Document the DH library, and make some minor changes along the way.

1 files changed, 87 insertions, 0 deletions

diff --git a/doc/crypto/BN_generate_prime.pod b/doc/crypto/BN_generate_prime.pod
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+++ b/doc/crypto/BN_generate_prime.pod
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+=pod
+
+=head1 NAME
+
+BN_generate_prime, BN_is_prime - Generate primes and test for primality
+
+=head1 SYNOPSIS
+
+ #include <openssl/bn.h>
+
+ BIGNUM *BN_generate_prime(BIGNUM *ret, int num, int safe, BIGNUM *add,
+     BIGNUM *rem, void (*callback)(int, int, void *), void *cb_arg);
+
+ int BN_is_prime(BIGNUM *a, int checks, void (*callback)(int, int, 
+     void *), BN_CTX *ctx, void *cb_arg);
+
+=head1 DESCRIPTION
+
+BN_generate_prime() generates a pseudo-random prime number of B<num>
+bits.
+If B<ret> is not NULL, it will be used to store the number.
+
+If B<callback> is not B<NULL>, it is called as follows:
+
+=over 4
+
+=item *
+
+B<callback(0, i, cb_arg)> is called after generating the i-th
+potential prime number.
+
+=item *
+
+While the number is being tested for primality, B<callback(1, j,
+cb_arg)> is called as described below.
+
+=item *
+
+When a prime has been found, B<callback(2, i, cb_arg)> is called.
+
+=back
+
+The prime may have to fulfill additional requirements for use in
+Diffie-Hellman key exchange:
+
+If B<add> is not NULL, the prime will fulfill the condition p % B<add>
+== B<rem> (p % B<add> == 1 if B<rem> == NULL) in order to suit a given
+generator.
+
+If B<safe> is true, it will be a safe prime (i.e. a prime p so
+that (p-1)/2 is also prime).
+
+The PRNG must be seeded prior to calling BN_generate_prime().
+The prime number generation has a negligible error probability.
+
+BN_is_prime() tests if the number B<a> is prime. This is done by
+performing a Miller-Rabin probabilistic primality test with B<checks>
+iterations. If B<checks == BN_prime_check>, it uses the minimal number
+of iterations that yields a false positive rate of at most 2^-80 for
+random input.
+
+If B<callback> is not B<NULL>, B<callback(1, j, cb_arg)> is called
+after the j-th iteration. B<ctx> is a pre-allocated B<BN_CTX> (to save
+the overhead of allocating and freeing the structure in a loop), or
+NULL.
+
+=head1 RETURN VALUES
+
+BN_generate_prime() returns the prime number on success, NULL otherwise.
+
+BN_is_prime() returns 0 if the number is composite, 1 if it is
+prime with an error probability of less than 0.25^B<checks>, and
+-1 on error.
+
+The error codes can be obtained by ERR_get_error(3).
+
+=head1 SEE ALSO
+
+bn(3), err(3), rand(3)
+
+=head1 HISTORY
+
+The B<cb_arg> arguments to BN_generate_prime() and to BN_is_prime()
+were added in SSLeay 0.9.0. The B<ret> argument to BN_generate_prime()
+was added in SSLeay 0.9.1.
+
+=cut