doc/man3/EVP_EncryptInit.pod: add EVP_CIPHER_CTX_rand_key

 int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);

 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);

 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);

 int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key);

 const EVP_CIPHER *EVP_get_cipherbyname(const char *name);

 const EVP_CIPHER *EVP_get_cipherbynid(int nid);

EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined

and set.

EVP_CIPHER_CTX_rand_key() generates a random key of the appropriate length

based on the cipher context. The EVP_CIPHER can provide its own random key

generation routine to support keys of a specific form. B<Key> must point to a

buffer at least as big as the value returned by EVP_CIPHER_CTX_key_length().

=head1 RETURN VALUES

EVP_CIPHER_CTX_new() returns a pointer to a newly created

EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater

than zero for success and zero or a negative number.

EVP_CIPHER_CTX_rand_key() returns 1 for success.

=head1 CIPHER LISTING

All algorithms have a fixed key length unless otherwise stated.