DOC: Extend EVP_PKEYDSA(7) / EVP_PKEY_DH(7) with FFC information
Reviewedby: Paul Dale <paul.dale@oracle.com> (Merged from https://github.com/openssl/openssl/pull/11546)master
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@ 37,10 +37,20 @@ creating a key from user data.




EVP_PKEY_fromdata() creates the structure to store key parameters or a


key, given data from I<params> and a context that's been initialized with


EVP_PKEY_param_fromdata_init() or EVP_PKEY_key_fromdata_init(). The result


is written to I<*ppkey>. The parameters that can be used are specific to


the L<providerkeymgmt(7)> implementations, please see


L<EVP_PKEY_CTX_new_from_name(3)> for further information.


EVP_PKEY_param_fromdata_init() or EVP_PKEY_key_fromdata_init(). The result is


written to I<*ppkey>. The parameters that can be used for various types of key


are as described by the diverse "Common parameters" sections of the


L<B<EVP_PKEYRSA>(7)EVP_PKEYRSA(7)/Common RSA parameters>,


L<B<EVP_PKEYDSA>(7)EVP_PKEYDSA(7)/Common DSA & DH parameters>,


L<B<EVP_PKEYDH>(7)EVP_PKEYDH(7)/Common DH parameters>,


L<B<EVP_PKEYEC>(7)EVP_PKEYEC(7)/Common EC parameters>,


L<B<EVP_PKEYED448>(7)EVP_PKEYED448(7)/Common X25519, X448, ED25519 and ED448 parameters>,


L<B<EVP_PKEYX25519>(7)EVP_PKEYX25519(7)/Common X25519, X448, ED25519 and ED448 parameters>,


L<B<EVP_PKEYX448>(7)EVP_PKEYX448(7)/Common X25519, X448, ED25519 and ED448 parameters>,


and L<B<EVP_PKEYED25519>(7)EVP_PKEYED25519(7)/Common X25519, X448, ED25519 and ED448 parameters> pages.




=for comment the awful list of links above is made this way so we get nice


rendering as a manpage while still getting proper links in HTML




EVP_PKEY_param_fromdata_settable() and EVP_PKEY_key_fromdata_settable()


get a constant B<OSSL_PARAM> array that describes the settable parameters



@ 210,7 +220,10 @@ example with L<OSSL_PARAM_allocate_from_text(3)>.


=head1 SEE ALSO




L<EVP_PKEY_CTX_new(3)>, L<provider(7)>, L<EVP_PKEY_gettable_params(3)>,


L<OSSL_PARAM(3)>


L<OSSL_PARAM(3)>,


L<EVP_PKEYRSA(7)>, L<EVP_PKEYDSA(7)>, L<EVP_PKEYDH(7)>, L<EVP_PKEYEC(7)>,


L<EVP_PKEYED448(7)>, L<EVP_PKEYX25519(7)>, L<EVP_PKEYX448(7)>,


L<EVP_PKEYED25519(7)>




=head1 HISTORY





@ 218,7 +231,7 @@ These functions were added in OpenSSL 3.0.




=head1 COPYRIGHT




Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.


Copyright 20192020 The OpenSSL Project Authors. All Rights Reserved.




Licensed under the Apache License 2.0 (the "License"). You may not use


this file except in compliance with the License. You can obtain a copy





@ 10,10 +10,61 @@ EVP_PKEYDSA, EVP_KEYMGMTDSA, EVP_PKEYDH, EVP_KEYMGMTDH


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


DiffieHellman key establishment algorithms specified in SP80056A 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 safeprime


groups, and a class of "FIPS 186type" domain parameters. FIPS 186type domain


parameters should only be used for backward compatibility with existing


applications that cannot be upgraded to use the approved safeprime groups.




For B<DSA> (and B<DH> that is not a named group) the FIPS1864 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 "safeprimegenerator" (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<providerkeymgmt(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 DiffieHellman "p" value.


A DSA or DiffieHellman prime "p" value.




=item "q" (B<OSSL_PKEY_PARAM_FFC_Q>) <unsigned integer>




A DSA or DiffieHellman "q" value.


A DSA or DiffieHellman prime "q" value.




=item "g" (B<OSSL_PKEY_PARAM_FFC_G>) <unsigned integer>




A DSA or DiffieHellman "g" value.


A DSA or DiffieHellman 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 builtin 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 "safeprimegenerator" 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 "safeprimegenerator" (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 SP80056Ar3:




=over 4




=item 5.5.1.1 FFC Domain Parameter Selection/Generation




=item Appendix D: FFC Safeprime Groups




=back




The following sections of FIPS 1864:




=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






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