openssl genpkey [-help] [-out filename] [-outform PEM|DER] [-pass arg]
       [-cipher] [-engine id] [-paramfile file] [-algorithm alg] [-pkeyopt
       opt:value] [-genparam] [-text]

       The genpkey command generates a private key.

           Print out a usage message.

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

       -outform DER|PEM
           This specifies the output format DER or PEM.

       -pass arg
           the output file password source. For more information about the
           format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).

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

       -engine id
           specifying an engine (by its unique id string) will cause genpkey
           to attempt to obtain a functional reference to the specified
           engine, thus initialising it if needed. The engine will then be set
           as the default for all available algorithms. If used this option
           should precede all other options.

       -algorithm alg
           public key algorithm to use such as RSA, DSA or DH. If used this
           option must precede any -pkeyopt options. The options -paramfile
           and -algorithm are mutually exclusive.

       -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 below for more

           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 number of bits in the generated key. If not specified 1024 is

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

           The number of bits in the generated parameters. If not specified
           1024 is used.

           The number of bits in the prime parameter p.

           The value to use for the generator g.

           If this option is set then the appropriate RFC5114 parameters are
           used instead of generating new parameters. The value 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 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.

           the EC curve to use. OpenSSL supports NIST curve names such as

           the encoding to use for parameters. The "encoding" parameter must
           be either "named_curve" or "explicit".

       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.

       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.

           Specifies GOST R 34.10-2001 parameter set according to RFC 4357.
           Parameter set can be specified using abbreviated name, object short


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

       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

        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 1024 bit DSA parameters:

        openssl genpkey -genparam -algorithm DSA -out dsap.pem \
                                                       -pkeyopt dsa_paramgen_bits:1024

       Generate DSA key from parameters:

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

       Generate 1024 bit DH parameters:

        openssl genpkey -genparam -algorithm DH -out dhp.pem \
                                               -pkeyopt dh_paramgen_prime_len:1024

       Output RFC5114 2048 bit DH parameters with 224 bit subgroup:

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

       Generate DH key from parameters:

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

       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

       directly, were added in OpenSSL 1.0.2.

       Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (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

1.1.0h                            2018-05-12                     GENPKEY(1SSL)
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