| Tech Note 0006 |
| PK Standards Compliance |
| Tom St Denis |
| |
| RSA |
| ---- |
| |
| PKCS #1 compliance. |
| |
| Key Format: RSAPublicKey and RSAPrivateKey as per PKCS #1 v2.1 |
| Encryption: OAEP as per PKCS #1 |
| Signature : PSS as per PKCS #1 |
| |
| DSA |
| ---- |
| |
| The NIST DSA algorithm |
| |
| Key Format: HomeBrew [see below] |
| Signature : ANSI X9.62 format [see below]. |
| |
| Keys are stored as |
| |
| DSAPublicKey ::= SEQUENCE { |
| publicFlags BIT STRING(1), -- must be 0 |
| g INTEGER , -- base generator, check that g^q mod p == 1 |
| -- and that 1 < g < p - 1 |
| p INTEGER , -- prime modulus |
| q INTEGER , -- order of sub-group (must be prime) |
| y INTEGER , -- public key, specifically, g^x mod p, |
| -- check that y^q mod p == 1 |
| -- and that 1 < y < p - 1 |
| } |
| |
| DSAPrivateKey ::= SEQUENCE { |
| publicFlags BIT STRING(1), -- must be 1 |
| g INTEGER , -- base generator, check that g^q mod p == 1 |
| -- and that 1 < g < p - 1 |
| p INTEGER , -- prime modulus |
| q INTEGER , -- order of sub-group (must be prime) |
| y INTEGER , -- public key, specifically, g^x mod p, |
| -- check that y^q mod p == 1 |
| -- and that 1 < y < p - 1 |
| x INTEGER -- private key |
| } |
| |
| Signatures are stored as |
| |
| DSASignature ::= SEQUENCE { |
| r, s INTEGER -- signature parameters |
| } |
| |
| ECC |
| ---- |
| |
| The ANSI X9.62 and X9.63 algorithms [partial]. Supports all NIST GF(p) curves. |
| |
| Key Format : Homebrew [see below, only GF(p) NIST curves supported] |
| Signature : X9.62 compliant |
| Encryption : Homebrew [based on X9.63, differs in that the public point is stored as an ECCPublicKey] |
| Shared Secret: X9.63 compliant |
| |
| ECCPublicKey ::= SEQUENCE { |
| flags BIT STRING(1), -- public/private flag (always zero), |
| keySize INTEGER, -- Curve size (in bits) divided by eight |
| -- and rounded down, e.g. 521 => 65 |
| pubkey.x INTEGER, -- The X co-ordinate of the public key point |
| pubkey.y INTEGER, -- The Y co-ordinate of the public key point |
| } |
| |
| ECCPrivateKey ::= SEQUENCE { |
| flags BIT STRING(1), -- public/private flag (always one), |
| keySize INTEGER, -- Curve size (in bits) divided by eight |
| -- and rounded down, e.g. 521 => 65 |
| pubkey.x INTEGER, -- The X co-ordinate of the public key point |
| pubkey.y INTEGER, -- The Y co-ordinate of the public key point |
| secret.k INTEGER, -- The secret key scalar |
| } |
| |
| The encryption works by finding the X9.63 shared secret and hashing it. The hash is then simply XOR'ed against the message [which must be at most the size |
| of the hash digest]. The format of the encrypted text is as follows |
| |
| ECCEncrypted ::= SEQUENCE { |
| hashOID OBJECT IDENTIFIER, -- The OID of the hash used |
| pubkey OCTET STRING , -- Encapsulation of a random ECCPublicKey |
| skey OCTET STRING -- The encrypted text (which the hash was XOR'ed against) |
| } |
| |
| % $Source: /cvs/libtom/libtomcrypt/notes/tech0006.txt,v $ |
| % $Revision: 1.2 $ |
| % $Date: 2005/06/18 02:26:27 $ |
