/* crypto interfaces
 * Copyright (C) 1998, 1999  D. Hugh Redelmeier.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 * RCSID $Id: crypto.h,v 1.13 1999/12/13 00:40:50 dhr Exp $
 */

#include <gmp.h>    /* GNU MP library */

extern void init_crypto(void);

/* Oakley group descriptions */

extern MP_INT groupgenerator;	/* MODP group generator (2) */

struct oakley_group_desc {
    u_int16_t group;
    MP_INT *modulus;
    size_t bytes;
};

extern const struct oakley_group_desc unset_group;	/* magic signifier */
extern const struct oakley_group_desc *lookup_group(u_int16_t group);

/* unification of cryptographic encoding/decoding algorithms
 * The IV is taken from and returned to st->st_new_iv.
 * This allows the old IV to be retained.
 * Use update_iv to commit to the new IV (for example, once a packet has
 * been validated).
 */

#define MAX_OAKLEY_KEY_LEN  (3 * DES_CBC_BLOCK_SIZE)

struct state;	/* forward declaration, dammit */

struct encrypt_desc {
    size_t blocksize;
    size_t keysize;
    void (*crypt)(bool enc, void *buf, size_t buf_len, struct state *st);
};

const struct encrypt_desc oakley_encrypter[OAKLEY_CAST_CBC + 1];

#define update_iv(st)	memcpy((st)->st_iv, (st)->st_new_iv \
    , (st)->st_iv_len = (st)->st_new_iv_len)

/* unification of cryptographic hashing mechanisms */

union hash_ctx {
	MD5_CTX ctx_md5;
	SHA1_CTX ctx_sha1;
    };

struct hash_desc {
    size_t hash_digest_len; /* length of digest */
    void (*hash_init)(union hash_ctx *);	/* initialize context */
    void (*hash_update)(union hash_ctx *, const u_char *input, unsigned int len);   /* add input to hash */
    void (*hash_final)(u_char *output, union hash_ctx *);   /* finalize hash */
};

extern const struct hash_desc oakley_hasher[OAKLEY_TIGER+1];


/* HMAC package
 * Note that hmac_ctx can be (and is) copied since there are
 * no persistent pointers into it.
 */

struct hmac_ctx {
    const struct hash_desc *h;	/* underlying hash function */
    size_t hmac_digest_len;	/* copy of h->hash_digest_len */
    union hash_ctx hash_ctx;	/* ctx for hash function */
    u_char buf1[HMAC_BUFSIZE], buf2[HMAC_BUFSIZE];
    };

extern void hmac_init(
    struct hmac_ctx *ctx,
    const struct hash_desc *h,
    const u_char *key,
    size_t key_len);

#define hmac_init_chunk(ctx, h, ch) hmac_init((ctx), (h), (ch).ptr, (ch).len)

extern void hmac_reinit(struct hmac_ctx *ctx);	/* saves recreating pads */

extern void hmac_update(
    struct hmac_ctx *ctx,
    const u_char *data,
    size_t data_len);

#define hmac_update_chunk(ctx, ch) hmac_update((ctx), (ch).ptr, (ch).len)

extern void hmac_final(u_char *output, struct hmac_ctx *ctx);

#define hmac_final_chunk(ch, name, ctx) { \
	pfreeany((ch).ptr); \
	(ch).len = (ctx)->hmac_digest_len; \
	(ch).ptr = alloc_bytes((ch).len, name); \
	hmac_final((ch).ptr, (ctx)); \
    }