openssl-ecparam

ECPARAM(1SSL)                       OpenSSL                      ECPARAM(1SSL)

NAME
       openssl-ecparam, ecparam - EC parameter manipulation and generation

SYNOPSIS
       openssl ecparam [-help] [-inform DER|PEM] [-outform DER|PEM] [-in
       filename] [-out filename] [-noout] [-text] [-C] [-check] [-name arg]
       [-list_curves] [-conv_form arg] [-param_enc arg] [-no_seed] [-rand
       file...]  [-writerand file] [-genkey] [-engine id]

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

OPTIONS
       -help
           Print out a usage message.

       -inform DER|PEM
           This specifies the input format. The DER option uses an ASN.1 DER
           encoded form compatible with RFC 3279 EcpkParameters. The PEM form
           is the default format: it consists of the DER format base64 encoded
           with additional header and footer lines.

       -outform DER|PEM
           This specifies the output format, the options have the same meaning
           and default as the -inform option.

       -in filename
           This specifies the input filename 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 should
           not be the same as the input filename.

       -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.

       -C  This option converts the EC parameters into C code. The parameters
           can then be loaded by calling the get_ec_group_XXX() function.

       -check
           Validate the elliptic curve parameters.

       -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
           If this options is specified ecparam will print out a list of all
           currently implemented EC parameters names and exit.

       -conv_form
           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.

       -rand file...
           A file or files containing random data used to seed the random
           number generator.  Multiple files can be specified separated by an
           OS-dependent character.  The separator is ; for MS-Windows, , for
           OpenVMS, and : for all others.

       [-writerand file]
           Writes random data to the specified file upon exit.  This can be
           used with a subsequent -rand flag.

       -engine id
           Specifying an engine (by its unique id string) will cause ecparam
           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.

NOTES
       PEM format EC parameters use the header and footer lines:

        -----BEGIN EC PARAMETERS-----
        -----END EC PARAMETERS-----

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

EXAMPLES
       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
       ec(1), dsaparam(1)

COPYRIGHT
       Copyright 2003-2018 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>.

1.1.1f                            2023-10-10                     ECPARAM(1SSL)