genpkey.1 revision 325335
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Title "GENPKEY 1"
GENPKEY 1 "2017-05-25" "1.0.2l" "OpenSSL"
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"NAME"
genpkey - generate a private key
"SYNOPSIS"
Header "SYNOPSIS" \fBopenssl genpkey [-out filename] [-outform PEM|DER] [-pass arg] [-cipher] [-engine id] [-paramfile file] [-algorithm alg] [-pkeyopt opt:value] [-genparam] [-text]
"DESCRIPTION"
Header "DESCRIPTION" The genpkey command generates a private key.
"OPTIONS"
Header "OPTIONS"
"-out filename" 4
Item "-out filename" the output filename. If this argument is not specified then standard output is used.
"-outform DER|PEM" 4
Item "-outform DER|PEM" This specifies the output format \s-1DER\s0 or \s-1PEM.\s0
"-pass arg" 4
Item "-pass arg" the output file password source. For more information about the format of arg see the \s-1PASS PHRASE ARGUMENTS\s0 section in openssl\|(1).
"-cipher" 4
Item "-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" 4
Item "-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" 4
Item "-algorithm alg" public key algorithm to use such as \s-1RSA, DSA\s0 or \s-1DH.\s0 If used this option must precede any -pkeyopt options. The options -paramfile and -algorithm are mutually exclusive.
"-pkeyopt opt:value" 4
Item "-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 \s-1KEY GENERATION OPTIONS\s0 below for more details.
"-genparam" 4
Item "-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" 4
Item "-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" 4
Item "-text" Print an (unencrypted) text representation of private and public keys and parameters along with the \s-1PEM\s0 or \s-1DER\s0 structure.
"KEY GENERATION OPTIONS"
Header "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"
Header "RSA KEY GENERATION OPTIONS"
"rsa_keygen_bits:numbits" 4
Item "rsa_keygen_bits:numbits" The number of bits in the generated key. If not specified 1024 is used.
"rsa_keygen_pubexp:value" 4
Item "rsa_keygen_pubexp:value" The \s-1RSA\s0 public exponent value. This can be a large decimal or hexadecimal value if preceded by 0x. Default value is 65537.
"DSA PARAMETER GENERATION OPTIONS"
Header "DSA PARAMETER GENERATION OPTIONS"
"dsa_paramgen_bits:numbits" 4
Item "dsa_paramgen_bits:numbits" The number of bits in the generated parameters. If not specified 1024 is used.
"DH PARAMETER GENERATION OPTIONS"
Header "DH PARAMETER GENERATION OPTIONS"
"dh_paramgen_prime_len:numbits" 4
Item "dh_paramgen_prime_len:numbits" The number of bits in the prime parameter p.
"dh_paramgen_generator:value" 4
Item "dh_paramgen_generator:value" The value to use for the generator g.
"dh_rfc5114:num" 4
Item "dh_rfc5114:num" If this option is set then the appropriate \s-1RFC5114\s0 parameters are used instead of generating new parameters. The value num can take the values 1, 2 or 3 corresponding to \s-1RFC5114 DH\s0 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 \s-1RFC5114\s0 sections 2.1, 2.2 and 2.3 respectively.
"EC PARAMETER GENERATION OPTIONS"
Header "EC PARAMETER GENERATION OPTIONS"
"ec_paramgen_curve:curve" 4
Item "ec_paramgen_curve:curve" the \s-1EC\s0 curve to use.
"GOST2001 KEY GENERATION AND PARAMETER OPTIONS"
Header "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 \s-1README\s0.gost file in the engines/ccgost directiry of the source distribution for more details.

Use of a parameter file for the \s-1GOST R 34.10\s0 algorithm is optional. Parameters can be specified during key generation directly as well as during generation of parameter file.

"paramset:name" 4
Item "paramset:name" Specifies \s-1GOST R 34.10-2001\s0 parameter set according to \s-1RFC 4357.\s0 Parameter set can be specified using abbreviated name, object short name or numeric \s-1OID.\s0 Following parameter sets are supported: .Sp .Vb 7 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 .Ve
"NOTES"
Header "NOTES" The use of the genpkey program is encouraged over the algorithm specific utilities because additional algorithm options and \s-1ENGINE\s0 provided algorithms can be used.
"EXAMPLES"
Header "EXAMPLES" Generate an \s-1RSA\s0 private key using default parameters:

.Vb 1 openssl genpkey -algorithm RSA -out key.pem .Ve

Encrypt output private key using 128 bit \s-1AES\s0 and the passphrase \*(L"hello\*(R":

.Vb 1 openssl genpkey -algorithm RSA -out key.pem -aes-128-cbc -pass pass:hello .Ve

Generate a 2048 bit \s-1RSA\s0 key using 3 as the public exponent:

.Vb 2 openssl genpkey -algorithm RSA -out key.pem -pkeyopt rsa_keygen_bits:2048 \e -pkeyopt rsa_keygen_pubexp:3 .Ve

Generate 1024 bit \s-1DSA\s0 parameters:

.Vb 2 openssl genpkey -genparam -algorithm DSA -out dsap.pem \e -pkeyopt dsa_paramgen_bits:1024 .Ve

Generate \s-1DSA\s0 key from parameters:

.Vb 1 openssl genpkey -paramfile dsap.pem -out dsakey.pem .Ve

Generate 1024 bit \s-1DH\s0 parameters:

.Vb 2 openssl genpkey -genparam -algorithm DH -out dhp.pem \e -pkeyopt dh_paramgen_prime_len:1024 .Ve

Output \s-1RFC5114 2048\s0 bit \s-1DH\s0 parameters with 224 bit subgroup:

.Vb 1 openssl genpkey -genparam -algorithm DH -out dhp.pem -pkeyopt dh_rfc5114:2 .Ve

Generate \s-1DH\s0 key from parameters:

.Vb 1 openssl genpkey -paramfile dhp.pem -out dhkey.pem .Ve