DOC: Extend EVP_PKEY-DSA(7) / EVP_PKEY_DH(7) with FFC information

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/11546)

1 files changed, 207 insertions, 6 deletions

diff --git a/doc/man7/EVP_PKEY-DSA.pod b/doc/man7/EVP_PKEY-DSA.pod
index 307a46e019..ccb34a9f93 100644
--- a/doc/man7/EVP_PKEY-DSA.pod
+++ b/doc/man7/EVP_PKEY-DSA.pod
@@ -10,10 +10,61 @@ EVP_PKEY-DSA, EVP_KEYMGMT-DSA, EVP_PKEY-DH, EVP_KEYMGMT-DH
 The B<DSA> and B<DH> keytypes are implemented in OpenSSL's default and FIPS
 providers.
 The implementations support the basic DSA and DH keys, containing the public
-and private keys I<pub> and I<priv> as well as the three domain parameters
+and private keys I<pub> and I<priv> as well as the three main domain parameters
 I<p>, I<q> and I<g>.
 
-=head2 Common DSA / DH parameters
+Finite field cryptography (FFC) is a method of implementing discrete logarithm
+cryptography using finite field mathematics. DSA is an example of FFC and
+Diffie-Hellman key establishment algorithms specified in SP800-56A can also be
+implemented as FFC.
+
+For B<DH> FFC key agreement, two classes of domain parameters can be used:
+"safe" domain parameters that are associated with approved named safe-prime
+groups, and a class of "FIPS 186-type" domain parameters. FIPS 186-type domain
+parameters should only be used for backward compatibility with existing
+applications that cannot be upgraded to use the approved safe-prime groups.
+
+For B<DSA> (and B<DH> that is not a named group) the FIPS186-4 standard
+specifies that the values used for FFC parameter generation are also required
+for parameter validation.
+This means that optional FFC domain parameter values for I<seed>, I<pcounter>
+and I<gindex> may need to be stored for validation purposes.
+For B<DH> the I<seed> and I<pcounter> can be stored in ASN1 data
+(but the I<gindex> is not). For B<DSA> however, these fields are not stored in
+the ASN1 data so they need to be stored externally if validation is required.
+
+=head2 Common DH parameters
+
+=over 4
+
+=item "group" (B<OSSL_PKEY_PARAM_FFC_GROUP>) <UTF8 string>
+
+A string that associates a B<DH> named safe prime group with known values for
+I<p>, I<q> and I<g>.
+
+The following values can be used by the default and OpenSSL's FIPS providers:
+"ffdhe2048", "ffdhe3072", "ffdhe4096", "ffdhe6144", "ffdhe8192",
+"modp_2048", "modp_3072", "modp_4096", "modp_6144", "modp_8192".
+
+The following additional values can also be used by the default provider:
+"modp_1536", "dh_1024_160", "dh_2048_224", "dh_2048_256".
+
+DH named groups can be easily validated since the parameters are well known.
+For protocols that only transfer I<p> and I<g> the value of I<q> can also be
+retrieved.
+
+=item "safeprime-generator" (B<OSSL_PKEY_PARAM_FFC_GENERATOR>) <integer>
+
+Used for DH generation of safe primes using the old generator code.
+It is recommended to use a named safe prime group instead, if domain parameter
+validation is required. The default value is 2.
+
+These are not named safe prime groups so setting this value for the OpenSSL FIPS
+provider will instead choose a named safe prime group based on the size of I<p>.
+
+=back
+
+=head2 Common DSA & DH parameters
 
 In addition to the common parameters that all keytypes should support (see
 L<provider-keymgmt(7)/Common parameters>), the B<DSA> and B<DH> keytype
@@ -31,21 +82,171 @@ The private key value.
 
 =item "p" (B<OSSL_PKEY_PARAM_FFC_P>) <unsigned integer>
 
-A DSA or Diffie-Hellman "p" value.
+A DSA or Diffie-Hellman prime "p" value.
 
 =item "q" (B<OSSL_PKEY_PARAM_FFC_Q>) <unsigned integer>
 
-A DSA or Diffie-Hellman "q" value.
+A DSA or Diffie-Hellman prime "q" value.
 
 =item "g" (B<OSSL_PKEY_PARAM_FFC_G>) <unsigned integer>
 
-A DSA or Diffie-Hellman "g" value.
+A DSA or Diffie-Hellman generator "g" value.
+
+=item "seed" (B<OSSL_PKEY_PARAM_FFC_SEED>) <octet string>
+
+An optional domain parameter I<seed> value used during generation and validation
+of I<p>, I<q> and canonical I<g>.
+For validation this needs to set the I<seed> that was produced during generation.
+
+=item "gindex" (B<OSSL_PKEY_PARAM_FFC_GINDEX>) <integer>
+
+Sets the index to use for canonical generation and verification of the generator
+I<g>.
+Set this to a positive value from 0..FF to use this mode. This I<gindex> can
+then be reused during key validation to verify the value of I<g>. If this value
+is not set or is -1 then unverifiable generation of the generator I<g> will be
+used.
+
+=item "pcounter" (B<OSSL_PKEY_PARAM_FFC_PCOUNTER>) <integer>
+
+An optional domain parameter I<counter> value that is output during generation
+of I<p>. This value must be saved if domain parameter validation is required.
+
+=item "hindex" (B<OSSL_PKEY_PARAM_FFC_H>) <integer>
+
+For unverifiable generation of the generator I<g> this value is output during 
+generation of I<g>. Its value is the first integer larger than one that
+satisfies g = h^j mod p (where g != 1 and "j" is the cofactor).
+
+=item "j" (B<OSSL_PKEY_PARAM_FFC_COFACTOR>) <unsigned integer>
+
+An optional informational cofactor parameter that should equal (p - 1) / q.
 
 =back
 
+
+=head2 DSA / DH key generation (FFC) parameters
+
+The following Key Generation types are available for the built-in FFC algorithms:
+
+=over 4
+
+=item "type" (B<OSSL_PKEY_PARAM_FFC_TYPE>) <utf8_string>
+
+Sets the type of parameter generation. For DH Valid values are:
+
+=over 4
+
+=item "fips186_4"
+
+The current standard. This is the default value.
+
+=item "default"
+
+This is an alias to use the latest implemented standard.
+It is currently set to "fips186_4".
+
+=item "group"
+
+This specifies that a named safe prime name will be chosen using the "pbits"
+type.
+
+=item "fips186_2"
+
+The old standard that should only be used for legacy purposes.
+
+=item "generator"
+
+A safe prime generator. See the "safeprime-generator" type.
+
+=back
+
+For DSA valid values are one of "default", "fips186_4" or "fips186_2" as
+described above.
+
+=item "pbits" (B<OSSL_PKEY_PARAM_FFC_PBITS>) <unsigned integer>
+
+Sets the size (in bits) of the prime 'p'.
+
+For "fips186_4" this must be 2048 for DH, and either of 2048 or 3072 for DSA.
+For "fips186_2" this must be 1024.
+For "group" this can be any one of 2048, 3072, 4096, 6144 or 8192.
+
+=item "qbits" (B<OSSL_PKEY_PARAM_FFC_QBITS>) <unsigned integer>
+
+Sets the size (in bits) of the prime 'q'.
+
+For "fips186_4" this can be either 224 or 256.
+For "fips186_2" this has a size of 160.
+
+=item "digest" (B<OSSL_PKEY_PARAM_FFC_DIGEST>)  <utf8_string>
+
+Sets the Digest algorithm to be used as part of the Key Generation Function
+associated with the given Key Generation I<ctx>.
+This must also be set for key validation.
+
+=item "properties" (B<OSSL_PKEY_PARAM_FFC_DIGEST_PROPS>) <utf8_string>
+
+Sets properties to be used upon look up of the implementation for the selected
+Digest algorithm for the Key Generation Function associated with the given key
+generation I<ctx>. This may also be set for key validation.
+
+=item "seed" (B<OSSL_PKEY_PARAM_FFC_SEED>) <octet string>
+
+For "fips186_4" or "fips186_2" generation this sets the I<seed> data to use
+instead of generating a random seed internally. This should be used for
+testing purposes only. This will either produce fixed values for the generated
+parameters OR it will fail if the seed did not generate valid primes.
+
+=item "group" (B<OSSL_PKEY_PARAM_FFC_GROUP>) <UTF8 string>
+
+=item "safeprime-generator" (B<OSSL_PKEY_PARAM_FFC_GENERATOR>) <integer>
+
+=item "gindex" (B<OSSL_PKEY_PARAM_FFC_GINDEX>) <integer>
+
+=item "pcounter" (B<OSSL_PKEY_PARAM_FFC_PCOUNTER>) <integer>
+
+=item "hindex" (B<OSSL_PKEY_PARAM_FFC_H>) <integer>
+
+These types are described above.
+
+=back
+
+
 =head1 CONFORMING TO
 
-[TBA]
+=over 4
+
+=item RFC 7919 (TLS ffdhe named safe prime groups)
+
+=item RFC 3526 (IKE modp named safe prime groups)
+
+=item RFC 5114 (Additional DH named groups for dh_1024_160", "dh_2048_224"
+          and "dh_2048_256").
+
+=back
+
+The following sections of SP800-56Ar3:
+
+=over 4
+
+=item 5.5.1.1 FFC Domain Parameter Selection/Generation
+
+=item Appendix D: FFC Safe-prime Groups
+
+=back
+
+The following sections of FIPS 186-4:
+
+=over 4
+
+=item A.1.1.2 Generation of Probable Primes p and q Using an Approved Hash Function.
+
+=item A.2.3 Generation of canonical generator g.
+
+=item A.2.1 Unverifiable Generation of the Generator g.
+
+=back
 
 =head1 SEE ALSO