Match SUITEB strings at start of cipher list.

[openssl.git] / doc / apps / dhparam.pod

diff --git a/doc/apps/dhparam.pod b/doc/apps/dhparam.pod
index 6b237ec05a99c1e309a71236e8ab74baf1cfaa51..8bb196dea498c1d36b27f2c9702b8176289e32b5 100644 (file)
--- a/doc/apps/dhparam.pod
+++ b/doc/apps/dhparam.pod
@@ -6,18 +6,21 @@ dhparam - DH parameter manipulation and generation
 
 =head1 SYNOPSIS
 
-B<openssl dh>
+B<openssl dhparam>
 [B<-inform DER|PEM>]
 [B<-outform DER|PEM>]
-[B<-in filename>]
-[B<-out filename>]
+[B<-in> I<filename>]
+[B<-out> I<filename>]
+[B<-dsaparam>]
+[B<-check>]
 [B<-noout>]
 [B<-text>]
 [B<-C>]
 [B<-2>]
 [B<-5>]
-[B<-rand file(s)>]
-[numbits]
+[B<-rand> I<file(s)>]
+[B<-engine id>]
+[I<numbits>]
 
 =head1 DESCRIPTION
 
@@ -39,36 +42,55 @@ additional header and footer lines.
 This specifies the output format, the options have the same meaning as the 
 B<-inform> option.
 
-=item B<-in filename>
+=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 filename>
+=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. 2 is the default. If present then the
-input file is ignored and parameters are generated instead.
+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 file(s)>
+=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)>).
+generator, or an EGD socket (see L<RAND_egd(3)>).
 Multiple files can be specified separated by a OS-dependent character.
-The separator is B<;> for MS-Windows, B<,> for OpenVSM, and B<:> for
+The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
 all others.
 
-=item B<numbits>
+=item I<numbits>
 
 this option specifies that a parameter set should be generated of size
-B<numbits>. It must be the last option. If not present then a value of 512
-is used. If this option is present then the input file is ignored and 
-parameters are generated instead.
+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>
 
@@ -81,7 +103,14 @@ 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_dhXXX()> function.
+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
 
@@ -110,6 +139,11 @@ There should be a way to generate and manipulate DH keys.
 
 =head1 SEE ALSO
 
-L<dsaparam(1)|dsaparam(1)>
+L<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