Manual: openssl-ecparam

OPENSSL-ECPARAM(1SSL)					   OpenSSL				       OPENSSL-ECPARAM(1SSL)

NAME
       openssl-ecparam - EC parameter manipulation and generation

SYNOPSIS
       openssl ecparam [-help] [-inform DER|PEM] [-outform DER|PEM] [-in filename] [-out filename] [-noout] [-text] [-check]
       [-check_named] [-name arg] [-list_curves] [-conv_form arg] [-param_enc arg] [-no_seed] [-genkey] [-engine id] [-rand
       files] [-writerand file] [-provider name] [-provider-path path] [-provparam [name:]key=value] [-propquery propq]

DESCRIPTION
       This command is used to manipulate or generate EC parameter files.

       OpenSSL is currently not able to generate new groups and therefore this command can only create EC parameters from
       known (named) curves.

OPTIONS
       -help
	   Print out a usage message.

       -inform DER|PEM
	   The EC parameters input format; unspecified by default.  See openssl-format-options(1) for details.

       -outform DER|PEM
	   The EC parameters output format; the default is PEM.	 See openssl-format-options(1) for details.

	   Parameters are encoded as EcpkParameters as specified in IETF RFC 3279.

       -in filename
	   This specifies the input file to read parameters from or standard input if this option is not specified.

       -out filename
	   This	 specifies  the	 output	 filename parameters to. Standard output is used if this option is not present.	 The
	   output filename can be the same as the input filename, which leads to replacing the	file  contents.	  Note	that
	   file I/O is not atomic. The output file is truncated and then written.

       -noout
	   This option inhibits the output of the encoded version of the parameters.

       -text
	   This option prints out the EC parameters in human readable form.

       -check
	   Validate the elliptic curve parameters.

       -check_named
	   Validate the elliptic name curve parameters by checking if the curve parameters match any built-in curves.

       -name arg
	   Use	the  EC	 parameters  with  the	specified  'short'  name.  Use	-list_curves  to get a list of all currently
	   implemented EC parameters.

       -list_curves
	   Print out a list of all currently implemented EC parameters names and exit.

       -conv_form arg
	   This specifies how the points on the elliptic curve are  converted  into  octet  strings.  Possible	values	are:
	   compressed,	uncompressed  (the  default  value)  and hybrid. For more information regarding the point conversion
	   forms please read the X9.62 standard.  Note Due to patent issues the compressed option is disabled by default for
	   binary curves and can be enabled by defining the preprocessor macro OPENSSL_EC_BIN_PT_COMP at compile time.

       -param_enc arg
	   This specifies how the elliptic curve parameters are encoded.  Possible  value  are:	 named_curve,  i.e.  the  ec
	   parameters  are  specified  by an OID, or explicit where the ec parameters are explicitly given (see RFC 3279 for
	   the definition of the EC parameters structures).  The  default  value  is  named_curve.   Note  the	implicitlyCA
	   alternative, as specified in RFC 3279, is currently not implemented in OpenSSL.

       -no_seed
	   This	 option inhibits that the 'seed' for the parameter generation is included in the ECParameters structure (see
	   RFC 3279).

       -genkey
	   This option will generate an EC private key using the specified parameters.

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

       -rand files, -writerand file
	   See "Random State Options" in openssl(1) for details.

       -provider name
       -provider-path path
       -provparam [name:]key=value
       -propquery propq
	   See "Provider Options" in openssl(1), provider(7), and property(7).

       The openssl-genpkey(1) and openssl-pkeyparam(1) commands are capable of performing all the  operations  this  command
       can, as well as supporting other public key types.

EXAMPLES
       The  documentation  for	the openssl-genpkey(1) and openssl-pkeyparam(1) commands contains examples equivalent to the
       ones listed here.

       To create EC parameters with the group 'prime192v1':

	 openssl ecparam -out ec_param.pem -name prime192v1

       To create EC parameters with explicit parameters:

	 openssl ecparam -out ec_param.pem -name prime192v1 -param_enc explicit

       To validate given EC parameters:

	 openssl ecparam -in ec_param.pem -check

       To create EC parameters and a private key:

	 openssl ecparam -out ec_key.pem -name prime192v1 -genkey

       To change the point encoding to 'compressed':

	 openssl ecparam -in ec_in.pem -out ec_out.pem -conv_form compressed

       To print out the EC parameters to standard output:

	 openssl ecparam -in ec_param.pem -noout -text

SEE ALSO
       openssl(1), openssl-pkeyparam(1), openssl-genpkey(1), openssl-ec(1), openssl-dsaparam(1)

HISTORY
       The -engine option was deprecated in OpenSSL 3.0.

       The -C option was removed in OpenSSL 3.0.

COPYRIGHT
       Copyright 2003-2021 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
       .

3.5.5							 2026-01-27				       OPENSSL-ECPARAM(1SSL)