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