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209
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1 Tech Note 0006
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2 PK Standards Compliance
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3 Tom St Denis
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4
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5 RSA
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6 ----
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7
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8 PKCS #1 compliance.
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9
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10 Key Format: RSAPublicKey and RSAPrivateKey as per PKCS #1 v2.1
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11 Encryption: OAEP as per PKCS #1
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12 Signature : PSS as per PKCS #1
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13
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14 DSA
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15 ----
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16
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17 The NIST DSA algorithm
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18
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19 Key Format: HomeBrew [see below]
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20 Signature : ANSI X9.62 format [see below].
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21
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22 Keys are stored as
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23
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24 DSAPublicKey ::= SEQUENCE {
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25 publicFlags BIT STRING(1), -- must be 0
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26 g INTEGER , -- base generator, check that g^q mod p == 1
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27 -- and that 1 < g < p - 1
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28 p INTEGER , -- prime modulus
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29 q INTEGER , -- order of sub-group (must be prime)
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30 y INTEGER , -- public key, specifically, g^x mod p,
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31 -- check that y^q mod p == 1
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32 -- and that 1 < y < p - 1
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33 }
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34
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35 DSAPrivateKey ::= SEQUENCE {
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36 publicFlags BIT STRING(1), -- must be 1
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37 g INTEGER , -- base generator, check that g^q mod p == 1
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38 -- and that 1 < g < p - 1
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39 p INTEGER , -- prime modulus
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40 q INTEGER , -- order of sub-group (must be prime)
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41 y INTEGER , -- public key, specifically, g^x mod p,
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42 -- check that y^q mod p == 1
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43 -- and that 1 < y < p - 1
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44 x INTEGER -- private key
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45 }
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46
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47 Signatures are stored as
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48
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49 DSASignature ::= SEQUENCE {
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50 r, s INTEGER -- signature parameters
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51 }
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52
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53 ECC
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54 ----
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55
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56 The ANSI X9.62 and X9.63 algorithms [partial]. Supports all NIST GF(p) curves.
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57
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58 Key Format : Homebrew [see below, only GF(p) NIST curves supported]
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59 Signature : X9.62 compliant
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60 Encryption : Homebrew [based on X9.63, differs in that the public point is stored as an ECCPublicKey]
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61 Shared Secret: X9.63 compliant
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62
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63 ECCPublicKey ::= SEQUENCE {
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64 flags BIT STRING(1), -- public/private flag (always zero),
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65 keySize INTEGER, -- Curve size (in bits) divided by eight
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66 -- and rounded down, e.g. 521 => 65
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67 pubkey.x INTEGER, -- The X co-ordinate of the public key point
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68 pubkey.y INTEGER, -- The Y co-ordinate of the public key point
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69 }
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70
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71 ECCPrivateKey ::= SEQUENCE {
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72 flags BIT STRING(1), -- public/private flag (always one),
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73 keySize INTEGER, -- Curve size (in bits) divided by eight
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74 -- and rounded down, e.g. 521 => 65
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75 pubkey.x INTEGER, -- The X co-ordinate of the public key point
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76 pubkey.y INTEGER, -- The Y co-ordinate of the public key point
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77 secret.k INTEGER, -- The secret key scalar
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78 }
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79
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80 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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81 of the hash digest]. The format of the encrypted text is as follows
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82
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83 ECCEncrypted ::= SEQUENCE {
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84 hashOID OBJECT IDENTIFIER, -- The OID of the hash used
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85 pubkey OCTET STRING , -- Encapsulation of a random ECCPublicKey
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86 skey OCTET STRING -- The encrypted text (which the hash was XOR'ed against)
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87 }
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88
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89 % $Source: /cvs/libtom/libtomcrypt/notes/tech0006.txt,v $
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90 % $Revision: 1.2 $
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91 % $Date: 2005/06/18 02:26:27 $
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