doc/man7/EVP_PKEY-FFC.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 EVP_PKEY-FFC - EVP_PKEY DSA and DH shared FFC parameters.
   6
   7 =head1 DESCRIPTION
   8
   9 Finite field cryptography (FFC) is a method of implementing discrete logarithm
  10 cryptography using finite field mathematics. DSA is an example of FFC and
  11 Diffie-Hellman key establishment algorithms specified in SP800-56A can also be
  12 implemented as FFC.
  13
  14 The B<DSA> and B<DH> keytypes are implemented in OpenSSL's default and FIPS
  15 providers.
  16 The implementations support the basic DSA and DH keys, containing the public
  17 and private keys I<pub> and I<priv> as well as the three main domain parameters
  18 I<p>, I<q> and I<g>.
  19
  20 For B<DSA> (and B<DH> that is not a named group) the FIPS186-4 standard
  21 specifies that the values used for FFC parameter generation are also required
  22 for parameter validation.
  23 This means that optional FFC domain parameter values for I<seed>, I<pcounter>
  24 and I<gindex> may need to be stored for validation purposes.
  25 For B<DH> the I<seed> and I<pcounter> can be stored in ASN1 data
  26 (but the I<gindex> is not). For B<DSA> however, these fields are not stored in
  27 the ASN1 data so they need to be stored externally if validation is required.
  28
  29 =head2 FFC parameters
  30
  31 In addition to the common parameters that all keytypes should support (see
  32 L<provider-keymgmt(7)/Common parameters>), the B<DSA> and B<DH> keytype
  33 implementations support the following.
  34
  35 =over 4
  36
  37 =item "pub" (B<OSSL_PKEY_PARAM_PUB_KEY>) <unsigned integer>
  38
  39 The public key value.
  40
  41 =item "priv" (B<OSSL_PKEY_PARAM_PRIV_KEY>) <unsigned integer>
  42
  43 The private key value.
  44
  45 =item "p" (B<OSSL_PKEY_PARAM_FFC_P>) <unsigned integer>
  46
  47 A DSA or Diffie-Hellman prime "p" value.
  48
  49 =item "q" (B<OSSL_PKEY_PARAM_FFC_Q>) <unsigned integer>
  50
  51 A DSA or Diffie-Hellman prime "q" value.
  52
  53 =item "g" (B<OSSL_PKEY_PARAM_FFC_G>) <unsigned integer>
  54
  55 A DSA or Diffie-Hellman generator "g" value.
  56
  57 =item "seed" (B<OSSL_PKEY_PARAM_FFC_SEED>) <octet string>
  58
  59 An optional domain parameter I<seed> value used during generation and validation
  60 of I<p>, I<q> and canonical I<g>.
  61 For validation this needs to set the I<seed> that was produced during generation.
  62
  63 =item "gindex" (B<OSSL_PKEY_PARAM_FFC_GINDEX>) <integer>
  64
  65 Sets the index to use for canonical generation and verification of the generator
  66 I<g>.
  67 Set this to a positive value from 0..FF to use this mode. This I<gindex> can
  68 then be reused during key validation to verify the value of I<g>. If this value
  69 is not set or is -1 then unverifiable generation of the generator I<g> will be
  70 used.
  71
  72 =item "pcounter" (B<OSSL_PKEY_PARAM_FFC_PCOUNTER>) <integer>
  73
  74 An optional domain parameter I<counter> value that is output during generation
  75 of I<p>. This value must be saved if domain parameter validation is required.
  76
  77 =item "hindex" (B<OSSL_PKEY_PARAM_FFC_H>) <integer>
  78
  79 For unverifiable generation of the generator I<g> this value is output during
  80 generation of I<g>. Its value is the first integer larger than one that
  81 satisfies g = h^j mod p (where g != 1 and "j" is the cofactor).
  82
  83 =item "j" (B<OSSL_PKEY_PARAM_FFC_COFACTOR>) <unsigned integer>
  84
  85 An optional informational cofactor parameter that should equal to (p - 1) / q.
  86
  87 =back
  88
  89 =head2 FFC key generation parameters
  90
  91 The following key generation types are available for DSA and DH algorithms:
  92
  93 =over 4
  94
  95 =item "type" (B<OSSL_PKEY_PARAM_FFC_TYPE>) <utf8_string>
  96
  97 Sets the type of parameter generation. The shared valid values are:
  98
  99 =over 4
 100
 101 =item "fips186_4"
 102
 103 The current standard.
 104
 105 =item "fips186_2"
 106
 107 The old standard that should only be used for legacy purposes.
 108
 109 =item "default"
 110
 111 This can choose one of "fips186_4" or "fips186_2" depending on other
 112 parameters set for parameter generation.
 113
 114 =back
 115
 116 =item "pbits" (B<OSSL_PKEY_PARAM_FFC_PBITS>) <unsigned integer>
 117
 118 Sets the size (in bits) of the prime 'p'.
 119
 120 =item "qbits" (B<OSSL_PKEY_PARAM_FFC_QBITS>) <unsigned integer>
 121
 122 Sets the size (in bits) of the prime 'q'.
 123
 124 For "fips186_4" this can be either 224 or 256.
 125 For "fips186_2" this has a size of 160.
 126
 127 =item "digest" (B<OSSL_PKEY_PARAM_FFC_DIGEST>)  <utf8_string>
 128
 129 Sets the Digest algorithm to be used as part of the Key Generation Function
 130 associated with the given Key Generation I<ctx>.
 131 This must also be set for key validation.
 132
 133 =item "properties" (B<OSSL_PKEY_PARAM_FFC_DIGEST_PROPS>) <utf8_string>
 134
 135 Sets properties to be used upon look up of the implementation for the selected
 136 Digest algorithm for the Key Generation Function associated with the given key
 137 generation I<ctx>. This may also be set for key validation.
 138
 139 =item "seed" (B<OSSL_PKEY_PARAM_FFC_SEED>) <octet string>
 140
 141 For "fips186_4" or "fips186_2" generation this sets the I<seed> data to use
 142 instead of generating a random seed internally. This should be used for
 143 testing purposes only. This will either produce fixed values for the generated
 144 parameters OR it will fail if the seed did not generate valid primes.
 145
 146 =item "gindex" (B<OSSL_PKEY_PARAM_FFC_GINDEX>) <integer>
 147
 148 =item "pcounter" (B<OSSL_PKEY_PARAM_FFC_PCOUNTER>) <integer>
 149
 150 =item "hindex" (B<OSSL_PKEY_PARAM_FFC_H>) <integer>
 151
 152 These types are described above.
 153
 154 =back
 155
 156 =head1 CONFORMING TO
 157
 158 The following sections of SP800-56Ar3:
 159
 160 =over 4
 161
 162 =item 5.5.1.1 FFC Domain Parameter Selection/Generation
 163
 164 =back
 165
 166 The following sections of FIPS 186-4:
 167
 168 =over 4
 169
 170 =item A.1.1.2 Generation of Probable Primes p and q Using an Approved Hash Function.
 171
 172 =item A.2.3 Generation of canonical generator g.
 173
 174 =item A.2.1 Unverifiable Generation of the Generator g.
 175
 176 =back
 177
 178 =head1 SEE ALSO
 179
 180 L<EVP_PKEY-DSA(7)>,
 181 L<EVP_PKEY-DH(7)>,
 182 L<EVP_SIGNATURE-DSA(7)>,
 183 L<EVP_KEYEXCH-DH(7)>
 184 L<EVP_KEYMGMT(3)>,
 185 L<EVP_PKEY(3)>,
 186 L<provider-keymgmt(7)>,
 187 L<OSSL_PROVIDER-default(7)>,
 188 L<OSSL_PROVIDER-FIPS(7)>,
 189
 190 =head1 COPYRIGHT
 191
 192 Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
 193
 194 Licensed under the Apache License 2.0 (the "License").  You may not use
 195 this file except in compliance with the License.  You can obtain a copy
 196 in the file LICENSE in the source distribution or at
 197 L<https://www.openssl.org/source/license.html>.
 198
 199 =cut