[ Contents ]
9. Constants
This section describes the constants used in OpenPGP.
Note that these tables are not exhaustive lists; an implementation
MAY implement an algorithm not on these lists.
See the section "Notes on Algorithms" below for more discussion of
the algorithms.
9.1. Public Key Algorithms
ID Algorithm
-- ---------
1 - RSA (Encrypt or Sign)
2 - RSA Encrypt-Only
3 - RSA Sign-Only
16 - Elgamal (Encrypt-Only), see [ELGAMAL]
17 - DSA (Digital Signature Standard)
18 - Reserved for Elliptic Curve
19 - Reserved for ECDSA
20 - Elgamal (Encrypt or Sign)
21 - Reserved for Diffie-Hellman (X9.42,
as defined for IETF-S/MIME)
100 to 110 - Private/Experimental algorithm.
Implementations MUST implement DSA for signatures, and Elgamal for
encryption. Implementations SHOULD implement RSA keys.
Implementations MAY implement any other algorithm.
9.2. Symmetric Key Algorithms
ID Algorithm
-- ---------
0 - Plaintext or unencrypted data
1 - IDEA [IDEA]
2 - Triple-DES (DES-EDE, as per spec -
168 bit key derived from 192)
3 - CAST5 (128 bit key, as per RFC 2144)
4 - Blowfish (128 bit key, 16 rounds) [BLOWFISH]
5 - SAFER-SK128 (13 rounds) [SAFER]
6 - Reserved for DES/SK
7 - Reserved for AES with 128-bit key
8 - Reserved for AES with 192-bit key
9 - Reserved for AES with 256-bit key
[WG: 10 - Twofish with 256-bit key].
100 to 110 - Private/Experimental algorithm.
Implementations MUST implement Triple-DES. Implementations SHOULD
implement IDEA and CAST5.Implementations MAY implement any other
algorithm.
9.3. Compression Algorithms
ID Algorithm
-- ---------
0 - Uncompressed
1 - ZIP (RFC 1951)
2 - ZLIB (RFC 1950)
100 to 110 - Private/Experimental algorithm.
Implementations MUST implement uncompressed data. Implementations
SHOULD implement ZIP. Implementations MAY implement ZLIB.
9.4. Hash Algorithms
ID Algorithm Text Name
-- --------- ---- ----
1 - MD5 "MD5"
2 - SHA-1 "SHA1"
3 - RIPE-MD/160 "RIPEMD160"
4 - Reserved for double-width SHA (experimental)
5 - MD2 "MD2"
6 - Reserved for TIGER/192 "TIGER192"
7 - Reserved for HAVAL (5 pass, 160-bit)
"HAVAL-5-160"
100 to 110 - Private/Experimental algorithm.
Implementations MUST implement SHA-1. Implementations SHOULD
implement MD5.
Updated: 1999-09-30 wkoch