1=pod
2
3=head1 NAME
4
5openssl-ecparam,
6ecparam - EC parameter manipulation and generation
7
8=head1 SYNOPSIS
9
10B<openssl ecparam>
11[B<-help>]
12[B<-inform DER|PEM>]
13[B<-outform DER|PEM>]
14[B<-in filename>]
15[B<-out filename>]
16[B<-noout>]
17[B<-text>]
18[B<-C>]
19[B<-check>]
20[B<-name arg>]
21[B<-list_curves>]
22[B<-conv_form arg>]
23[B<-param_enc arg>]
24[B<-no_seed>]
25[B<-rand file...>]
26[B<-writerand file>]
27[B<-genkey>]
28[B<-engine id>]
29
30=head1 DESCRIPTION
31
32This command is used to manipulate or generate EC parameter files.
33
34=head1 OPTIONS
35
36=over 4
37
38=item B<-help>
39
40Print out a usage message.
41
42=item B<-inform DER|PEM>
43
44This specifies the input format. The B<DER> option uses an ASN.1 DER encoded
45form compatible with RFC 3279 EcpkParameters. The PEM form is the default
46format: it consists of the B<DER> format base64 encoded with additional
47header and footer lines.
48
49=item B<-outform DER|PEM>
50
51This specifies the output format, the options have the same meaning and default
52as the B<-inform> option.
53
54=item B<-in filename>
55
56This specifies the input filename to read parameters from or standard input if
57this option is not specified.
58
59=item B<-out filename>
60
61This specifies the output filename parameters to. Standard output is used
62if this option is not present. The output filename should B<not> be the same
63as the input filename.
64
65=item B<-noout>
66
67This option inhibits the output of the encoded version of the parameters.
68
69=item B<-text>
70
71This option prints out the EC parameters in human readable form.
72
73=item B<-C>
74
75This option converts the EC parameters into C code. The parameters can then
76be loaded by calling the get_ec_group_XXX() function.
77
78=item B<-check>
79
80Validate the elliptic curve parameters.
81
82=item B<-name arg>
83
84Use the EC parameters with the specified 'short' name. Use B<-list_curves>
85to get a list of all currently implemented EC parameters.
86
87=item B<-list_curves>
88
89If this options is specified B<ecparam> will print out a list of all
90currently implemented EC parameters names and exit.
91
92=item B<-conv_form>
93
94This specifies how the points on the elliptic curve are converted
95into octet strings. Possible values are: B<compressed>, B<uncompressed> (the
96default value) and B<hybrid>. For more information regarding
97the point conversion forms please read the X9.62 standard.
98B<Note> Due to patent issues the B<compressed> option is disabled
99by default for binary curves and can be enabled by defining
100the preprocessor macro B<OPENSSL_EC_BIN_PT_COMP> at compile time.
101
102=item B<-param_enc arg>
103
104This specifies how the elliptic curve parameters are encoded.
105Possible value are: B<named_curve>, i.e. the ec parameters are
106specified by an OID, or B<explicit> where the ec parameters are
107explicitly given (see RFC 3279 for the definition of the
108EC parameters structures). The default value is B<named_curve>.
109B<Note> the B<implicitlyCA> alternative, as specified in RFC 3279,
110is currently not implemented in OpenSSL.
111
112=item B<-no_seed>
113
114This option inhibits that the 'seed' for the parameter generation
115is included in the ECParameters structure (see RFC 3279).
116
117=item B<-genkey>
118
119This option will generate an EC private key using the specified parameters.
120
121=item B<-rand file...>
122
123A file or files containing random data used to seed the random number
124generator.
125Multiple files can be specified separated by an OS-dependent character.
126The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
127all others.
128
129=item [B<-writerand file>]
130
131Writes random data to the specified I<file> upon exit.
132This can be used with a subsequent B<-rand> flag.
133
134=item B<-engine id>
135
136Specifying an engine (by its unique B<id> string) will cause B<ecparam>
137to attempt to obtain a functional reference to the specified engine,
138thus initialising it if needed. The engine will then be set as the default
139for all available algorithms.
140
141=back
142
143=head1 NOTES
144
145PEM format EC parameters use the header and footer lines:
146
147 -----BEGIN EC PARAMETERS-----
148 -----END EC PARAMETERS-----
149
150OpenSSL is currently not able to generate new groups and therefore
151B<ecparam> can only create EC parameters from known (named) curves.
152
153=head1 EXAMPLES
154
155To create EC parameters with the group 'prime192v1':
156
157  openssl ecparam -out ec_param.pem -name prime192v1
158
159To create EC parameters with explicit parameters:
160
161  openssl ecparam -out ec_param.pem -name prime192v1 -param_enc explicit
162
163To validate given EC parameters:
164
165  openssl ecparam -in ec_param.pem -check
166
167To create EC parameters and a private key:
168
169  openssl ecparam -out ec_key.pem -name prime192v1 -genkey
170
171To change the point encoding to 'compressed':
172
173  openssl ecparam -in ec_in.pem -out ec_out.pem -conv_form compressed
174
175To print out the EC parameters to standard output:
176
177  openssl ecparam -in ec_param.pem -noout -text
178
179=head1 SEE ALSO
180
181L<ec(1)>, L<dsaparam(1)>
182
183=head1 COPYRIGHT
184
185Copyright 2003-2018 The OpenSSL Project Authors. All Rights Reserved.
186
187Licensed under the OpenSSL license (the "License").  You may not use
188this file except in compliance with the License.  You can obtain a copy
189in the file LICENSE in the source distribution or at
190L<https://www.openssl.org/source/license.html>.
191
192=cut
193