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OPENSSL-GENPKEY(1ossl)              OpenSSL             OPENSSL-GENPKEY(1ossl)



NAME

       openssl-genpkey - generate a private key or key pair


SYNOPSIS

       openssl genpkey [-help] [-out filename] [-outpubkey filename] [-outform
       DER|PEM] [-verbose] [-quiet] [-pass arg] [-cipher] [-paramfile file]
       [-algorithm alg] [-pkeyopt opt:value] [-genparam] [-text] [-engine id]
       [-provider name] [-provider-path path] [-propquery propq] [-config
       configfile]


DESCRIPTION

       This command generates a private key or key pair.


OPTIONS

       -help
           Print out a usage message.

       -out filename
           Output the private key to the specified file. If this argument is
           not specified then standard output is used.

       -outpubkey filename
           Output the public key to the specified file. If this argument is
           not specified then the public key is not output.

       -outform DER|PEM
           The output format, except when -genparam is given; the default is
           PEM.  See openssl-format-options(1) for details.

           When -genparam is given, -outform is ignored.

       -verbose
           Output "status dots" while generating keys.

       -quiet
           Do not output "status dots" while generating keys.

       -pass arg
           The output file password source. For more information about the
           format of arg see openssl-passphrase-options(1).

       -cipher
           This option encrypts the private key with the supplied cipher. Any
           algorithm name accepted by EVP_get_cipherbyname() is acceptable
           such as des3.

       -algorithm alg
           Public key algorithm to use such as RSA, DSA, DH or DHX. If used
           this option must precede any -pkeyopt options. The options
           -paramfile and -algorithm are mutually exclusive. Engines or
           providers 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
           -genparam option) are DH, DSA and EC.

           Note that the algorithm name X9.42 DH may be used as a synonym for
           DHX keys and PKCS#3 refers to DH Keys. Some options are not shared
           between DH and DHX keys.

       -pkeyopt opt:value
           Set the public key algorithm option opt to value. The precise set
           of options supported depends on the public key algorithm used and
           its implementation. See "KEY GENERATION OPTIONS" and "PARAMETER
           GENERATION OPTIONS" below for more details.

           To list the possible opt values for an algorithm use: openssl
           genpkey -algorithm XXX -help

       -genparam
           Generate a set of parameters instead of a private key. If used this
           option must precede any -algorithm, -paramfile or -pkeyopt options.

       -paramfile filename
           Some public key algorithms generate a private key based on a set of
           parameters.  They can be supplied using this option. If this option
           is used the public key algorithm used is determined by the
           parameters. If used this option must precede any -pkeyopt options.
           The options -paramfile and -algorithm are mutually exclusive.

       -text
           Print an (unencrypted) text representation of private and public
           keys and parameters along with the PEM or DER structure.

       -engine id
           See "Engine Options" in openssl(1).  This option is deprecated.

       -provider name
       -provider-path path
       -propquery propq
           See "Provider Options" in openssl(1), provider(7), and property(7).

       -config configfile
           See "Configuration Option" in openssl(1).


KEY 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. There are no key generation options defined for the
       X25519, X448, ED25519 or ED448 algorithms.

   RSA Key Generation Options
       rsa_keygen_bits:numbits
           The number of bits in the generated key. If not specified 2048 is
           used.

       rsa_keygen_primes:numprimes
           The number of primes in the generated key. If not specified 2 is
           used.

       rsa_keygen_pubexp:value
           The RSA public exponent value. This can be a large decimal or
           hexadecimal value if preceded by "0x". Default value is 65537.

   RSA-PSS Key Generation Options
       Note: by default an RSA-PSS key has no parameter restrictions.

       rsa_keygen_bits:numbits, rsa_keygen_primes:numprimes,
       rsa_keygen_pubexp:value
           These options have the same meaning as the RSA algorithm.

       rsa_pss_keygen_md:digest
           If set the key is restricted and can only use digest for signing.

       rsa_pss_keygen_mgf1_md:digest
           If set the key is restricted and can only use digest as it's MGF1
           parameter.

       rsa_pss_keygen_saltlen:len
           If set the key is restricted and len specifies the minimum salt
           length.

   EC Key Generation Options
       The EC key generation options can also be used for parameter
       generation.

       ec_paramgen_curve:curve
           The EC curve to use. OpenSSL supports NIST curve names such as
           "P-256".

       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.

   DH Key Generation Options
       group:name
           The paramfile option is not required if a named group is used here.
           See the "DH Parameter Generation Options" section below.


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.

   DSA Parameter Generation Options
       dsa_paramgen_bits:numbits
           The number of bits in the generated prime. If not specified 2048 is
           used.

       dsa_paramgen_q_bits:numbits
       qbits:numbits
           The number of bits in the q parameter. Must be one of 160, 224 or
           256. If not specified 224 is used.

       dsa_paramgen_md:digest
       digest:digest
           The digest to use during parameter generation. Must be one of sha1,
           sha224 or sha256. If set, then the number of bits in q will match
           the output size of the specified digest and the 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 q, i.e. sha1 if
           q length is 160, sha224 if it 224 or sha256 if it is 256.

       properties:query
           The digest property query string to use when fetching a digest from
           a provider.

       type:type
           The type of generation to use. Set this to 1 to use legacy
           FIPS186-2 parameter generation. The default of 0 uses FIPS186-4
           parameter generation.

       gindex:index
           The index to use for canonical generation and verification of the
           generator g.  Set this to a positive value ranging from 0..255 to
           use this mode. Larger values will only use the bottom byte.  This
           index must then be reused during key validation to verify the value
           of g.  If this value is not set then g is not verifiable. The
           default value is -1.

       hexseed:seed
           The seed seed data to use instead of generating a random seed
           internally.  This should be used for testing purposes only. This
           will either produced fixed values for the generated parameters OR
           it will fail if the seed did not generate valid primes.

   DH Parameter Generation Options
       For most use cases it is recommended to use the group option rather
       than the type options. Note that the group option is not used by
       default if no parameter generation options are specified.

       group:name
       dh_param:name
           Use a named DH group to select constant values for the DH
           parameters.  All other options will be ignored if this value is
           set.

           Valid values that are associated with the algorithm of "DH" are:
           "ffdhe2048", "ffdhe3072", "ffdhe4096", "ffdhe6144", "ffdhe8192",
           "modp_1536", "modp_2048", "modp_3072", "modp_4096", "modp_6144",
           "modp_8192".

           Valid values that are associated with the algorithm of "DHX" are
           the RFC5114 names "dh_1024_160", "dh_2048_224", "dh_2048_256".

       dh_rfc5114:num
           If this option is set, then the appropriate RFC5114 parameters are
           used instead of generating new parameters. The value num can be one
           of 1, 2 or 3 that are equivalent to using the option group with one
           of "dh_1024_160", "dh_2048_224" or "dh_2048_256".  All other
           options will be ignored if this value is set.

       pbits:numbits
       dh_paramgen_prime_len:numbits
           The number of bits in the prime parameter p. The default is 2048.

       qbits:numbits
       dh_paramgen_subprime_len:numbits
           The number of bits in the sub prime parameter q. The default is
           224.  Only relevant if used in conjunction with the
           dh_paramgen_type option to generate DHX parameters.

       safeprime-generator:value
       dh_paramgen_generator:value
           The value to use for the generator g. The default is 2.  The
           algorithm option must be "DH" for this parameter to be used.

       type:string
           The type name of DH parameters to generate. Valid values are:

           "generator"
               Use a safe prime generator with the option safeprime_generator
               The algorithm option must be "DH".

           "fips186_4"
               FIPS186-4 parameter generation.  The algorithm option must be
               "DHX".

           "fips186_2"
               FIPS186-4 parameter generation.  The algorithm option must be
               "DHX".

           "group"
               Can be used with the option pbits to select one of "ffdhe2048",
               "ffdhe3072", "ffdhe4096", "ffdhe6144" or "ffdhe8192".  The
               algorithm option must be "DH".

           "default"
               Selects a default type based on the algorithm. This is used by
               the OpenSSL default provider to set the type for backwards
               compatibility.  If algorithm is "DH" then "generator" is used.
               If algorithm is "DHX" then "fips186_2" is used.

       dh_paramgen_type:value
           The type of DH parameters to generate. Valid values are 0, 1, 2 or
           3 which correspond to setting the option type to "generator",
           "fips186_2", "fips186_4" or "group".

       digest:digest
           The digest to use during parameter generation. Must be one of sha1,
           sha224 or sha256. If set, then the number of bits in qbits will
           match the output size of the specified digest and the qbits
           parameter will be ignored. If not set, then a digest will be used
           that gives an output matching the number of bits in q, i.e. sha1 if
           q length is 160, sha224 if it is 224 or sha256 if it is 256.  This
           is only used by "fips186_4" and "fips186_2" key generation.

       properties:query
           The digest property query string to use when fetching a digest from
           a provider.  This is only used by "fips186_4" and "fips186_2" key
           generation.

       gindex:index
           The index to use for canonical generation and verification of the
           generator g.  Set this to a positive value ranging from 0..255 to
           use this mode. Larger values will only use the bottom byte.  This
           index must then be reused during key validation to verify the value
           of g.  If this value is not set then g is not verifiable. The
           default value is -1.  This is only used by "fips186_4" and
           "fips186_2" key generation.

       hexseed:seed
           The seed seed data to use instead of generating a random seed
           internally.  This should be used for testing purposes only. This
           will either produced fixed values for the generated parameters OR
           it will fail if the seed did not generate valid primes.  This is
           only used by "fips186_4" and "fips186_2" key generation.

   EC Parameter Generation Options
       The EC parameter generation options are the same as for key generation.
       See "EC Key Generation Options" above.


NOTES

       The use of the genpkey program is encouraged over the algorithm
       specific utilities because additional algorithm options and ENGINE
       provided algorithms can be used.


EXAMPLES

       Generate an RSA private key using default parameters:

        openssl genpkey -algorithm RSA -out key.pem

       Encrypt output private key using 128 bit AES and the passphrase
       "hello":

        openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello

       Generate a 2048 bit RSA key using 3 as the public exponent:

        openssl genpkey -algorithm RSA -out key.pem \
            -pkeyopt rsa_keygen_bits:2048 -pkeyopt rsa_keygen_pubexp:3

       Generate 2048 bit DSA parameters that can be validated: The output
       values for gindex and seed are required for key validation purposes and
       are not saved to the output pem file).

        openssl genpkey -genparam -algorithm DSA -out dsap.pem -pkeyopt pbits:2048 \
            -pkeyopt qbits:224 -pkeyopt digest:SHA256 -pkeyopt gindex:1 -text

       Generate DSA key from parameters:

        openssl genpkey -paramfile dsap.pem -out dsakey.pem

       Generate 4096 bit DH Key using safe prime group ffdhe4096:

        openssl genpkey -algorithm DH -out dhkey.pem -pkeyopt group:ffdhe4096

       Generate 2048 bit X9.42 DH key with 256 bit subgroup using RFC5114
       group3:

        openssl genpkey -algorithm DHX -out dhkey.pem -pkeyopt dh_rfc5114:3

       Generate a DH key using a DH parameters file:

        openssl genpkey -paramfile dhp.pem -out dhkey.pem

       Output DH parameters for safe prime group ffdhe2048:

        openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt group:ffdhe2048

       Output 2048 bit X9.42 DH parameters with 224 bit subgroup using RFC5114
       group2:

        openssl genpkey -genparam -algorithm DHX -out dhp.pem -pkeyopt dh_rfc5114:2

       Output 2048 bit X9.42 DH parameters with 224 bit subgroup using
       FIP186-4 keygen:

        openssl genpkey -genparam -algorithm DHX -out dhp.pem -text \
            -pkeyopt pbits:2048 -pkeyopt qbits:224 -pkeyopt digest:SHA256 \
            -pkeyopt gindex:1 -pkeyopt dh_paramgen_type:2

       Output 1024 bit X9.42 DH parameters with 160 bit subgroup using
       FIP186-2 keygen:

        openssl genpkey -genparam -algorithm DHX -out dhp.pem -text \
            -pkeyopt pbits:1024 -pkeyopt qbits:160 -pkeyopt digest:SHA1 \
            -pkeyopt gindex:1 -pkeyopt dh_paramgen_type:1

       Output 2048 bit DH parameters:

        openssl genpkey -genparam -algorithm DH -out dhp.pem \
            -pkeyopt dh_paramgen_prime_len:2048

       Output 2048 bit DH parameters using a generator:

        openssl genpkey -genparam -algorithm DH -out dhpx.pem \
            -pkeyopt dh_paramgen_prime_len:2048 \
            -pkeyopt dh_paramgen_type:1

       Generate EC parameters:

        openssl genpkey -genparam -algorithm EC -out ecp.pem \
               -pkeyopt ec_paramgen_curve:secp384r1 \
               -pkeyopt ec_param_enc:named_curve

       Generate EC key from parameters:

        openssl genpkey -paramfile ecp.pem -out eckey.pem

       Generate EC key directly:

        openssl genpkey -algorithm EC -out eckey.pem \
               -pkeyopt ec_paramgen_curve:P-384 \
               -pkeyopt ec_param_enc:named_curve

       Generate an X25519 private key:

        openssl genpkey -algorithm X25519 -out xkey.pem

       Generate an ED448 private key:

        openssl genpkey -algorithm ED448 -out xkey.pem


HISTORY

       The ability to use NIST curve names, and to generate an EC key
       directly, 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.

       The -engine option was deprecated in OpenSSL 3.0.


COPYRIGHT

       Copyright 2006-2023 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
       in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.

3.2.0                             2023-11-23            OPENSSL-GENPKEY(1ossl)

openssl 3.2.0 - Generated Wed Nov 29 08:16:21 CST 2023
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