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

[openssl.git] / doc / crypto / dh.pod

diff --git a/doc/crypto/dh.pod b/doc/crypto/dh.pod
new file mode 100644 (file)
index 0000000..d364da4
--- /dev/null
+++ b/doc/crypto/dh.pod
@@ -0,0 +1,65 @@
+=pod
+
+=head1 NAME
+
+dh - Diffie-Hellman key agreement
+
+=head1 SYNOPSIS
+
+ #include <openssl/dh.h>
+
+ void DH_set_default_method(DH_METHOD *meth);
+ DH_METHOD *DH_get_default_method(void);
+ DH_METHOD *DH_set_method(DH *dh, DH_METHOD *meth);
+ DH *DH_new_method(DH_METHOD *meth);
+ DH_METHOD *DH_OpenSSL(void);
+
+ DH *  DH_new(void);
+ void  DH_free(DH *dh);
+
+ int   DH_size(DH *dh);
+
+ int DH_get_ex_new_index(long argl, char *argp, int (*new_func)(),
+            int (*dup_func)(), void (*free_func)());
+ int DH_set_ex_data(DH *d, int idx, char *arg);
+ char *DH_get_ex_data(DH *d, int idx);
+
+ DH *  DH_generate_parameters(int prime_len, int generator,
+               void (*callback)(int, int, void *), void *cb_arg);
+ int   DH_check(DH *dh, int *codes);
+
+ int   DH_generate_key(DH *dh);
+ int   DH_compute_key(unsigned char *key, BIGNUM *pub_key, DH *dh);
+
+ DH *  d2i_DHparams(DH **a, unsigned char **pp, long length);
+ int   i2d_DHparams(DH *a, unsigned char **pp);
+
+ int   DHparams_print_fp(FILE *fp, DH *x);
+ int   DHparams_print(BIO *bp, DH *x);
+
+=head1 DESCRIPTION
+
+These functions implement the Diffie-Hellman key agreement protocol.
+The generation of shared DH parameters is described in
+L<DH_generate_parameters(3)>; L<DH_generate_key(3)> describes how
+to perform a key agreement.
+
+The B<DH> structure consists of several BIGNUM components.
+
+ struct
+        {
+        BIGNUM *p;             // prime number (shared)
+        BIGNUM *g;             // generator of Z_p (shared)
+        BIGNUM *priv_key;      // private DH value x
+        BIGNUM *pub_key;       // public DH value g^x
+       // ...
+        };
+ DH
+
+=head1 SEE ALSO
+
+dh(1), bn(3), dsa(3), err(3), rand(3), rsa(3), DH_set_method(3),
+DH_new(3), DH_get_ex_new_index(3), DH_generate_parameters(3),
+DH_compute_key(3), d2i_DHparams(3), DHparams_print(3)
+
+=cut