Document DSA and SHA.

New function BN_pseudo_rand().
Use BN_prime_checks_size(BN_num_bits(w)) rounds of Miller-Rabin when
generating DSA primes (why not use BN_is_prime()?)

doc/crypto/DSA_generate_parameters.pod

@@ -0,0 +1,94 @@
+=pod
+
+=head1 NAME
+
+DSA_generate_parameters - Generate DSA parameters
+
+=head1 SYNOPSIS
+
+ #include <openssl/dsa.h>
+
+ DSA *	DSA_generate_parameters(int bits, unsigned char *seed,
+                int seed_len, int *counter_ret, unsigned long *h_ret,
+		void (*callback)(), void *cb_arg);
+
+=head1 DESCRIPTION
+
+DSA_generate_parameters() generates primes p and q and a generator g
+for use in the DSA.
+
+B<bits> is the length of the prime to be generated; the DSS allows a
+maximum of 1024 bits.
+
+If B<seed> is NULL or B<seed_len> E<lt> 20, the primes will be
+generated at random. Otherwise, the seed is used to generate
+them. If the given seed does not yield a prime q, a new random
+seed is chosen and placed at B<seed>.
+
+DSA_generate_parameters() places the iteration count in
+*B<counter_ret> and a counter used for finding a generator in
+*B<h_ret>, unless these are NULL.
+
+A callback function may be used to provide feedback about the progress
+of the key generation. If B<callback> is not B<NULL>, it will be
+called as follows:
+
+=over 4
+
+=item *
+
+When the the m-th candidate for q is generated, B<callback(0, m,
+cb_arg)> is called.
+
+=item *
+
+B<callback(1, j++, cb_arg)> is called in the inner loop of the
+Miller-Rabin primality test.
+
+=item *
+
+When a prime q has been found, B<callback(2, 0, cb_arg)> and
+B<callback(3, 0, cb_arg)> are called.
+
+=item *
+
+While candidates for p are being tested, B<callback(1, j++, cb_arg)>
+is called in the inner loop of the Miller-Rabin primality test, then
+B<callback(0, counter, cb_arg)> is called when the next candidate
+is chosen.
+
+=item *
+
+When p has been found, B<callback(2, 1, cb_arg)> is called.
+
+=item *
+
+When the generator has been found, B<callback(3, 1, cb_arg)> is called.
+
+=back
+
+=head1 RETURN VALUE
+
+DSA_generate_parameters() returns a pointer to the DSA structure, or
+NULL if the parameter generation fails. The error codes can be
+obtained by L<ERR_get_error(3)|ERR_get_error(3)>.
+
+=head1 BUGS
+
+The deterministic generation of p does not follow the NIST algorithm:
+r0 is SHA1(s+k+1), but should be SHA1(s+j+k) with j_0=2,
+j_counter=j_counter-1 + n + 1.
+
+Seed lengths E<gt> 20 are not supported.
+
+=head1 SEE ALSO
+
+L<dsa(3)|dsa(3)>, L<err(3)|err(3)>, L<rand(3)|rand(3)>,
+L<DSA_free(3)|DSA_free(3)>
+
+=head1 HISTORY
+
+DSA_generate_parameters() appeared in SSLeay 0.8. The B<cb_arg>
+argument was added in SSLeay 0.9.0.
+
+=cut