5 openssl-ecparam - EC parameter manipulation and generation
11 [B<-inform> B<DER>|B<PEM>]
12 [B<-outform> B<DER>|B<PEM>]
22 [B<-conv_form> I<arg>]
23 [B<-param_enc> I<arg>]
26 [B<-writerand> I<file>]
30 =for comment ifdef engine
34 This command is used to manipulate or generate EC parameter files.
42 Print out a usage message.
44 =item B<-inform> B<DER>|B<PEM>
46 This specifies the input format. The B<DER> option uses an ASN.1 DER encoded
47 form compatible with RFC 3279 EcpkParameters. The PEM form is the default
48 format: it consists of the B<DER> format base64 encoded with additional
49 header and footer lines.
51 =item B<-outform> B<DER>|B<PEM>
53 This specifies the output format, the options have the same meaning and default
54 as the B<-inform> option.
56 =item B<-in> I<filename>
58 This specifies the input filename to read parameters from or standard input if
59 this option is not specified.
61 =item B<-out> I<filename>
63 This specifies the output filename parameters to. Standard output is used
64 if this option is not present. The output filename should B<not> be the same
65 as the input filename.
69 This option inhibits the output of the encoded version of the parameters.
73 This option prints out the EC parameters in human readable form.
77 This option converts the EC parameters into C code. The parameters can then
78 be loaded by calling the get_ec_group_XXX() function.
82 Validate the elliptic curve parameters.
86 Validate the elliptic name curve parameters by checking if the curve parameters
87 match any built-in curves.
91 Use the EC parameters with the specified 'short' name. Use B<-list_curves>
92 to get a list of all currently implemented EC parameters.
96 If this options is specified B<ecparam> will print out a list of all
97 currently implemented EC parameters names and exit.
101 This specifies how the points on the elliptic curve are converted
102 into octet strings. Possible values are: B<compressed>, B<uncompressed> (the
103 default value) and B<hybrid>. For more information regarding
104 the point conversion forms please read the X9.62 standard.
105 B<Note> Due to patent issues the B<compressed> option is disabled
106 by default for binary curves and can be enabled by defining
107 the preprocessor macro B<OPENSSL_EC_BIN_PT_COMP> at compile time.
109 =item B<-param_enc> I<arg>
111 This specifies how the elliptic curve parameters are encoded.
112 Possible value are: B<named_curve>, i.e. the ec parameters are
113 specified by an OID, or B<explicit> where the ec parameters are
114 explicitly given (see RFC 3279 for the definition of the
115 EC parameters structures). The default value is B<named_curve>.
116 B<Note> the B<implicitlyCA> alternative, as specified in RFC 3279,
117 is currently not implemented in OpenSSL.
121 This option inhibits that the 'seed' for the parameter generation
122 is included in the ECParameters structure (see RFC 3279).
126 This option will generate an EC private key using the specified parameters.
128 =item B<-rand> I<files>
130 The files containing random data used to seed the random number generator.
131 Multiple files can be specified separated by an OS-dependent character.
132 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
135 =item B<-writerand> I<file>
137 Writes random data to the specified I<file> upon exit.
138 This can be used with a subsequent B<-rand> flag.
140 =item B<-engine> I<id>
142 Specifying an engine (by its unique B<id> string) will cause B<ecparam>
143 to attempt to obtain a functional reference to the specified engine,
144 thus initialising it if needed. The engine will then be set as the default
145 for all available algorithms.
151 PEM format EC parameters use the header and footer lines:
153 -----BEGIN EC PARAMETERS-----
154 -----END EC PARAMETERS-----
156 OpenSSL is currently not able to generate new groups and therefore
157 B<ecparam> can only create EC parameters from known (named) curves.
161 To create EC parameters with the group 'prime192v1':
163 openssl ecparam -out ec_param.pem -name prime192v1
165 To create EC parameters with explicit parameters:
167 openssl ecparam -out ec_param.pem -name prime192v1 -param_enc explicit
169 To validate given EC parameters:
171 openssl ecparam -in ec_param.pem -check
173 To create EC parameters and a private key:
175 openssl ecparam -out ec_key.pem -name prime192v1 -genkey
177 To change the point encoding to 'compressed':
179 openssl ecparam -in ec_in.pem -out ec_out.pem -conv_form compressed
181 To print out the EC parameters to standard output:
183 openssl ecparam -in ec_param.pem -noout -text
189 L<openssl-dsaparam(1)>
193 Copyright 2003-2019 The OpenSSL Project Authors. All Rights Reserved.
195 Licensed under the Apache License 2.0 (the "License"). You may not use
196 this file except in compliance with the License. You can obtain a copy
197 in the file LICENSE in the source distribution or at
198 L<https://www.openssl.org/source/license.html>.