Public key algorithm to use such as RSA, DSA or DH. If used this option must
precede any B<-pkeyopt> options. The options B<-paramfile> and B<-algorithm>
-are mutually exclusive.
+are mutually exclusive. Engines may add algorithms in addition to the standard
+built-in ones.
+
+Valid built-in algorithm names for private key generation are RSA, RSA-PSS, EC,
+X25519, X448, ED25519 and ED448.
+
+Valid built-in algorithm names for parameter generation (see the B<-genparam>
+option) are DH, DSA and EC.
+
+Note that the algorithm name X9.42 DH may be used as a synonym for the DH
+algorithm. These are identical and do not indicate the type of parameters that
+will be generated. Use the B<dh_paramgen_type> option to indicate whether PKCS#3
+or X9.42 DH parameters are required. See L<DH Parameter Generation Options>
+below for more details.
=item B<-pkeyopt opt:value>
Set the public key algorithm option B<opt> to B<value>. The precise set of
options supported depends on the public key algorithm used and its
-implementation. See B<KEY GENERATION OPTIONS> below for more details.
+implementation. See L<KEY GENERATION OPTIONS> and
+L<PARAMETER GENERATION OPTIONS> below for more details.
=item B<-genparam>
The options supported by each algorithm and indeed each implementation of an
algorithm can vary. The options for the OpenSSL implementations are detailed
-below.
+below. There are no key generation options defined for the X25519, X448, ED25519
+or ED448 algorithms.
-=head1 RSA KEY GENERATION OPTIONS
+=head2 RSA Key Generation Options
=over 4
=back
-=head1 RSA-PSS KEY GENERATION OPTIONS
+=head2 RSA-PSS Key Generation Options
Note: by default an B<RSA-PSS> key has no parameter restrictions.
=over 4
-=item B<rsa_keygen_bits:numbits>, B<rsa_keygen_pubexp:value>
-
-These options have the same meaning as the B<RSA> algorithm.
-
-=item B<rsa_pss_keygen_md:digest>
-
-=item B<rsa_keygen_pubexp:value>
-
-The RSA public exponent value. This can be a large decimal or
-hexadecimal value if preceded by B<0x>. Default value is 65537.
-
-=back
-
-=head1 RSA-PSS KEY GENERATION OPTIONS
-
-Note: by default an B<RSA-PSS> key has no parameter restrictions.
-
-=over 4
-
-=item B<rsa_keygen_bits:numbits>, B<rsa_keygen_pubexp:value>
+=item B<rsa_keygen_bits:numbits>, B<rsa_keygen_primes:numprimes>, B<rsa_keygen_pubexp:value>
These options have the same meaning as the B<RSA> algorithm.
=back
-=head1 DSA PARAMETER GENERATION OPTIONS
+=head2 EC Key Generation Options
+
+The EC key generation options can also be used for parameter generation.
=over 4
-=item B<dsa_paramgen_bits:numbits>
+=item B<ec_paramgen_curve:curve>
-The number of bits in the generated parameters. If not specified 1024 is used.
+The EC curve to use. OpenSSL supports NIST curve names such as "P-256".
+
+=item B<ec_param_enc:encoding>
+
+The encoding to use for parameters. The "encoding" parameter must be either
+"named_curve" or "explicit". The default value is "named_curve".
=back
-=head1 DH PARAMETER GENERATION OPTIONS
+=head1 PARAMETER GENERATION OPTIONS
+
+The options supported by each algorithm and indeed each implementation of an
+algorithm can vary. The options for the OpenSSL implementations are detailed
+below.
+
+=head2 DSA Parameter Generation Options
=over 4
-=item B<dh_paramgen_prime_len:numbits>
+=item B<dsa_paramgen_bits:numbits>
-The number of bits in the prime parameter B<p>.
+The number of bits in the generated prime. If not specified 1024 is used.
-=item B<dh_paramgen_generator:value>
+=item B<dsa_paramgen_q_bits:numbits>
-The value to use for the generator B<g>.
+The number of bits in the q parameter. Must be one of 160, 224 or 256. If not
+specified 160 is used.
-=item B<dh_rfc5114:num>
+=item B<dsa_paramgen_md:digest>
-If this option is set then the appropriate RFC5114 parameters are used
-instead of generating new parameters. The value B<num> can take the
-values 1, 2 or 3 corresponding to RFC5114 DH parameters consisting of
-1024 bit group with 160 bit subgroup, 2048 bit group with 224 bit subgroup
-and 2048 bit group with 256 bit subgroup as mentioned in RFC5114 sections
-2.1, 2.2 and 2.3 respectively.
+The digest to use during parameter generation. Must be one of B<sha1>, B<sha224>
+or B<sha256>. If set, then the number of bits in B<q> will match the output size
+of the specified digest and the B<dsa_paramgen_q_bits> parameter will be
+ignored. If not set, then a digest will be used that gives an output matching
+the number of bits in B<q>, i.e. B<sha1> if q length is 160, B<sha224> if it 224
+or B<sha256> if it is 256.
=back
-=head1 EC PARAMETER GENERATION OPTIONS
-
-The EC parameter generation options below can also
-be supplied as EC key generation options. This can (for example) generate a
-key from a named curve without the need to use an explicit parameter file.
+=head2 DH Parameter Generation Options
=over 4
-=item B<ec_paramgen_curve:curve>
-
-The EC curve to use. OpenSSL supports NIST curve names such as "P-256".
-
-=item B<ec_param_enc:encoding>
+=item B<dh_paramgen_prime_len:numbits>
-The encoding to use for parameters. The "encoding" parameter must be either
-"named_curve" or "explicit".
+The number of bits in the prime parameter B<p>. The default is 1024.
-=back
+=item B<dh_paramgen_subprime_len:numbits>
-=head1 GOST2001 KEY GENERATION AND PARAMETER OPTIONS
+The number of bits in the sub prime parameter B<q>. The default is 256 if the
+prime is at least 2048 bits long or 160 otherwise. Only relevant if used in
+conjunction with the B<dh_paramgen_type> option to generate X9.42 DH parameters.
-Gost 2001 support is not enabled by default. To enable this algorithm,
-one should load the ccgost engine in the OpenSSL configuration file.
-See README.gost file in the engines/ccgost directory of the source
-distribution for more details.
+=item B<dh_paramgen_generator:value>
-Use of a parameter file for the GOST R 34.10 algorithm is optional.
-Parameters can be specified during key generation directly as well as
-during generation of parameter file.
+The value to use for the generator B<g>. The default is 2.
-=over 4
+=item B<dh_paramgen_type:value>
-=item B<paramset:name>
+The type of DH parameters to generate. Use 0 for PKCS#3 DH and 1 for X9.42 DH.
+The default is 0.
-Specifies GOST R 34.10-2001 parameter set according to RFC 4357.
-Parameter set can be specified using abbreviated name, object short name or
-numeric OID. Following parameter sets are supported:
+=item B<dh_rfc5114:num>
- paramset OID Usage
- A 1.2.643.2.2.35.1 Signature
- B 1.2.643.2.2.35.2 Signature
- C 1.2.643.2.2.35.3 Signature
- XA 1.2.643.2.2.36.0 Key exchange
- XB 1.2.643.2.2.36.1 Key exchange
- test 1.2.643.2.2.35.0 Test purposes
+If this option is set, then the appropriate RFC5114 parameters are used
+instead of generating new parameters. The value B<num> can take the
+values 1, 2 or 3 corresponding to RFC5114 DH parameters consisting of
+1024 bit group with 160 bit subgroup, 2048 bit group with 224 bit subgroup
+and 2048 bit group with 256 bit subgroup as mentioned in RFC5114 sections
+2.1, 2.2 and 2.3 respectively. If present this overrides all other DH parameter
+options.
=back
-=head1 X25519 and X448 KEY GENERATION OPTIONS
+=head2 EC Parameter Generation Options
-The X25519 and X448 algorithms do not currently support any key generation
-options.
+The EC parameter generation options are the same as for key generation. See
+L<EC Key Generation Options> above.
=head1 NOTES
openssl genpkey -algorithm RSA -out key.pem -pkeyopt rsa_keygen_bits:2048 \
-pkeyopt rsa_keygen_pubexp:3
-Generate 1024 bit DSA parameters:
+Generate 2048 bit DSA parameters:
openssl genpkey -genparam -algorithm DSA -out dsap.pem \
- -pkeyopt dsa_paramgen_bits:1024
+ -pkeyopt dsa_paramgen_bits:2048
Generate DSA key from parameters:
openssl genpkey -paramfile dsap.pem -out dsakey.pem
-Generate 1024 bit DH parameters:
+Generate 2048 bit DH parameters:
openssl genpkey -genparam -algorithm DH -out dhp.pem \
- -pkeyopt dh_paramgen_prime_len:1024
+ -pkeyopt dh_paramgen_prime_len:2048
+
+Generate 2048 bit X9.42 DH parameters:
+
+ openssl genpkey -genparam -algorithm DH -out dhpx.pem \
+ -pkeyopt dh_paramgen_prime_len:2048 \
+ -pkeyopt dh_paramgen_type:1
Output RFC5114 2048 bit DH parameters with 224 bit subgroup:
openssl genpkey -algorithm X25519 -out xkey.pem
+Generate an ED448 private key:
+
+ openssl genpkey -algorithm ED448 -out xkey.pem
+
=head1 HISTORY
The ability to use NIST curve names, and to generate an EC key directly,
-were added in OpenSSL 1.0.2.
+were added in OpenSSL 1.0.2. The ability to generate X25519 keys was added in
+OpenSSL 1.1.0. The ability to generate X448, ED25519 and ED448 keys was added in
+OpenSSL 1.1.1.
=head1 COPYRIGHT
projects / oweals / openssl.git / commitdiff