GENPKEY(1)			    OpenSSL			    GENPKEY(1)



NAME
       genpkey - generate a private key

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

DESCRIPTION
       The genpkey command generates a private key.

OPTIONS
       -out filename
	   the output filename. 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).

       -cipher
	   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
	   details.

       -genparam
	   generate a set of parameters instead of a private key. If used this
	   option must precede and -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 and -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.

KEY GENERATION OPTIONS
       The options supported by each algorith and indeed each implementation
       of an algorithm can vary. The options for the OpenSSL implementations
       are detailed below.

RSA KEY GENERATION OPTIONS
       rsa_keygen_bits:numbits
	   The number of bits in the generated key. If not specified 1024 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.

DSA PARAMETER GENERATION OPTIONS
       dsa_paramgen_bits:numbits
	   The number of bits in the generated parameters. If not specified
	   1024 is used.

DH PARAMETER GENERATION OPTIONS
       dh_paramgen_prime_len:numbits
	   The number of bits in the prime parameter p.

       dh_paramgen_generator:value
	   The value to use for the generator g.

       dh_rfc5114:num
	   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.

EC PARAMETER GENERATION OPTIONS
       ec_paramgen_curve:curve
	   the EC curve to use.

GOST2001 KEY GENERATION AND PARAMETER OPTIONS
       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 directiry 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.

       paramset:name
	   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:

	     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

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 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



1.0.2k				  2017-01-26			    GENPKEY(1)