151 lines
4.0 KiB
Plaintext
151 lines
4.0 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
openssl-dhparam,
|
|
dhparam - DH parameter manipulation and generation
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
B<openssl dhparam>
|
|
[B<-inform DER|PEM>]
|
|
[B<-outform DER|PEM>]
|
|
[B<-in> I<filename>]
|
|
[B<-out> I<filename>]
|
|
[B<-dsaparam>]
|
|
[B<-check>]
|
|
[B<-noout>]
|
|
[B<-text>]
|
|
[B<-C>]
|
|
[B<-2>]
|
|
[B<-5>]
|
|
[B<-rand> I<file(s)>]
|
|
[B<-engine id>]
|
|
[I<numbits>]
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
This command is used to manipulate DH parameter files.
|
|
|
|
=head1 OPTIONS
|
|
|
|
=over 4
|
|
|
|
=item B<-inform DER|PEM>
|
|
|
|
This specifies the input format. The B<DER> option uses an ASN1 DER encoded
|
|
form compatible with the PKCS#3 DHparameter structure. The PEM form is the
|
|
default format: it consists of the B<DER> format base64 encoded with
|
|
additional header and footer lines.
|
|
|
|
=item B<-outform DER|PEM>
|
|
|
|
This specifies the output format, the options have the same meaning as the
|
|
B<-inform> option.
|
|
|
|
=item B<-in> I<filename>
|
|
|
|
This specifies the input filename to read parameters from or standard input if
|
|
this option is not specified.
|
|
|
|
=item B<-out> I<filename>
|
|
|
|
This specifies the output filename parameters to. Standard output is used
|
|
if this option is not present. The output filename should B<not> be the same
|
|
as the input filename.
|
|
|
|
=item B<-dsaparam>
|
|
|
|
If this option is used, DSA rather than DH parameters are read or created;
|
|
they are converted to DH format. Otherwise, "strong" primes (such
|
|
that (p-1)/2 is also prime) will be used for DH parameter generation.
|
|
|
|
DH parameter generation with the B<-dsaparam> option is much faster,
|
|
and the recommended exponent length is shorter, which makes DH key
|
|
exchange more efficient. Beware that with such DSA-style DH
|
|
parameters, a fresh DH key should be created for each use to
|
|
avoid small-subgroup attacks that may be possible otherwise.
|
|
|
|
=item B<-check>
|
|
|
|
check if the parameters are valid primes and generator.
|
|
|
|
=item B<-2>, B<-5>
|
|
|
|
The generator to use, either 2 or 5. If present then the
|
|
input file is ignored and parameters are generated instead. If not
|
|
present but B<numbits> is present, parameters are generated with the
|
|
default generator 2.
|
|
|
|
=item B<-rand> I<file(s)>
|
|
|
|
a file or files containing random data used to seed the random number
|
|
generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
|
|
Multiple files can be specified separated by a OS-dependent character.
|
|
The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
|
|
all others.
|
|
|
|
=item I<numbits>
|
|
|
|
this option specifies that a parameter set should be generated of size
|
|
I<numbits>. It must be the last option. If this option is present then
|
|
the input file is ignored and parameters are generated instead. If
|
|
this option is not present but a generator (B<-2> or B<-5>) is
|
|
present, parameters are generated with a default length of 2048 bits.
|
|
|
|
=item B<-noout>
|
|
|
|
this option inhibits the output of the encoded version of the parameters.
|
|
|
|
=item B<-text>
|
|
|
|
this option prints out the DH parameters in human readable form.
|
|
|
|
=item B<-C>
|
|
|
|
this option converts the parameters into C code. The parameters can then
|
|
be loaded by calling the B<get_dh>I<numbits>B<()> function.
|
|
|
|
=item B<-engine id>
|
|
|
|
specifying an engine (by its unique B<id> string) will cause B<dhparam>
|
|
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.
|
|
|
|
=back
|
|
|
|
=head1 WARNINGS
|
|
|
|
The program B<dhparam> combines the functionality of the programs B<dh> and
|
|
B<gendh> in previous versions of OpenSSL and SSLeay. The B<dh> and B<gendh>
|
|
programs are retained for now but may have different purposes in future
|
|
versions of OpenSSL.
|
|
|
|
=head1 NOTES
|
|
|
|
PEM format DH parameters use the header and footer lines:
|
|
|
|
-----BEGIN DH PARAMETERS-----
|
|
-----END DH PARAMETERS-----
|
|
|
|
OpenSSL currently only supports the older PKCS#3 DH, not the newer X9.42
|
|
DH.
|
|
|
|
This program manipulates DH parameters not keys.
|
|
|
|
=head1 BUGS
|
|
|
|
There should be a way to generate and manipulate DH keys.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<dsaparam(1)|dsaparam(1)>
|
|
|
|
=head1 HISTORY
|
|
|
|
The B<dhparam> command was added in OpenSSL 0.9.5.
|
|
The B<-dsaparam> option was added in OpenSSL 0.9.6.
|
|
|
|
=cut
|