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>.

1.1.1                                              2023-05-24                                      ECPARAM(1SSL)