticator is not essential since the MN_Authenticator is typically generated by the MN. However, manufacturer pre-load may reduce provisioner burden of accessing a device such as a modem to recover the MN_Authenticator for entry into the Serivce Provider provisioning system. 3. Dynamic MIP Key Update Advantages over OTASP The DMU procedure has numerous advantages over the current Over-the- Air Service Provisioning (OTASP) [6] procedure including: * MIP key distribution occurs directly between the MN and AAA Server at the IP Layer. Eliminates the need for an interface between the OTAF and AAA server. Carroll Expires - March 2004 [Page 8] Dynamic MIP Key Update September 2003 * Supports MIP key distribution for cdma2000(R) 1X and HRPD/1xEV- DO MN. OTASP only supports cdma2000(R) 1X MIP key distribution. * Facilitates MIP key distribution to MN using Relay-mode MS. OTASP only delivers MIP keys to MS. For example, OTASP cannot delivery MIP keys to Laptop MN interfacing with MS modem. * Pre-encryption of MIP_Key_Data allows DMU procedure to be order of magnitude faster than Diffie-Hellman Key Exchange. * MN manufacturer can pre-generate MIP keys, pre-encrypt the MIP key payload, and pre-load the payload in an MN. Thus, an MN with limited processing power is never required to use RSA encryption. An OTASP device is always forced to perform computationally expensive exponentiations during the key update process. * MN is protected against False BS Denial-of-Service (DOS) attack in which False BS changes the MIP key for MNs in its vicinity. OTASP Diffie-Hellman Key Exchange vulnerable to BS DOS. * Utilizes mutual authentication. OTASP Diffie-Hellman Key Exchange does not utilize authentication. * From a procedural perspective, only TSG-P/TR-45.6 standards subcommittees are affected by DMU Procedure. 4. Detailed DMU Procedure Description and Requirements The Dynamic Mobile IP Update procedure is a secure, yet extremely efficient mechanism for distributing essential MIP cryptographic keys (e.g. MN-AAAh key and MN-HA key) and the Simple IP CHAP key. The DMU protocol enables pre-computation of the encrypted key material payload, known as MIP_Key_Data. The DMU procedure purposely avoids the use of Pubic Key Infrastructure (PKI) Certificates in order to greatly enhance the procedure's efficiency using MIP_Key_Data pre- encryption within the MN. 4.1 RSA Public Key Cryptography RSA Public Key encryption and decryption MUST be performed in accordance with RFC 2313 [7] PKCS #1: RSA Encryption Version 1.5. DMU MUST support RSA with a 1024-bit modulus by default. DMU MAY also support 768-bit or 2048-bit RSA depending on the MN user's efficiency or security requirements. RSA computation speed-ups using low exponent RSA or the value "65537" are acceptable. Carroll Expires - March 2004 [Page 9] Dynamic MIP Key Update September 2003 4.2 Other Public Key Algorithms DMU does not preclude the use of other Public key technologies. The protocol includes a Public Key Type field that defines the type of encryption used. 4.3 Why no Public Key Infrastructure (PKI)? DMU is designed to maximize the efficiency of Mobile IP (MIP) key distribution for cdma2000(R) MNs. The use of a Public key Certificate would improve the flexibility of the MIP key update process by allowing a Certificate Authority (CA) to vouch for the RSA Public Key delivered to the MN. Unfortunately, the use of a Public Key Certificate would significantly reduce the efficiency (speed and overhead) of the MIP key update process. For instance, each MN must be pre-loaded with the CA's Public Key. During the MIP key distribution process, the network must first deliver its RSA Public Key (in a Certificate) to the MN. The MN must then use RSA to decrypt the Certificate's digital signature to verify that the presented RSA public key is legitimate. Such a process significantly increases the number of exchanges, increases air interface overhead, increases the amount of MN computation, and slows the MIP key update process. Aside from the operational efficiency issues, there are numerous policy and procedural issues that have previously hampered the deployment of PKI in commercial networks. On a more theoretical basis, PKI is likely unnecessary for this key distribution model. PKI is ideal for a Many-to-Many communications model such as within the Internet where many different users interface with many different Websites. However, in the cellular/PCS Packet Data environment, a Many-to-One (or few) distribution model exists in which many users interface with one wireless Carrier to establish their Mobile IP security associations (i.e cryptographic keys). 4.4 Cryptographic Key Generation The DMU procedure relies on each MN to randomly/pseudo-randomly generate the MN_AAAh key, MN_HA key, and Simple IP CHAP key. Each MN MUST have the capability to generate random/pseudo-random numbers in accordance with the guidelines specified in RFC 1750 Randomness Recommendations for Security. Although it may be more secure for the network to generate cryptographic keys at the AAA server, client cryptographic key generation is acceptable due to the significant efficiency Carroll Expires - March 2004 [Page 10] Dynamic MIP Key Update September 2003 improvement in the update process via pre-generation and pre- encryption of the MIP keys. 4.5 MIP_Key_Data Payload MIP cryptographic keys (MN_AAAh key and MN_HA key) and the Simple IP CHAP key are encapsulated and encrypted into a MIP_Key_Data Payload (along with the AAA_Authenticator and MN_Authenticator). The MIP_Key_Data Payload is appended to the MN's MIP Registration Request (RRQ) as a MIP Vendor/Organization-Specific Extension (See IETF RFC 3115 [8] Mobile IP Vendor/Organization-Specific Extensions). When the PDSN converts the MIP RRQ to a Radius Access Request (ARQ) message, the MIP_Key_Data Payload is converted from a MIP Vendor/Organization-Specific Extension to a 3GPP2 Vendor Specific Radius Attribute. Upon receipt of the Radius Access Request, the Radius AAA decrypts the MIP_Key_Data payload using the RSA Private (decryption) key associated with the RSA Public (encryption) used to encrypt the MIP_Key_Data payload. The MIP_Key_Data is defined as follows: MIP_Key_Data = RSA Pub_Keyi [MN_AAAh key, MN_HA key, CHAP_key, MN_Authenticator, AAA_Authenticator], Public_Key_IDi, DMUV Where: MN_AAA key = 128-bit random MN / AAA Server key (encrypted) MN_HA key = 128-bit random MN / Home Agent (HA) key (encrypted) CHAP_key = 128-bit random Simple IP authentication key (encrypted) Note: the Simple IP CHAP key as not the same as the AT-CHAP key used for A12 Interface authentication [9]. MN_Authenticator = 24-bit random number (displayed as 8 decimal digit number. To be used for 1xEV DO network.) (encrypted) AAA_Authenticator = 64-bit random number used by MN to authenticate AAA Server. (encrypted) DMU Version (DMUV) = 4 bit identifier of DMU version. Public Key Identifier (Pub _Key_ID) = PKOID, PKOI, PK_Expansion, ATV Where: Public Key Organization Identifier (PKOID) = 8-bit serial number identifier of Public Key Organization (PKO) that created the Public Key. Carroll Expires - March 2004 [Page 11] Dynamic MIP Key Update September 2003 Public Key Organization Index (PKOI) = 8-bit serial number used at PKO discretion to distinguish different Public/Private key pairs. PK_Expansion = 8-bit field to enable possible expansion of PKOID or PKOI fields. (Note: Default value = 0xFF) Algorithm Type and Version (ATV) = 4-bit identifier of the algorithm used. Note: If 1024-bit RSA is used, the encrypted portion of the payload is 1024 bits (128 bytes) long. With the 28 bit Public Key Identifier and 4 bit DMUV, the total MIP_Key_Data payload is 132 bytes long. 4.6 RSA Key Management The wireless Service Provider or carrier MUST generate the RSA Public/Private key pair(s). An organization within the Service Provider MUST be designated by the Service Provider to generate, manage, protect, and distribute RSA Private keys (to the AAA Server) and Public keys (to the MN manufacturers) in support of the DMU procedure. Each RSA Public/Private key pair, generated by the wireless carrier, MUST be assigned a unique Public Key Identifier in accordance with Section IX. RSA Private keys MUST be protected from disclosure to unauthorized parties. The Service Provider organization with the responsibility of generating the RSA Public/Private key pairs MUST establish a RSA key management policy to protect the RSA Private (decryption) keys. RSA Public keys MAY be freely distributed to all MN manufacturers (along with the Public Key Identifier). Because one RSA Public key can be distributed to million of MNs, it is acceptable to distribute the RSA Public key (and Public Key Identifier) to MN manufacturers via e-mail, floppy disk, or VZW Website. The preferred method is to simply publish the RSA Public key and associated Public Key Identifier in the DMU Requirements document sent to each MN manufacturer/OEM. RSA Private keys MAY be loaded into the RADIUS AAA server manually. Access to the RADIUS AAA Server RSA Private keys SHOULD be restricted to authorized personnel only. The wireless Service Provider MAY accept RSA Private key(s) (and Public Key Identifier) from MN manufacturers or other Service Providers that have preloaded MNs with manufacturer-generated RSA Carroll Expires - March 2004 [Page 12] Dynamic MIP Key Update September 2003 Public keys. One Service Provider MAY negotiate an agreement with another Service Provider in which both Service Providers share and protect each other's RSA Private keys. 4.7 RADIUS AAA Server RADIUS or DIAMETER AAA Server MUST support the DMU Procedure. The AAA Server MUST support RSA Public key cryptography and maintain a database of RSA Private (decryption) keys indexed by the Public Key Identifier. Delivery of the RSA Private key(s) to AAA Server from the MN manufacturer(s) is outside the scope of this documents. However, RSA Private key(s) delivery via encrypted e-mail or physical (mail) delivery is likely acceptable. RADIUS AAA Server access MUST be limited to authorized personnel only. RADIUS AAA Server MUST support 1024-bit RSA decryption. RADIUS AAA Server MUST maintain a database of RSA Public/Private key pair indexed by the Public Key Identifier. RADIUS AAA Server MUST support the RADIUS attributes specified in Section 8. RADIUS AAA Server MUST support a subscriber specific MIP Update State Field. When the MIP Update State Field set to UPDATE KEYS (1), the AAA Server MUST initiate the DMU procedure by including the MIP_Key_Request attribute in an Access Reject message sent to the PDSN. The MIP Update State Field MAY be set to UPDATE KEYS (1) by Service ProviderĘs Billing/Provisioning system based on IT policy. Upon verification of MN-AAA Authentication Extension using decrypted MN_AAA key, the AAA Server MUST set the MIP Update State Field to KEYS UPDATED (2). Upon verification of the MN-Authentication Extension on a subsequent RRQ/ARQ, the AAA Server MUST set the MIP Update State Field to KEYS VALID (0). The AAA Server MUST maintain a MIP Update State Field, for each subscription, in one of three states (0 = KEYS VALID, 1 = UPDATE KEYS, 2 = KEYS UPDATED). RADIUS AAA Server MUST decrypt the encrypted portion of the MIP_Key_Data payload using the appropriate RSA Private (decryption) key. RADIUS AAA Server MUST check the MN_AAA Authentication Extension of the DMU RRQ using the decrypted MN_AAA key. Carroll Expires - March 2004 [Page 13] Dynamic MIP Key Update September 2003 RADIUS AAA Server MUST include the AAA_Authenticator in the Access Accept as a 3GPP2 Radius Attribute. RADIUS AAA Server MUST support the MN_Authenticator options specified in Section X, 1. AAA Server MUST comply with DMU Procedure failure operation specified in Section V. RADIUS AAA Server MUST support manual hexadecimal entry of MN_AAA key, MN_HA key and Simple IP CHAP key via the AAA GUI for each subscription. RADIUS AAA Server MUST provide a mechanism to validate the MIN/IMSI. When the MIN/IMSI validation is on, the RADIUS AAA Server MUST compare the MIN/IMSI sent from the PDSN with the MIN/IMSI in the AAA subscription record/profile. If the MINs or IMSIs do not match, the AAA Server MUST send an Access Reject to the PDSN/FA. The Access Reject MUST NOT contain a MIP Key Data request When the "Ignore MN_Authenticator" bit is not set, the AAA Server MUST check whether MN_AuthenticatorMN = MN_AuthenticatorAAA. If the MN_Authenticators do not match, the AAA Server MUST send an Access Reject to the PDSN/FA. The Access Reject MUST NOT contain a MIP Key Data request. AAA Server MUST include its PKOID (or another designated PKOID) in the MIP_Key_Request Radius Attribute. AAA Server MUST compare the PKOID sent in the MIP_Key _Data Radius Attribute with a list of valid PKOIDs in the AAA Server. If the PKOID is not valid, the AAA Server MUST send an Access Reject to the PDSN with the Verizon Wireless Vendor Specific "Invalid Public Key" Radius attribute. Note: the same Radius attribute may be assigned a different Vendor identifier. AAA Server MUST support delivery of the MN-HA key from the AAA server using 3GPP2 Radius Vendor-Specific Attributes as specified in TIA/EIA/IS-835B Section 6.3.2 using the MN-HA Shared Key (Vendor-Type = 58) and MN-HA SPI (Vendor-Type = 57). AAA Server MUST always accept the A12 Access Request for a particular subscriber when the UPDATE KEYS (1) and KEYS UPDATED (2) states are set. In the KEYS VALID (0) state, the AAA Server MUST check to Access Request normally. Carroll Expires - March 2004 [Page 14] Dynamic MIP Key Update September 2003 AAA Server MUST reject an Access Request with the MIP_Key_Data Radius Attribute while the AAA Server is in the KEYS VALID state, i.e., the AAA MUST NOT allow an unsolicited key update to occur. 4.8 MN (Handset or Modem) MN manufacturer MUST pre-load the Wireless Carrier RSA Public key (and Public Key Identifier). MN manufacturer MUST pre-generate and pre-load the MN_Authenticator. MN MUST support 1024-bit RSA Encryption using the pre-loaded RSA Public key. MN MUST support MN_AAA, MN_HA, and CHAP random/pseudo-random key generation (in accordance with RFC 1750). MN MUST support random/pseudo-random AAA_Authenticator and MN_Authenticator generation (in accordance with RFC 1750). Upon power-up of an MN handset or launch of the MN client, the MN MUST check whether a MIP_Key_Data payload has been computed. If no MIP_Key_Data payload exists, the MN MUST generate and store a MIP_Key_Data payload. The MN MUST maintain at least one pre- generated MIP_Key_Data payload. MN MUST construct the MIP_Key_Data payload in accordance with Section 4.5. MN MUST initiate the DMU Procedure upon receipt of MIP Registration Reply with the MIP_Key_Request Verizon Wireless Vendor/Organization- specific Extension. Upon receipt of an RR including the MIP_Key_Request, the MN MUST check the PKOID sent in the MIP_Key_Request. If the MN has a Public key associated with the PKOID, the MN MUST encrypt the MIP_Key_Data payload using that Public key. MN MUST have the capability to designate one Public key as the Default Public key if the MN supports multiple Public keys. MN MUST insert the Verizon Wireless Vendor/Organization-specific MIP_Key_Data Extension (or another Organization-specific MIP_Key_Data Extension) after the Mobile-Home Authentication Extension, but before the MN-AAA Authentication Extension. The MIP_Key_Data Extension must also be located after the FA Challenge Extension if present. Upon initiation of the DMU Procedure, the MN MUST compute MIP authentication extensions using the newly-generated temporary MN_AAA Carroll Expires - March 2004 [Page 15] Dynamic MIP Key Update September 2003 and MN_HA keys. Upon receipt of the AAA_Authenticator MIP Extension, the MN MUST compare the AAA_AuthenticatorMN (sent in the encrypted MIP_Key_Data payload) with the AAA_AuthenticatorAAA(returned by the AAA Server). If both values are the same, the MN MUST designate the temporary MN_AAA, MN_HA key, and Simple IP CHAP key as permanent. The MN MUST set its MIP Update State field to KEYS VALID. MN MUST support reset (re-generation) of the MN_Authenticator by the MN user as specified in Section 6.2. MN MUST enable the MN user to view the MN_Authenticator. MN_Authenticator (24-bit random number) MUST be displayed as an 8 decimal digit number as specified in Section 6.2. The MN manufacturer MUST pre-load each MN with a unique random 24-bit MN_Authenticator. Upon reset of the MN_Authenticator, the MN MUST delete all MIP_Key_Data payloads based on the old MN_Authenticator and generate all subsequent MIP_Key_Data payloads using the new MN_Authenticator. (until the MN_Authenticator is explicitly re-set again by the MN user). MN MUST support manual entry of all cryptographic keys such as the MN_AAA, MN_HA, and Simple IP CHAP key. MN MUST support hexadecimal digit entry of a 128-bit key. (Note: certain Simple IP devices only enable ASCII entry of a password as the CHAP key. It is acceptable for future devices to provide both capabilities, i.e. ASCII for a password or hexadecimal for a key. The authors recommend the use of strong cryptographic keys.) MN MUST support the Verizon Wireless MIP Vendor/Organization-Specific Extensions specified in Section IX. MN MUST update the RRQ Identification field when re-transmitting the same MIP_Key_Data in a new RRQ. MN MUST comply with DMU Procedure failure operation specified in Section V. The RSA Public Key MAY be stored in the MN flash memory as a constant while being updatable via software patch. 4.9 PDSN / Foreign Agent (FA) PDSN MUST support Verizon Wireless Radius Vendor Specific Attributes specified in Section VIII and Verizon Wireless MIP Vendor/Organization-Specific Extensions specified in Section IX. Carroll Expires - March 2004 [Page 16] Dynamic MIP Key Update September 2003 PDSN MAY support Radius Vendor Specific Attributes specified in Section VIII and MIP Vendor/Organization-Specific Extensions specified in Section IX using another Organization identifier (e.g., 3GPP2 Organization ID). Upon receipt of an Access Reject containing the MIP_Key_Update_Request attribute, PDSN MUST send a RR to the MN with the MIP_Key_Request Vendor/Organization-Specific Extension. The PDSN MUST use the RR error code = 89 (Vendor Specific) and MUST not tear down the PPP session after transmission. Upon receipt of an Access Reject containing the AAA_Authenticator attribute, the PDSN MUST send a RR with AAA_Authenticator MIP Vendor/Organization-Specific Extension. The PDSN MUST use the RR error code = 89 (Vendor Specific) and MUST NOT tear down the PPP session after transmission. Upon receipt of an Access Reject containing the Public Key Invalid attribute, the PDSN MUST send a RR with Public Key Invalid MIP Vendor/Organization-Specific Extension. The PDSN MUST use the RR error code = 89 (Vendor Specific) and MUST NOT tear down the PPP session after transmission. Upon receipt of a RRQ with the MIP_Key_Data Vendor/Organization- Specific Extension, the PDSN MUST convert the RRQ to an ARQ with MIP_Key_Data attribute. The PDSN MUST send the ARQ to the AAA server. PDSN/FA MUST comply with DMU Procedure failure operation specified in Section V. PDSN/FA MUST include the PKOID from the Access Reject MIP_Key_Update_Request attribute in the MIP_Key_Request MIP extension sent to the MN. 4.10 Home Agent (HA) HA MUST support Verizon Wireless MIP Vendor/Organization-Specific Extensions specified in Section IX. (Note: HA may not encounter a DMU MIP extension.) HA MUST support MIP Vendor/Organization-Specific Extensions specified in Section IX using another Organization identifier (e.g., 3GPP2 Organization ID). (Note: HA may not encounter a DMU MIP extension.) HA MUST support delivery of the MN-HA key from the Home AAA server using 3GPP2 Radius Vendor-Specific Attributes as specified in TIA/EIA/IS-835B Section 6.3.2 using the MN-HA Shared Key (Vendor-Type = 58) and MN-HA SPI (Vendor-Type = 57). Carroll Expires - March 2004 [Page 17] Dynamic MIP Key Update September 2003 4.11 DMU Procedure Network Flow This section provides a flow diagram and detailed description of the process flow involving the Dynamic Mobile IP Update procedure process within the IS-2000 network. MN BS PDSN/FA AAAh -- -- ------- ---- --------------------- ------------------- | 1: RSA Public Key | | RSA Private Key | | Pre-loaded by | | Pre-loaded by | | Manufacturer | | Service Provider | --------------------- ------------------- --------------------------------------------------------- | 2: MS/BS: IS-2000 Call Origination and Authentication | | 3: MN/PDSN/FA: PPP Session Establishment | --------------------------------------------------------- | 4: Registration Request (RRQ) |--------------------------------->| 5: Access Request w/MSID |------------>| -------------------- | 6: MIP Update State| | is "Update Keys" | -------------------- 7: Access Reject with | MIP_Key_Update_Request | Radius Attribute | |<------------| 8: Registration Reply (RR) | with MIP_Key_Request MIP | Vendor/organization-specific | attribute | |<---------------------------------| ------------------- | 9: MN generates | | MIP_Key_Data | | using temporary | | MIP keys | ------------------- | 10: RRQ with MIP_Key_Data | Vendor/organization-specific attribute |--------------------------------->| 11: Access Request | w/MSID | and MIP_Key_Data | Radius attribute |------------>| Figure 4. DMU Procedure Flow (part 1) Carroll Expires - March 2004 [Page 18] Dynamic MIP Key Update September 2003 MN BS/PDSN PDSN/FA AAAh -- ------- ------- ---- | ------------------- | 12: decrypt | | MIP_Key_Data, | | verify MN-AAA | | authentication | | extension, set | | MIP Update State | | = "Keys Updated" | ------------------- 13: Access Reject with | AAA_Authenticator | Radius Attribute | |<------------| 14: Registration Reply (RR) | with AAA_Authenticator MIP | Vendor/organization-specific | attribute | |<---------------------------------| ---------------------- | 15: verify | | AAA_Authenticator, | | store temporary | | MIP keys as | | permanent keys | ---------------------- | 16: RRQ |--------------------------------->| Access Request | w/MSID |------------>| -------------------- | 17: verify MN-AAA | | authentication | | extension, set | | MIP Update State | | = "Keys Valid" | -------------------- Access Accept | |<------------| Figure 4. DMU Procedure Flow (part 2) Carroll Expires - March 2004 [Page 19] Dynamic MIP Key Update September 2003 MN PDSN/FA AAAh HA -- ------- ---- -- | 18. Registration Request (RRQ) |-------------------------------->| 19: Access Request | |<-----------------| Access Accept | with MN-HA key | |----------------->| ------------------- | verify | | mobile-home | | authentication | | extension | ------------------- 20. Registration Reply (RR) | |<--------------------------------| RR | |<--------------| Figure 4. DMU Procedure Flow (part 3) Each step in the Figure 4 DMU Process is described as follows: 1. Each RSA Public/Private Key pair must be generated in accordance with RFC 2313. Each Public/Private key pair MUST be assigned a unique Public Key Identifier (PKOID) by its creator. If the Service Provider does not generate the Public/Private Key pair and deliver the RSA Public Key to the MN manufacturer for pre-installation in the MN, the MN manufacturer MUST generate the RSA Public/Private Key pair (using a 1024-bit modulus) and pre-load all MNs with the RSA Public (encryption) key. The MN manufacturer MUST distribute the RSA Private (decryption) key, in a secure manner, to the appropriate service provider(s). It is acceptable for the MN manufacturer to distribute the same Private (decryption) key to multiple service providers. 2. Assuming that the cdma2000(R) 1X MN has been provisioned with an A-key and SSD, the cdma2000(R) 1X MS initiates a call origination and authenticates itself to the IS-2000 network. Upon cdma2000(R) 1X (CAVE) authentication success, the BS sends the "authenticated" MSID (e.g. MIN) to the PDSN. 3. The MN and PDSN establish a PPP session. 4. The MN sends a MIP Registration Request (RRQ) to the PDSN. Carroll Expires - March 2004 [Page 20] Dynamic MIP Key Update September 2003 5. The PDSN converts the MIP RRQ into a Radius Access Request (ARQ) message, includes the MSID in the ARQ, and forwards the ARQ to the Home AAA server. 6. The AAA Server compares the authenticated MSID (sent from the PDSN) with the MSID in its subscriber database (associated with the NAI). If the AAA MIP Update State Field is set to UPDATE KEYS (1), the AAA Server rejects Packet Data access and orders a MIP key update. 7. The AAA Server sends an Access Reject (code = 3) message to the PDSN with MIP_Key_Update_Request 3GPP2-Specific Radius Attribute. 8. The PDSN converts the Access Reject to a MIP Registration Reply (RR) with a MIP_Key_Request MIP Vendor/Organization-Specific Extension and sends the RR to the MN. RR Code = 89 (Vendor Specific). 9. The MN sets the MN MIP Update State = UPDATE KEYS. If the MN has no pre-generated and pre-encrypted the MIP_Key_Data payload, the MN MUST generate the MN_AAA key, MN_HA key, Chap key, MN_Authenticator, and AAA_Authenticator in accordance with RFC 1750. Except for the Public Key Identifier, all generated values MUST be encrypted using the pre-loaded RSA Public (encryption) key. The newly generated MN_AAATEMP Key and MN_HATEMP MUST be used to calculate the MN-AAA and Mobile-Home Authentication Extensions for the current RRQ. Note: the MN MAY pre-compute the MIP_Key_Data payload by checking whether a payload exists during each MN power-up or application initiation. 10. The MN sends the RRQ with MIP_Key_Data MIP Vendor/Organization-Specific Extension (see RFC 3115) to the PDSN. 11. The PDSN converts the RRQ to a Radius ARQ with MIP_Key_Data Radius Attribute and forwards the ARQ to the home AAA Server. The MSID is included in the ARQ. 12. The AAA Server compares the authenticated MSID (sent from the PDSN) with the MSID in its subscriber database (associated with the NAI). If MSIDPDSN = MSIDAAA, the AAA server, using the Public Key Identifier, determines the appropriate RSA Private key and decrypts the encrypted portion of the MIP_Key_Data payload. The AAA Server verifies the MN-AAA Authentication Extension Authenticator using the decrypted MN_AAA key. If successful, the AAA Server updates the subscriber profile with Carroll Expires - March 2004 [Page 21] Dynamic MIP Key Update September 2003 the decrypted MN_AAA key, MN_HA key, and CHAP key. The AAA Server sets the AAA MIP Update State Field to KEYS UPDATED (2). 13. The AAA Server sends an Access Reject with AAA_Authenticator Radius Attribute to the PDSN. 14. The PDSN converts the Access Reject to a MIP RR with AAA_Authenticator MIP Vendor/Organization-Specific Extension. RR Code = 89 (Vendor Specific). 15. If AAA_AuthenticatorMN = AAA_AuthenticatorAAA, the MN assigns MN_AAATEMP to MN_AAA key and MN_HATEMP to MN_HA key (MN MIP Update State = KEYS VALID). Otherwise, the MN discards the temporary keys. 16. The MN initiates a new RRQ which is converted to an ARQ by the PDSN and forwarded to the AAA Server. 17. The AAA Server verified the MN-AAA Authentication Extension and sets the AAA MIP Update State Field to KEYS VALID (0). The AAA Server sends an Access Accept to the PDSN/FA. 18. The PDSN/FA sends the RRQ to the Home Agent (HA). 19. The HA sends an Access Request to the AAA Server. The AAA Server sends an Access Accept to the HA with the MN_HA key. The HA verifies the Mobile-Home Authentication Extension using the MN_HA key. 20. The HA sends RR to the PDSN/FA which forwards RR to the MN. RR Code = 0 (Success). 5. DMU Procedure Failure Operation This section was contributed by and is reproduced with the permission of Qualcomm Incorporated. To improve the robustness of the DMU Procedure to account for interruptions due to UDP message loss, RRQ retransmission, or MN failure, the AAA Server MUST maintain a MIP Update State Field, for each subscription, in one of three states (0 = KEYS VALID, 1 = UPDATE KEYS, 2 = KEYS UPDATED). Carroll Expires - March 2004 [Page 22] Dynamic MIP Key Update September 2003 MN PDSN/FA AAAh HA -- ------- ---- -- ---------------- ---------------- | MN state = | | AAAh state = | | Keys Valid | | Update Keys | ---------------- ---------------- | (A) RRQ |-------------->| ARQ |------------->| AR(Key_Update) | (B) RRP (Key_Update) |<-------------| |<--------------| ---------------- | MN state = | | Update Keys | ---------------- | (C) RRQ (MIP_Key_Data) |-------------->| ARQ (MIP_Key_Data) |------------->| ---------------- | AAAh state = | | Keys Updated | ---------------- AR (AAA_Auth) | (D) RRP (AAA_Auth) |<-------------| |<--------------| ---------------- | MN state = | | Keys Valid | ---------------- | RRQ |-------------->| ARQ |------------->| ---------------- | AAAh state = | | Keys Valid | ---------------- AA | |<-------------| RRQ |----------------------------------->| ARQ | |<--------------------| | AA |-------------------->| RRP | RRP |<--------------------| |<-----------------------------| Figure 5. DMU Failure Call Flow with MN and AAA States Carroll Expires - March 2004 [Page 23] Dynamic MIP Key Update September 2003 Each step in the Figure 5 is described as follows: 1. If (A) is lost, the MN retransmits (A). The AAA server expects (A). If the AAA server is in the UPDATE KEYS state, the AAA Server sends AR with MIP_Key_Update_Request attribute and the PDSN/FA sends (B). 2. If (B) is lost, the MN retransmits (A). The AAA server expects (C). If it receives (A), the AAA Server sends AR with MIP_Key_Update_Request attribute and the PDSN/FA retransmits (B). 3. If (C) is lost, the mobile retransmits (C). The AAA server expects (C) and updates the MIP keys appropriately. The AAA server transitions to KEYS UPDATED and commits the MIP_Key_Data. The AAA Server sends the AR with AAA_Authenticator attribute and the PDSN/FA replies to the MN with (D). 4. If (D) is lost, the mobile retransmits (C) using the same key data sent previously. The AAA server expects (A) using the same keys. a. If the AAA server receives (C) with the same keys it received previously, it retransmits the AR with AAA_Authenticator attribute and the PDSN replies with (D), containing the AAA_Authenticator. b. If the AAA server receives (C) with different keys than it received previously, AAA Server sends AR with MIP_Key_Update_Request attribute, the PDSN/FA retransmits (B), and AAA server transitions to UPDATE KEYS. c. If the AAA server receives (A) which fails authentication using the keys sent in (C), the AAA Server sends AR with MIP_Key_Update_Request, the PDSN/FA retransmits (B), and AAA server transitions to UPDATE KEYS. 5. Once the PDSN/FA receives (A), forwards the ARQ to the AAA server, and the MN-AAA Authenticator is verified using the MN_AAA key, the AAA Server transitions to the KEYS VALID state and the DMU process is complete. The AAA DMU state machine is described in Figure 6. Carroll Expires - March 2004 [Page 24] Dynamic MIP Key Update September 2003 -------------- --------------------->| Keys Valid |--------------- | Auth success using -------------- Need Key | | MIP_Key_Data Update | | | | Auth failed (invalid keys) | | or RRQ with different MIP_Key_Data | | --------------------------------- | | | | | | | v v ---------------- --------------- | Keys Updated | | Update Keys | ---------------- --------------- | ^ ^ | | | | | ------- --------------------------------- RRQ with same Got MIP_Key_Data MIP_Key_Data Figure 6. AAA Server DMU State Machine 6. cdma2000(R) HRPD/1xEV-DO Support Because the DMU Procedure occurs at the IP Layer, the DMU Procedure supports MIP key distribution in either the cdma2000(R) 1X or HRPD/1xEV-DO network. Because the cdma2000(R) HRPD/1xEV-DO network does not provide Radio Access Network (RAN) authentication, the DMU Procedure is more susceptible to a false MN attack (than in an cdma2000(R) 1X network with CAVE RAN authentication). For this reason, the DMU Procedure has the capability to optionally support device-to-network authentication using the MN_Authenticator. The method of MN_Authenticator delivery to the RADIUS/DIAMETER AAA is outside the scope of the TR-45/3GPP2 Standard, allowing Service Providers the flexibility to determine the most efficient/least intrusive procedure to support MN authentication (during the DMU Procedure). 6.1 RADIUS/DIAMETER AAA Support The RADIUS/DIAMETER AAA MUST support three MN_Authenticator options: 1. Ignore MN_Authenticator Depending on other potential authentication/fraud prevention options (outside the scope of the DMU Procedure), the RADIUS/DIAMETER AAA Server MUST have the capability to ignore the MN_Authenticator. For example, when the AAA Server decrypts the Carroll Expires - March 2004 [Page 25] Dynamic MIP Key Update September 2003 MIP_Key_Data payload, the AAA Server silently discards the MN_Authenticator. 2. Pre-Update Validation Prior to updating a subscription profile with the delivered MIP keys, the AAA Server MUST compare the MN_AuthenticatorMN (delivered via the encrypted MIP_Key_Data payload) with the MN_AuthenticatorAAA (possibly delivered via the Service Provider customer care or billing/provisioning system). 3. Post-Update Validation After the DMU Procedure is complete, the AAA Server stores the delivered MN_AuthenticatorMN and waits for delivery of the MN_AuthenticatorAAA (via Customer Care, IVR, or some other unspecified process). Once the MN_Authenticator is delivered to the AAA Server, the AAA Server MUST compare the MN_AuthenticatorMN (delivered via the encrypted MIP_Key_Data payload) with the MN_AuthenticatorAAA. If the Authenticators match, the AAA Server authorizes access and final update of the MIP keys. 6.2 MN Support The Mobile Node (MN) MUST store the 24-bit MN_Authenticator. The MN MUST display the MN_Authenticator as an 8 decimal digit number (via LCD display on a handset or via a GUI for a modem). If the MN resides within a handset, the user MAY display the MN_Authenticator using the following keypad sequence: "FCN + * + * + M + I + P + RCL". Otherwise, the MN MUST display the MN_Authenticator via the device's GUI. The MN MUST have the capability to reset the MN_Authenticator. In other words, the MN MUST have the capability to randomly/pseudo- randomly generate a new 24-bit MN_Authenticator in according with RFC 1750 upon user command. The reset feature mitigates possible compromise of the MN_Authenticator during shipment/storage. If the MN resides within a handset, the user MAY reset the MN_Authenticator using the following keypad sequence: "FCN + * + * + M + I + P + C + C + RCL". Otherwise, the MN MUST reset the MN_Authenticator via the device's GUI. The MN manufacturer MAY pre-load the MN with the MN_Authenticator. For example, by pre-loading the MN_Authenticator and affixing a sticker with the MN_Authenticator (8 decimal digit representation) to the MN (e.g. modem), the point-of-sale representative does not have to retrieve the MN_Authenticator from the MN interface. Carroll Expires - March 2004 [Page 26] Dynamic MIP Key Update September 2003 [Optional] The MN MAY maintain a separate primary and secondary queue of MN_Authenticator/MIP_Key_Data Payload pairs. When the MN user resets the primary MN_Authenticator, the MN discards the primary MN_Authenticator (and any associated MIP_Key_Data Payload) and assigns the MN_Authenticator in the secondary queue as the primary MN_Authenticator (and assigns any associated MIP_Key_Data Payloads to the primary queue). This feature enables the user/provisioner to reset the MN_Authenticator and immediately initiate the DMU procedure without losing the MIP_Key_Data Payload pre-encryption advantage. Upon MN_Authenticator transfer from the secondary to primary queue, the MN MUST generate a new MN_Authenticator and associated MIP_Key_Data Payload for the secondary queue. The MN MUST check both the primary and secondary MN_Authenticator/MIP_Key_Data Payload queues upon power-up or application initiation. The MN MUST maintain at least one MN_Authenticator/MIP_Key_Data Payload pair in each queue. 6.3 Informative MN_Authenticator Support MN authentication using the MN_Authenticator gives the service provider the maximum flexibility in determining how to deliver the MN_Authenticator the AAA Server. The method of MN_Authenticator delivery is outside the scope of the TR-45 IS-835/3GPP2 P.S0001-A-1 Standard. However, to provide some context to how the MN_Authenticator may support MN authentication/fraud prevention in the HRPD/1xEV-DO environment, we describe the following possible provisioning scenario. When a subscriber initially acquires their HRPD/1xEV-DO device and service, the point-of-sale representative records the subscription information into the billing/provision system via a computer terminal at the point-of-sale. The billing/provisioning system delivers certain information to the RADIUS AAA Server (e.g. NAI, MSID, ESN) including the MN_Authenticator which the point-of-sale representative retrieves via the MN device's display. In the case of a modem, the manufacturer may have pre-loaded the MN_Authenticator and placed a copy of the MN_Authenticator on a sticker attached to the modem. The point-of-sale representative simply copies the 8 decimal digit value of the MN_Authenticator into the customer profile. Once the MN is loaded with the proper NAI and powered-up, the MN initiates the DMU Procedure with the AAA Server. The AAA Server compares the MN- delivered MN_Authenticator with the billing system delivered MN_Authenticator. If the authenticators match, the AAA Server updates the subscriber profile with the delivered MIP keys and authorizes service. If the Post-Update option is enabled within the AAA Server, the AAA Server tentatively updates the subscription Carroll Expires - March 2004 [Page 27] Dynamic MIP Key Update September 2003 profile until receiving the MN_Authenticator via the billing/provision system. As another option, the Service Provider MAY use an IVR system in which the HRPD/1xEV-DO subscriber calls a provisioning number and inputs the MN_Authenticator. The IVR system then delivers the MN_Authenticator to the AAA Server for final validation and Packet Data Access. 7. Security Considerations The DMU Procedure is designed to maximize the efficiency of MIP key distribution while providing adequate key distribution security. The following list provides a description of potential security vulnerabilities and their relative risk to the DMU Procedure: 7.1 Cryptographic Key Generation by the MN Because the MN is required to properly generate the MN_AAA, MN_HA, and CHAP key, the MN must perform cryptographic key generation in accordance with accepted random/pseudo-random number generation procedures. MN manufacturers MUST comply with RFC 1750 [10] guidelines and Service Providers SHOULD ensure that manufacturers implement acceptable key generation procedures. The use of predictable cryptographic keys could be devastating to MIP security. However, the risk of not using acceptable random/pseudo-random key generation is minimal as long as MN manufacturers adhere to RFC 1750 guidelines. Furthermore, if a key generation flaw is identified, the flaw appears readily correctable via a software patch, minimizing the impact. 7.2 Man-in-the-Middle Attack The DMU procedure is susceptible to a MIM attack, however such an attack appears relatively complex and expensive. When 3GPP2 AKA is deployed within cdma2000(R) 1X, the MIM Attack will be eliminated. The risk of an MIM Attack is minimal due to required expertise, attack expense, and impending cdma2000(R) 1X mutual authentication protection. If a particular cdma2000(R) 1X network does not support A-key authentication, the MN_Authenticator MAY optionally be used. 7.3 RSA Private Key Compromise Because one RSA Private key may be associated with millions of MNs (RSA Public Key), it is important to protect the RSA Private key from disclosure to unauthorized parties. Each MN manufacturer MUST establish adequate security procedures/policies regarding the dissemination of the RSA Private key. RSA Private keys SHOULD be distributed to legitimate cdma2000(R) service providers only. It is Carroll Expires - March 2004 [Page 28] Dynamic MIP Key Update September 2003 acceptable for a MN manufacturer to distribute the same RSA Private key to multiple service providers to enable MIP key update. However, each service provider MAY generate their own RSA Public/Private key pair and require the MN manufacturer to include their own RSA Public key in a specific software patch if compromise of the RSA Private key is a significant concern. 7.4 RSA Encryption Several vulnerabilities have been identified in certain implementations of RSA, however they do not appear applicable to the DMU Procedure. 7.5 False Base Station/PDSN The MN appears to be protected against a False BS denial-of-service (DOS) attack, since only the proper AAA server can recover the AAA_Authenticator. 7.6 cdma2000(R) 1X False MN The cdma2000(R) 1X network appears adequately protected against a false MN by IS-2000 challenge-response authentication. 7.7 HRPD/1xEV-DO False MN The 1xEV-DO AAA Server MAY optionally authenticate the MN using the MN_Authenticator to prevent a fraudulent MN activation. 8. Verizon Wireless - Specific RADIUS Attributes Three new RADIUS Attributes are required to support the DMU Procedure and are specified as follows: Type: 26 Length: >9 Verizon Wireless Enterprise/Vendor ID: 12951 MIP_Key_Update_Request: ---------------------- The Home Radius AAA Server indicates MIP key update is required. Vendor-Type = 1 Vendor-Length = 3 bytes Vendor-Value= PKOID of the AAA Server Carroll Expires - March 2004 [Page 29] Dynamic MIP Key Update September 2003 MIP_Key_Data: ------------ Payload containing encrypted MN_AAA key, MN_HA key, CHAP key, MN_Authenticator, and AAA_Authenticator. Payload also contains Public Key Identifier. Vendor-Type = 2 Vendor-Length = 134 bytes NOTE: Vendor-Length depends on the size of the RSA modulus. For example, when RSA-512 is used, Vendor-Length = 70 bytes. Vendor-Value= 128 byte RSA encryption payload (when 1024-bit RSA used) which contains encrypted MN_AAA key, MN_HA key, CHAP key, MN_Authenticator, and AAA_Authenticator. The four (4) byte Public Key Identifier is concatenated to the encrypted payload. AAA_Authenticator: ----------------- 64-bit AAA_Authenticator value decrypted by the Home Radius AAA Server. Vendor-Type = 3 Vendor-Length = 10 bytes Vendor-Value= decrypted AAA_Authenticator from Home AAA Server. Public Key Invalid: ------------------ Home Radius AAA Server indicates that Public key used by MN is not valid. Vendor-Type = 4 Vendor-Length = 2 bytes Vendor-Value= none. Note: An Organization may define Specific Radius Attributes using their own Organization identifier. 9. Verizon Wireless Mobile IP Vendor/Organization-Specific Extensions Three Verizon Wireless Mobile IP Vendor/Organization-Specific Extensions (RFC 3115), required to support the DMU Procedure, are specified as follows: Type: 38 (CVSE-TYPE-NUMBER) Carroll Expires - March 2004 [Page 30] Dynamic MIP Key Update September 2003 Verizon Wireless Vendor ID: 12951 (high-order octet is 0 and low order octets are the SMI Network Management Private Enterprise Code of the Vendor in the network byte order, as defined by IANA). 0 7 8 15 16 31 --------------------------------------------------- | Type | Reserved | Length | --------------------------------------------------- | Vendor/Org-ID | --------------------------------------------------- | Vendor-CVSE-Type | Vendor-CVSE-Value ... | --------------------------------------------------- Figure 7. Critical Vendor/Organization Specific Extension MIP_Key_Request: --------------- The Home Radius AAA Server indicates MIP key update is required. Length = 7 NOTE: The RFC 3115 Editor has stated that the Reserved field is not included in the length determination. Vendor-CVSE-Type = 1 Vendor-CVSE-Value= PKOID sent in the Radius MIP_Key_Update_Request attribute. MIP_Key_Data: ------------ Payload containing encrypted MN_AAA key, MN_HA key, CHAP key, MN_Authenticator, and AAA_Authenticator. Payload also contains Public Key Identifier. Length = 138 NOTE: Length depends on the size of the RSA modulus. For example, when RSA-512 is used, Length = 74 bytes. Vendor-CVSE-Type = 2 Vendor-CVSE-Value= 128 byte RSA encryption payload (when 1024-bit RSA used) which contains encrypted MN_AAA key, MN_HA key, CHAP key, MN_Authenticator, and AAA_Authenticator. The four (4) byte Public Key Identifier and DMUV is concatenated to the encrypted payload. AAA_Authenticator: ----------------- 64-bit AAA_Authenticator value decrypted by the Home Radius AAA Server. Carroll Expires - March 2004 [Page 31] Dynamic MIP Key Update September 2003 Length = 14 bytes Vendor-CVSE-Type = 3 Vendor-CVSE-Value= decrypted AAA_Authenticator from Home AAA Server. Public Key Invalid: ------------------ The Home Radius AAA Server indicates that Public key used by MN is not valid. Length = 6 bytes Vendor-CVSE-Type = 4 Vendor-CVSE-Value= none. Note: An Organization may define Specific Vendor/Organization Extensions using their own Organization identifier. 10. Public Key Identifier and DMU Version The Public Key Identifier (Pub_Key_ID) is used only during the Dynamic Mobile IP Update (DMU) procedure to allow the AAA Server to distinguish between different Public keys (which may be assigned by different manufacturers, service providers, or other organizations). The Public Key Identifier consists of the PKOID, PKOI, PK_Identifier, and ATV fields. The DMU Version field enables subsequent revisions of the DMU procedure. ---------------------------------------------- | PKOID | PKOI | PK_Expansion | ATV | DMUV | ---------------------------------------------- 0 7 8 15 16 23 24 27 28 31 Figure 8. Public Key Identifier and DMUV Each Public Key Organization (PKO) MUST be assigned a Public Key Organization Identifier (PKOID) to enable the AAA Server to distinguish between different Public keys created by different PKOs (see Table 1). If a Service Provider does not provide the MN manufacturer with a (RSA) Public key, the manufacturer MUST generate a unique RSA Public/Private key pair and pre-load each MN with the RSA Public key (1024-bit modulus by default). The manufacture MAY share the same RSA Private key with multiple Service Providers as long as reasonable security procedures are established and maintained (by the manufacturer) to prevent disclosure of the RSA Private (decryption) key to an unauthorized party. Carroll Expires - March 2004 [Page 32] Dynamic MIP Key Update September 2003 The Public Key Organization Index (PKOI) is an 8-bit field in which the index the value is defined at the discretion of the PKO. For example, a device manufacturer MAY incrementally assign a new PKOI for each Public/Private key pair when the pair created. The PK_Expansion field enables support for additional PKOs or expansion of the PKOI. The DMU Version field allows for DMU Procedure version identification (see Table 2). The Algorithm Type and Version (ATV) field allows for identification of the Public Key algorithm and version used (see Table 3). Carroll Expires - March 2004 [Page 33] Dynamic MIP Key Update September 2003 Table 1. Public Key Organization Identification Table PKOID Public Key PKOID Public Key (HEX) Organization (PKO) (HEX) Organization (PKO) ----- ------------------ ----- ------------------ 00 RESERVED 40 Sanyo Fisher Company 01 RESERVED 41 Sharp Laboratories of America 02 RESERVED 42 Sierra Wireless, Inc. 03 RESERVED 43 Sony Electronics 04 RESERVED 44 Synertek, Inc. 05 RESERVED 45 Tantivy Communications, Inc. 06 RESERVED 46 Tellus Technology, Inc. 07 RESERVED 47 Wherify Wireless, Inc. 08 RESERVED 48 Airbiquity 09 RESERVED 49 ArrayComm 0A Verizon Wireless 4A Celletra Ltd. 0B AAPT Ltd. 4B CIBERNET Corporation 0C ALLTEL Communications 4C CommWorks Corporation, a 3Com Company 0D Angola Telecom 4D Compaq Computer Corporation 0E Bell Mobility 4E ETRI 0F BellSouth International 4F Glenayre Electronics Inc. 10 China Unicom 50 GTRAN, Inc. 11 KDDI Corporation 51 Logica 12 Himachal Futuristic 52 LSI Logic Communications Ltd. 13 Hutchison Telecom (HK), 53 Metapath Software Ltd. International, Inc. 14 IUSACELL 54 Metawave Communications 15 Komunikasi Selular 55 Openwave Systems Inc. Indonesia (Komselindo) 16 Korea Telecom Freetel, 56 ParkerVision, Inc. Inc. 17 Leap 57 QUALCOMM, Inc. 18 LG Telecom, Ltd. 58 QuickSilver Technologies 19 Mahanagar Telephone Nigam 59 Research Institute of Limited (MTNL) Telecommunication Transmission, MII (RITT) 1A Nextel Communications, 5A Schema, Ltd. Inc. 1B Operadora UNEFON SA de CV 5B SchlumbergerSema 1C Pacific Bangladesh 5C ScoreBoard, Inc. Telecom Limited 1D Pegaso PCS, S.A. DE C.V. 5D SignalSoft Corp. Carroll Expires - March 2004 [Page 34] Dynamic MIP Key Update September 2003 PKOID Public Key PKOID Public Key (HEX) Organization (PKO) (HEX) Organization (PKO) ----- ------------------ ----- ------------------ 1E Pele-Phone 5E SmartServ Online, Communications Ltd. Inc. 1F Qwest 5F TDK Corporation 20 Reliance Infocom Limited 60 Texas Instruments 21 Shinsegi Telecomm, Inc. 61 Wherify Wireless, Inc. 22 Shyam Telelink Limited 62 Acterna 23 SK Telecom 63 Anritsu Company 24 Sprint PCS 64 Ericsson 25 Tata Teleservices Ltd. 65 Grayson Wireless 26 Telecom Mobile Limited 66 LinkAir Communications, Inc. 27 Telstra Corporation 67 Racal Instruments Limited 28 Telus Mobility Cellular, 68 Rohde & Schwarz Inc. 29 US Cellular 69 Spirent Communications 2A 3G Cellular 6A Willtech, Inc. 2B Acer Communication & 6B Wireless Test Systems Multimedia Inc. 2C AirPrime, Inc. 6C Airvana, Inc. 2D Alpine Electronics, Inc. 6D COM DEV Wireless 2E Audiovox Communications 6E Conductus, Inc. Corporation 2F DENSO Wireless 6F Glenayre Electronics Inc. 30 Ditrans Corporation 70 Hitachi Telecom (USA), Inc. 31 Fujitsu Network 71 Hyundai Syscomm Inc. Communication, Inc. 32 Gemplus Corporation 72 ISCO 33 Giga Telecom Inc. 73 LG Electronics, Inc. 34 Hyundai CURITEL, Inc. 74 LinkAir Communications, Inc. 35 InnovICs Corp 75 Lucent Technologies, Inc. 36 Kyocera Corporation 76 Motorola CIG 37 LG Electronics, Inc. 77 Nortel Networks 38 LinkAir Communications, 78 Repeater Technologies Inc. 39 Motorola, Inc. 79 Samsung Electronics Co., Ltd. 3A Nokia Corporation 7A Starent Networks 3B Novatel Wireless, Inc. 7B Tahoe Networks, Inc. 3C OKI Network Technologies 7C Tantivy Communications, Inc. 3D Pixo 7D WaterCove Networks Carroll Expires - March 2004 [Page 35] Dynamic MIP Key Update September 2003 PKOID Public Key PKOID Public Key (HEX) Organization (PKO) (HEX) Organization (PKO) ----- ------------------ ----- ------------------ 3E Research In Motion 7E Winphoria Networks, Inc. 3F Samsung Electronics 7F ZTE Corporation Co., Ltd. Note: 80 through FF will be assigned by the PKOID administrator (TBD). Table 2. DMU Version DMU Version DMU Version Value ----------- ----------- 00 Version 1.3 01 TBD 02 TBD 03 TBD 04 TBD 05 TBD 06 TBD 07 Cleartext Mode Table 3. Algorithm Type and Version ATV Public Key Algorithm Value Type and Version ----- -------------------- 00 Reserved 01 RSA - 1024 02 RSA - 768 03 RSA - 2048 04 TBD 05 TBD 06 TBD 07 TBD 11. Intellectual Property Verizon Wireless has submitted a Patent Application to the United States Patent and Trademark Office for components of the DMU Procedure. Qualcomm Incorporated may have patents or copyrights that cover information contained in this document. Carroll Expires - March 2004 [Page 36] Dynamic MIP Key Update September 2003 12. Conclusion The Dynamic Mobile IP key Update (DMU) Procedure enables the efficient, yet secure, delivery of critical Mobile IP cryptographic keys. The use of cryptographic keys, hence the bootstrapping of such MIP keys using the DMU Procedure, is essential to commercial delivery of Mobile IP service in CDMA 2000 1xRTT and HRPD/1xEV-DO networks networks or other networks that utilize Mobile IP. 13. Formal Syntax None. References 1 Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, Internet Engineering Task Force, March 1997 2 TIA/EIA/IS-2000 Series, Revision A, Telecommunications Industry Association, March 2000 3 TIA/EIA/IS-856, cdma2000 High Rate Packet Data Air Interface Specification, Telecommunications Industry Association, November 2000 4 TIA/EIA/IS-835-A, cdma2000 Wireless IP Network Standard, Telecommunications Industry Association, May 2001 5 ANSI/TIA/EIA-41-D-97, Cellular Radiotelecommunications Intersystem Operations, Telecommunications Industry Association, December 1997 6 ANSI/TIA/EIA-683-B-2001, Over-the-Air Service Provisioning of Mobile Stations in Spread Spectrum Systems, Telecommunications Industry Association, December 2001 7 B. Kaliski. PKCS #1: RSA Encryption Version 1.5. RFC 2313, Internet Engineering Task Force, March 1998. 8 G. Dommety, K. Leung. Mobile IP Vendor/Organization-Specific Extensions. RFC 3115, Internet Engineering Task Force, April 2001 9 TIA/EIA-IS-634-A, Interoperability Specifications (IOS) for cdma2000 Access Network Interfaces, Telecommunications Industry Association, August 2001 Carroll Expires - March 2004 [Page 37] Dynamic MIP Key Update September 2003 10 D. Eastlake, 3rd, S. Crocker, and J. Schiller. Randomness Recommendations for Security. RFC 1750, Internet Engineering Task Force, December 1994. Acknowledgments Thanks to Jeffrey Dyck (Qualcomm), James Willkie (Qualcomm), Jayanth Mandayam (Qualcomm), Marcello Lioy (Qualcomm), Michael Borella (CommWorks), Cliff Randall (CommWorks), Daniel Cassinelli (CommWorks), Edward Dunn (CommWorks), Suresh Sarvepalli (CommWorks), Gabriella Ambramovici (Lucent), Semyon Mizikovsky (Lucent), Sarvar Patel (Lucent), Peter McCann (Lucent), Ganapathy Sundaram (Lucent), Girish Patel (Nortel), Glen Baxley (Nortel), Diane Thompson (Ericsson), Brian Hickman(Ericsson), Somsay Sychaleun (Bridgewater), Parm Sandhu (Sierra Wireless), Iulian Mucano (Sierra Wireless), and Samy Touati (Ericsson) for their useful discussions and comments. Author's Addresses Christopher Carroll Verizon Wireless 400 Friberg Parkway Westborough, MA 01581-3956 Phone: 508-330-3401 Email: Christoper.Carroll@verizonwireless.com Frank Quick Qualcomm Incorporated 5775 Morehouse Drive San Diego, CA 92121 USA Phone: 858-658-3608 Email: fquick@qualcomm.com Carroll Expires - March 2004 [Page 38] Dynamic MIP Key Update September 2003 14. Appendix - Cleartext-Mode Operation DMU MUST support a cleartext mode for development testing where DMUV = 7. The MIP_Key_Data payload will assume the same size as if RSA 1024-bit encryption were applied to the payload. In this mode, the MIP_Key_Data Radius Attribute and MIP Vendor Specific Extension will be 134 bytes and 138 bytes in length respectively. Thus, in cleartext mode, the payload MUST consist of 48 bytes of keys (MN_AAA, MN_HA, and CHAP key), 8 byte AAA_Authenticator, 3 byte MN_Authenticator. The next 69 bytes will be padded with "0" bits. MIP_Key_Data = MN_AAAh key, MN_HA key, CHAP_key, MN_Authenticator, AAA_Authenticator, Padding (69 bytes), Public_Key_IDi, DMUV Where: MN_AAA key = 128-bit random MN / AAA Server key. MN_HA key = 128-bit random MN / Home Agent (HA) key. CHAP_key = 128-bit random Simple IP authentication key. MN_Authenticator = 24-bit random number. AAA_Authenticator = 64-bit random number used by MN to authenticate AAA Server. Padding = 69 bytes of 0's. DMU Version (DMUV) = 4 bit identifier of DMU version. Public Key Identifier (Pub _Key_ID) = PKOID, PKOI, PK_Expansion, ATV Where: Public Key Organization Identifier (PKOID) = 8-bit serial number identifier of Public Key Organization (PKO) that created the Public Key. Public Key Organization Index (PKOI) = 8-bit serial number used at PKO discretion to distinguish different Public/Private key pairs. PK_Expansion = 8-bit field to enable possible expansion of PKOID or PKOI fields. (Note: Default value = 0xFF) Algorithm Type and Version (ATV) = 4-bit identifier of the algorithm used. Carroll Expires - March 2004 [Page 39]