/*

  silccipher.h

  Author: Pekka Riikonen <priikone@poseidon.pspt.fi>

  Copyright (C) 1997 - 2000 Pekka Riikonen

  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.
  
  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.

*/

#ifndef SILCCIPHER_H
#define SILCCIPHER_H

/* 
   SILC Cipher object.

   Default SILC cipher object to represent any cipher. The function
   pointers are the stub functions for each implemented cipher. Following
   short description of the fields:

   char *name

       Logical name of the cipher.

   unsigned int block_len

       Block size of the cipher.

   unsigned int key_len

       Length of the key of the cipher (in bits).

*/
typedef struct {
  char *name;
  unsigned int block_len;
  unsigned key_len;

  int (*set_key)(void *, const unsigned char *, unsigned int);
  int (*set_key_with_string)(void *, const unsigned char *, unsigned int);
  int (*encrypt)(void *, const unsigned char *, unsigned char *,
		 unsigned int, unsigned char *);
  int (*decrypt)(void *, const unsigned char *, unsigned char *, 
		 unsigned int, unsigned char *);
  unsigned int (*context_len)();
} SilcCipherObject;

#define SILC_CIPHER_MAX_IV_SIZE 16

/* The main SilcCipher structure. Use SilcCipher instead of SilcCipherStruct.
   Also remember that SilcCipher is a pointer. */
typedef struct SilcCipherStruct {
  SilcCipherObject *cipher;
  void *context;
  unsigned char iv[SILC_CIPHER_MAX_IV_SIZE];

  void (*set_iv)(struct SilcCipherStruct *, const unsigned char *);
  void (*get_iv)(struct SilcCipherStruct *, unsigned char *);
  unsigned int (*get_key_len)(struct SilcCipherStruct *, 
			      const unsigned char *);
  unsigned int (*get_block_len)(struct SilcCipherStruct *);
} *SilcCipher;

/* List of all registered ciphers. */
extern struct SilcCipherListStruct *silc_cipher_list;

/* Marks for all ciphers in silc. This can be used in silc_cipher_unregister
   to unregister all ciphers at once. */
#define SILC_ALL_CIPHERS ((SilcCipherObject *)1)

/* Macros */

/* Function names in SILC Crypto modules. The name of the cipher
   is appended into these names and used to the get correct symbol out
   of the module. All SILC Crypto API compliant modules must support
   these function names (use macros below to assure this). */
#define SILC_CIPHER_SIM_SET_KEY "set_key"
#define SILC_CIPHER_SIM_SET_KEY_WITH_STRING "set_key_with_string"
#define SILC_CIPHER_SIM_ENCRYPT_CBC "encrypt_cbc"
#define SILC_CIPHER_SIM_DECRYPT_CBC "decrypt_cbc"
#define SILC_CIPHER_SIM_CONTEXT_LEN "context_len"

/* These macros can be used to implement the SILC Crypto API and to avoid
   errors in the API these macros should be used always. */
#define SILC_CIPHER_API_SET_KEY(cipher)			\
int silc_##cipher##_set_key(void *context,		\
			    const unsigned char *key,	\
			    unsigned int keylen)
#define SILC_CIPHER_API_SET_KEY_WITH_STRING(cipher)			\
int silc_##cipher##_set_key_with_string(void *context,			\
					const unsigned char *string,	\
			 	        unsigned int stringlen)
#define SILC_CIPHER_API_ENCRYPT_CBC(cipher)			\
int silc_##cipher##_encrypt_cbc(void *context,			\
				const unsigned char *src,	\
		       	        unsigned char *dst,		\
				unsigned int len,		\
			        unsigned char *iv)
#define SILC_CIPHER_API_DECRYPT_CBC(cipher)			\
int silc_##cipher##_decrypt_cbc(void *context,			\
			      	const unsigned char *src,	\
				unsigned char *dst,		\
				unsigned int len,		\
				unsigned char *iv)
#define SILC_CIPHER_API_CONTEXT_LEN(cipher)			\
unsigned int silc_##cipher##_context_len()

/* Prototypes */
int silc_cipher_register(SilcCipherObject *cipher);
int silc_cipher_unregister(SilcCipherObject *cipher);
int silc_cipher_alloc(const unsigned char *name, SilcCipher *new_cipher);
void silc_cipher_free(SilcCipher cipher);
int silc_cipher_is_supported(const unsigned char *name);
char *silc_cipher_get_supported();
void silc_cipher_set_iv(SilcCipher itself, const unsigned char *iv);
void silc_cipher_get_iv(SilcCipher itself, unsigned char *iv);
unsigned int silc_cipher_get_key_len(SilcCipher itself, 
				     const unsigned char *name);
unsigned int silc_cipher_get_block_len(SilcCipher itself);

#endif