Document when a session gets removed from cache

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

diff --git a/doc/apps/dhparam.pod b/doc/apps/dhparam.pod
index 59d1f68300ccd817120735866e00fe02b737784f..018d9935085a3e4e2d1d3a95629b32c87dd24bb6 100644 (file)
--- a/doc/apps/dhparam.pod
+++ b/doc/apps/dhparam.pod
@@ -2,22 +2,26 @@
 
 =head1 NAME
 
 
 =head1 NAME
 

+openssl-dhparam,

 dhparam - DH parameter manipulation and generation
 
 =head1 SYNOPSIS
 
 dhparam - DH parameter manipulation and generation
 
 =head1 SYNOPSIS
 

-B<openssl dh>
+B<openssl dhparam>

 [B<-inform DER|PEM>]
 [B<-outform DER|PEM>]
 [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<-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
 
 
 =head1 DESCRIPTION
 


@@ -39,35 +43,55 @@ additional header and footer lines.
 This specifies the output format, the options have the same meaning as the 
 B<-inform> option.
 
 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.
 
 
 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.
 
 
 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>
 
 =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
 
 a file or files containing random data used to seed the random number

-generator. Multiple files can be specified separated by a OS-dependent
-character.  For MS-Windows, the separator is B<;>.  For OpenVMS, it's
-B<,>. For all others, it's B<:>.
+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 B<numbits>
+=item I<numbits>

 
 this option specifies that a parameter set should be generated of size
 
 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>
 
 
 =item B<-noout>
 


@@ -80,7 +104,14 @@ 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
 =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
 
 
 =back
 


@@ -109,6 +140,11 @@ There should be a way to generate and manipulate DH keys.
 
 =head1 SEE ALSO
 
 
 =head1 SEE ALSO
 

-dsaparam(1)
+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
 
 =cut