rijndael_decrypt
rijndael_decrypt(&c->r_ctx, cnow, plain);
void rijndael_decrypt(rijndael_ctx *, u_char *, u_char *);
void rijndael_decrypt(const rijndael_ctx *, const u_char *, u_char *);
rijndael_decrypt(&ctx->key, in, out);
rijndael_decrypt(&ctx->key, in, out);
rijndael_decrypt(&ctx->key1, block, out);