Network Working Group A. Malpani (ValiCert)
Category: INTERNET-DRAFT October 1999
Expires April 2000
The NULL Public Key Algorithm (NPKA)
<draft-malpani-npka-00.txt>
Status of this Memo
This document is an Internet-Draft and is in full conformance
with all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
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Comments on this draft should be sent to ietf-pkix@imc.org.
Copyright Notice
Copyright (C) The Internet Society (1998). All Rights Reserved.
Abstract
This memo defines the NULL public key algorithm. The original goal
of this effort was to be able to allow people to optionally sign
data, without needing the make the signature optional in the ASN.1.
While we were at it, we decided to, for completeness, also specify
the method for NULL public key encryption.
1. Introduction
This memo defines the NULL public key algorithm. It explains how NPKA
NULL algorithm should be used both for digital signatures and
encryption/key exchange.
Despite the fact that we are not lawyers, we are relatively confident
that it is quite safe to use this algorithm for export for any key
length size. It is also quite impossible for people to discover your
private key via timing, power analysis or other cryptographic
methods, as long as you are only using this algorithm.
2. Algorithm Details
2.1 Algorithm Definition
In this section, we will show how NPKA can be used for both digital
signatures and key exchange. We use the following notation:
B represents the puBlic key
V represents the priVate key
C is the Clear text message
E is the Encrypted message
S is the Signing algorithm
G is the siGnature verification algorithm
Y is the key/data encrYption algorithm
D is the key/data decryption algorithm
F{x, y} is the function F on data elements x and y
2.1.1 Digital Signatures
This section shows how a private key is used to create a digital
signature and a public key used to verify the digital signature.
For signatures, the holder of the private key uses the message and
the private key to produce a digital signature, which can be verified
by anyone with the holder's public key.
S{C, V} => C
G{E, B} => E
Note: This satisfies the property required by all public key
signature algorithms - G{S{C, V}, B} => C
2.1.2 Encryption/Key Exchange
This section shows how a public key is used to encrypt data/keys
and a public key used to decrypt the data.
Y{C, B} => C
D{E, V} => E
Note: This satisfies the property required by all public key
encryption algorithms - D{Y{C, B}, V} => C
2.2 Keying Material
Like other modern ciphers, e.g., RC5 [RFC-2040], NPKA
can make use of keys of varying lengths. However, no
measurable increase in security is afforded by the use of longer key
lengths.
2.3 Padding
NULL has a block size of 1 byte, thus padding is not necessary.
2.4. Performance
The NULL encryption algorithm is significantly faster than other
commonly used symmetric encryption algorithms and implementations of
the base algorithm are available for all commonly used hardware and
OS platforms.
2.5 Test Vectors
[TBD]
We should also show what a cert with an NPKA signature looks like
3. Object Identifiers
[TBD]
We need to create the OIDs for sha1withNPKA, md4withNPKA, ...
4. Operational Requirements
[TBD]
5. Security Considerations
If you do implement this algorithm, please make sure that signatures
using that algorithm are only accepted in places where you do not need
signatures. Similarly, encryption with this algorithm is only performed
where you do not want encryption.
6. Algorithm properties
In this section, we try to outline the main properties of NPKA.
- Very, very high performance for both encryption and decryption,
for key exchange and signing.
- No export restrictions (for any key length).
- No risk of exposing your private key to any potential attacks.
- Short key sizes are as strong as keys twice as long.
- Small algorithm footprint - excellent for smart card support or other
low memory devices.
- Support for any sized key.
- Can easily be used in both a block or streaming mode.
- Great synchronization properties - loss of a single bit in transmission
results in only a single bit loss at the receiver (?)
7. Intellectual Property Rights
[TBD]
8. Acknowledgments
Spiritual and textual guidance for this document we provided by
[RFC2410].
9. References
[RFC-2410] Glenn R., and Kent, S., "The NULL Encryption Algorithm and
Its Use With IPsec", RFC 2410, November 1998.
10. Editors' Addresses
Ambarish Malpani
ValiCert, Inc.
1215 Terra Bella,
Mountain View, CA 94043
EMail: ambarish@valicert.com
Phone: 650.567.5457
11. Full Copyright Statement
Copyright (C) The Internet Society (1998). All Rights Reserved.
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Expires April 2000