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GENPKEY(1)			    OpenSSL			    GENPKEY(1)

NAME
       openssl-genpkey,	genpkey	- generate a private key

SYNOPSIS
       openssl genpkey [-help] [-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
       -help
	   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.	The default format is
	   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. 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
	   -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 dh_paramgen_type
	   option to indicate whether PKCS#3 or	X9.42 DH parameters are
	   required. See "DH Parameter Generation Options" below for more
	   details.

       -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.

       -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.

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 1024 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".

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 1024 is
	   used.

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

       dsa_paramgen_md: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.

   DH Parameter	Generation Options
       dh_paramgen_prime_len:numbits
	   The number of bits in the prime parameter p.	The default is 1024.

       dh_paramgen_subprime_len:numbits
	   The number of bits in the sub prime parameter 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 dh_paramgen_type option to
	   generate X9.42 DH parameters.

       dh_paramgen_generator:value
	   The value to	use for	the generator g. The default is	2.

       dh_paramgen_type:value
	   The type of DH parameters to	generate. Use 0	for PKCS#3 DH and 1
	   for X9.42 DH.  The default is 0.

       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.	If
	   present this	overrides all other DH parameter options.

   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:

	openssl	genpkey	-genparam -algorithm DSA -out dsap.pem \
	    -pkeyopt dsa_paramgen_bits:2048

       Generate	DSA key	from parameters:

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

       Generate	2048 bit DH parameters:

	openssl	genpkey	-genparam -algorithm DH	-out dhp.pem \
	    -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	-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

       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.

COPYRIGHT
       Copyright 2006-2018 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
       <https://www.openssl.org/source/license.html>.

1.1.1a				  2018-11-20			    GENPKEY(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | KEY GENERATION OPTIONS | PARAMETER GENERATION OPTIONS | NOTES | EXAMPLES | HISTORY | COPYRIGHT

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