libpurple/cipher.c

/*
 * purple
 *
 * Purple is the legal property of its developers, whose names are too numerous
 * to list here.  Please refer to the COPYRIGHT file distributed with this
 * source distribution.
 *
 * Original des taken from gpg
 *
 * des.c - DES and Triple-DES encryption/decryption Algorithm
 *	Copyright (C) 1998 Free Software Foundation, Inc.
 *
 *	Please see below for more legal information!
 *
 *	 According to the definition of DES in FIPS PUB 46-2 from December 1993.
 *	 For a description of triple encryption, see:
 *	   Bruce Schneier: Applied Cryptography. Second Edition.
 *	   John Wiley & Sons, 1996. ISBN 0-471-12845-7. Pages 358 ff.
 *
 *	 This file is part of GnuPG.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02111-1301  USA
 */
#include "internal.h"
#include "cipher.h"
#include "dbus-maybe.h"
#include "debug.h"
#include "signals.h"
#include "value.h"

#if GLIB_CHECK_VERSION(2,16,0)
void
purple_g_checksum_init(PurpleCipherContext *context, GChecksumType type)
{
	GChecksum *checksum;

	checksum = g_checksum_new(type);
	purple_cipher_context_set_data(context, checksum);
}

void
purple_g_checksum_reset(PurpleCipherContext *context, GChecksumType type)
{
	GChecksum *checksum;

	checksum = purple_cipher_context_get_data(context);
	g_return_if_fail(checksum != NULL);

#if GLIB_CHECK_VERSION(2,18,0)
	g_checksum_reset(checksum);
#else
	g_checksum_free(checksum);
	checksum = g_checksum_new(type);
	purple_cipher_context_set_data(context, checksum);
#endif
}

void
purple_g_checksum_uninit(PurpleCipherContext *context)
{
	GChecksum *checksum;

	checksum = purple_cipher_context_get_data(context);
	g_return_if_fail(checksum != NULL);

	g_checksum_free(checksum);
}

void
purple_g_checksum_append(PurpleCipherContext *context, const guchar *data,
                         gsize len)
{
	GChecksum *checksum;

	checksum = purple_cipher_context_get_data(context);
	g_return_if_fail(checksum != NULL);

	while (len >= G_MAXSSIZE) {
		g_checksum_update(checksum, data, G_MAXSSIZE);
		len -= G_MAXSSIZE;
		data += G_MAXSSIZE;
	}

	if (len)
		g_checksum_update(checksum, data, len);
}

gboolean
purple_g_checksum_digest(PurpleCipherContext *context, GChecksumType type,
                         gsize len, guchar *digest, gsize *out_len)
{
	GChecksum *checksum;
	const gssize required_length = g_checksum_type_get_length(type);

	checksum = purple_cipher_context_get_data(context);

	g_return_val_if_fail(len >= required_length, FALSE);
	g_return_val_if_fail(checksum != NULL, FALSE);

	g_checksum_get_digest(checksum, digest, &len);

	purple_cipher_context_reset(context, NULL);

	if (out_len)
		*out_len = len;

	return TRUE;
}
#endif

/******************************************************************************
 * DES
 *****************************************************************************/

typedef struct _des_ctx
{
	guint32 encrypt_subkeys[32];
	guint32 decrypt_subkeys[32];
} des_ctx[1];

/*
 *  The s-box values are permuted according to the 'primitive function P'
 */
static const guint32 sbox1[64] =
{
	0x00808200, 0x00000000, 0x00008000, 0x00808202, 0x00808002, 0x00008202, 0x00000002, 0x00008000,
	0x00000200, 0x00808200, 0x00808202, 0x00000200, 0x00800202, 0x00808002, 0x00800000, 0x00000002,
	0x00000202, 0x00800200, 0x00800200, 0x00008200, 0x00008200, 0x00808000, 0x00808000, 0x00800202,
	0x00008002, 0x00800002, 0x00800002, 0x00008002, 0x00000000, 0x00000202, 0x00008202, 0x00800000,
	0x00008000, 0x00808202, 0x00000002, 0x00808000, 0x00808200, 0x00800000, 0x00800000, 0x00000200,
	0x00808002, 0x00008000, 0x00008200, 0x00800002, 0x00000200, 0x00000002, 0x00800202, 0x00008202,
	0x00808202, 0x00008002, 0x00808000, 0x00800202, 0x00800002, 0x00000202, 0x00008202, 0x00808200,
	0x00000202, 0x00800200, 0x00800200, 0x00000000, 0x00008002, 0x00008200, 0x00000000, 0x00808002
};

static const guint32 sbox2[64] =
{
	0x40084010, 0x40004000, 0x00004000, 0x00084010, 0x00080000, 0x00000010, 0x40080010, 0x40004010,
	0x40000010, 0x40084010, 0x40084000, 0x40000000, 0x40004000, 0x00080000, 0x00000010, 0x40080010,
	0x00084000, 0x00080010, 0x40004010, 0x00000000, 0x40000000, 0x00004000, 0x00084010, 0x40080000,
	0x00080010, 0x40000010, 0x00000000, 0x00084000, 0x00004010, 0x40084000, 0x40080000, 0x00004010,
	0x00000000, 0x00084010, 0x40080010, 0x00080000, 0x40004010, 0x40080000, 0x40084000, 0x00004000,
	0x40080000, 0x40004000, 0x00000010, 0x40084010, 0x00084010, 0x00000010, 0x00004000, 0x40000000,
	0x00004010, 0x40084000, 0x00080000, 0x40000010, 0x00080010, 0x40004010, 0x40000010, 0x00080010,
	0x00084000, 0x00000000, 0x40004000, 0x00004010, 0x40000000, 0x40080010, 0x40084010, 0x00084000
};

static const guint32 sbox3[64] =
{
	0x00000104, 0x04010100, 0x00000000, 0x04010004, 0x04000100, 0x00000000, 0x00010104, 0x04000100,
	0x00010004, 0x04000004, 0x04000004, 0x00010000, 0x04010104, 0x00010004, 0x04010000, 0x00000104,
	0x04000000, 0x00000004, 0x04010100, 0x00000100, 0x00010100, 0x04010000, 0x04010004, 0x00010104,
	0x04000104, 0x00010100, 0x00010000, 0x04000104, 0x00000004, 0x04010104, 0x00000100, 0x04000000,
	0x04010100, 0x04000000, 0x00010004, 0x00000104, 0x00010000, 0x04010100, 0x04000100, 0x00000000,
	0x00000100, 0x00010004, 0x04010104, 0x04000100, 0x04000004, 0x00000100, 0x00000000, 0x04010004,
	0x04000104, 0x00010000, 0x04000000, 0x04010104, 0x00000004, 0x00010104, 0x00010100, 0x04000004,
	0x04010000, 0x04000104, 0x00000104, 0x04010000, 0x00010104, 0x00000004, 0x04010004, 0x00010100
};

static const guint32 sbox4[64] =
{
	0x80401000, 0x80001040, 0x80001040, 0x00000040, 0x00401040, 0x80400040, 0x80400000, 0x80001000,
	0x00000000, 0x00401000, 0x00401000, 0x80401040, 0x80000040, 0x00000000, 0x00400040, 0x80400000,
	0x80000000, 0x00001000, 0x00400000, 0x80401000, 0x00000040, 0x00400000, 0x80001000, 0x00001040,
	0x80400040, 0x80000000, 0x00001040, 0x00400040, 0x00001000, 0x00401040, 0x80401040, 0x80000040,
	0x00400040, 0x80400000, 0x00401000, 0x80401040, 0x80000040, 0x00000000, 0x00000000, 0x00401000,
	0x00001040, 0x00400040, 0x80400040, 0x80000000, 0x80401000, 0x80001040, 0x80001040, 0x00000040,
	0x80401040, 0x80000040, 0x80000000, 0x00001000, 0x80400000, 0x80001000, 0x00401040, 0x80400040,
	0x80001000, 0x00001040, 0x00400000, 0x80401000, 0x00000040, 0x00400000, 0x00001000, 0x00401040
};

static const guint32 sbox5[64] =
{
	0x00000080, 0x01040080, 0x01040000, 0x21000080, 0x00040000, 0x00000080, 0x20000000, 0x01040000,
	0x20040080, 0x00040000, 0x01000080, 0x20040080, 0x21000080, 0x21040000, 0x00040080, 0x20000000,
	0x01000000, 0x20040000, 0x20040000, 0x00000000, 0x20000080, 0x21040080, 0x21040080, 0x01000080,
	0x21040000, 0x20000080, 0x00000000, 0x21000000, 0x01040080, 0x01000000, 0x21000000, 0x00040080,
	0x00040000, 0x21000080, 0x00000080, 0x01000000, 0x20000000, 0x01040000, 0x21000080, 0x20040080,
	0x01000080, 0x20000000, 0x21040000, 0x01040080, 0x20040080, 0x00000080, 0x01000000, 0x21040000,
	0x21040080, 0x00040080, 0x21000000, 0x21040080, 0x01040000, 0x00000000, 0x20040000, 0x21000000,
	0x00040080, 0x01000080, 0x20000080, 0x00040000, 0x00000000, 0x20040000, 0x01040080, 0x20000080
};

static const guint32 sbox6[64] =
{
	0x10000008, 0x10200000, 0x00002000, 0x10202008, 0x10200000, 0x00000008, 0x10202008, 0x00200000,
	0x10002000, 0x00202008, 0x00200000, 0x10000008, 0x00200008, 0x10002000, 0x10000000, 0x00002008,
	0x00000000, 0x00200008, 0x10002008, 0x00002000, 0x00202000, 0x10002008, 0x00000008, 0x10200008,
	0x10200008, 0x00000000, 0x00202008, 0x10202000, 0x00002008, 0x00202000, 0x10202000, 0x10000000,
	0x10002000, 0x00000008, 0x10200008, 0x00202000, 0x10202008, 0x00200000, 0x00002008, 0x10000008,
	0x00200000, 0x10002000, 0x10000000, 0x00002008, 0x10000008, 0x10202008, 0x00202000, 0x10200000,
	0x00202008, 0x10202000, 0x00000000, 0x10200008, 0x00000008, 0x00002000, 0x10200000, 0x00202008,
	0x00002000, 0x00200008, 0x10002008, 0x00000000, 0x10202000, 0x10000000, 0x00200008, 0x10002008
};

static const guint32 sbox7[64] =
{
	0x00100000, 0x02100001, 0x02000401, 0x00000000, 0x00000400, 0x02000401, 0x00100401, 0x02100400,
	0x02100401, 0x00100000, 0x00000000, 0x02000001, 0x00000001, 0x02000000, 0x02100001, 0x00000401,
	0x02000400, 0x00100401, 0x00100001, 0x02000400, 0x02000001, 0x02100000, 0x02100400, 0x00100001,
	0x02100000, 0x00000400, 0x00000401, 0x02100401, 0x00100400, 0x00000001, 0x02000000, 0x00100400,
	0x02000000, 0x00100400, 0x00100000, 0x02000401, 0x02000401, 0x02100001, 0x02100001, 0x00000001,
	0x00100001, 0x02000000, 0x02000400, 0x00100000, 0x02100400, 0x00000401, 0x00100401, 0x02100400,
	0x00000401, 0x02000001, 0x02100401, 0x02100000, 0x00100400, 0x00000000, 0x00000001, 0x02100401,
	0x00000000, 0x00100401, 0x02100000, 0x00000400, 0x02000001, 0x02000400, 0x00000400, 0x00100001
};

static const guint32 sbox8[64] =
{
	0x08000820, 0x00000800, 0x00020000, 0x08020820, 0x08000000, 0x08000820, 0x00000020, 0x08000000,
	0x00020020, 0x08020000, 0x08020820, 0x00020800, 0x08020800, 0x00020820, 0x00000800, 0x00000020,
	0x08020000, 0x08000020, 0x08000800, 0x00000820, 0x00020800, 0x00020020, 0x08020020, 0x08020800,
	0x00000820, 0x00000000, 0x00000000, 0x08020020, 0x08000020, 0x08000800, 0x00020820, 0x00020000,
	0x00020820, 0x00020000, 0x08020800, 0x00000800, 0x00000020, 0x08020020, 0x00000800, 0x00020820,
	0x08000800, 0x00000020, 0x08000020, 0x08020000, 0x08020020, 0x08000000, 0x00020000, 0x08000820,
	0x00000000, 0x08020820, 0x00020020, 0x08000020, 0x08020000, 0x08000800, 0x08000820, 0x00000000,
	0x08020820, 0x00020800, 0x00020800, 0x00000820, 0x00000820, 0x00020020, 0x08000000, 0x08020800
};


/*
 *  * These two tables are part of the 'permuted choice 1' function.
 *   * In this implementation several speed improvements are done.
 *    */
static const guint32 leftkey_swap[16] =
{
	0x00000000, 0x00000001, 0x00000100, 0x00000101,
	0x00010000, 0x00010001, 0x00010100, 0x00010101,
	0x01000000, 0x01000001, 0x01000100, 0x01000101,
	0x01010000, 0x01010001, 0x01010100, 0x01010101
};

static const guint32 rightkey_swap[16] =
{
	0x00000000, 0x01000000, 0x00010000, 0x01010000,
	0x00000100, 0x01000100, 0x00010100, 0x01010100,
	0x00000001, 0x01000001, 0x00010001, 0x01010001,
	0x00000101, 0x01000101, 0x00010101, 0x01010101,
};


/*
 *  Numbers of left shifts per round for encryption subkey schedule
 *  To calculate the decryption key scheduling we just reverse the
 *  ordering of the subkeys so we can omit the table for decryption
 *  subkey schedule.
 */
static const guint8 encrypt_rotate_tab[16] =
{
	1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1
};

/*
 *  Macro to swap bits across two words
 **/
#define DO_PERMUTATION(a, temp, b, offset, mask)	\
	temp = ((a>>offset) ^ b) & mask;			\
b ^= temp;						\
a ^= temp<<offset;


/*
 *  This performs the 'initial permutation' for the data to be encrypted or decrypted
 **/
#define INITIAL_PERMUTATION(left, temp, right)		\
	DO_PERMUTATION(left, temp, right, 4, 0x0f0f0f0f)	\
DO_PERMUTATION(left, temp, right, 16, 0x0000ffff)	\
DO_PERMUTATION(right, temp, left, 2, 0x33333333)	\
DO_PERMUTATION(right, temp, left, 8, 0x00ff00ff)	\
DO_PERMUTATION(left, temp, right, 1, 0x55555555)


/*
 * The 'inverse initial permutation'
 **/
#define FINAL_PERMUTATION(left, temp, right)		\
	DO_PERMUTATION(left, temp, right, 1, 0x55555555)	\
DO_PERMUTATION(right, temp, left, 8, 0x00ff00ff)	\
DO_PERMUTATION(right, temp, left, 2, 0x33333333)	\
DO_PERMUTATION(left, temp, right, 16, 0x0000ffff)	\
DO_PERMUTATION(left, temp, right, 4, 0x0f0f0f0f)


/*
 * A full DES round including 'expansion function', 'sbox substitution'
 * and 'primitive function P' but without swapping the left and right word.
 **/
#define DES_ROUND(from, to, work, subkey)		\
	work = ((from<<1) | (from>>31)) ^ *subkey++;	\
to ^= sbox8[  work	    & 0x3f ];			\
to ^= sbox6[ (work>>8)  & 0x3f ];			\
to ^= sbox4[ (work>>16) & 0x3f ];			\
to ^= sbox2[ (work>>24) & 0x3f ];			\
work = ((from>>3) | (from<<29)) ^ *subkey++;	\
to ^= sbox7[  work	    & 0x3f ];			\
to ^= sbox5[ (work>>8)  & 0x3f ];			\
to ^= sbox3[ (work>>16) & 0x3f ];			\
to ^= sbox1[ (work>>24) & 0x3f ];


/*
 * Macros to convert 8 bytes from/to 32bit words
 **/
#define READ_64BIT_DATA(data, left, right)					\
	left  = (data[0] << 24) | (data[1] << 16) | (data[2] << 8) | data[3];	\
right = (data[4] << 24) | (data[5] << 16) | (data[6] << 8) | data[7];

#define WRITE_64BIT_DATA(data, left, right)					\
	data[0] = (left >> 24) &0xff; data[1] = (left >> 16) &0xff; 		\
data[2] = (left >> 8) &0xff; data[3] = left &0xff;				\
data[4] = (right >> 24) &0xff; data[5] = (right >> 16) &0xff;		\
data[6] = (right >> 8) &0xff; data[7] = right &0xff;


/*
 * des_key_schedule():	  Calculate 16 subkeys pairs (even/odd) for
 *			  16 encryption rounds.
 *			  To calculate subkeys for decryption the caller
 *    			  have to reorder the generated subkeys.
 *
 *        rawkey:	    8 Bytes of key data
 *        subkey:	    Array of at least 32 guint32s. Will be filled
 *    		    with calculated subkeys.
 *
 **/
static void
des_key_schedule (const guint8 * rawkey, guint32 * subkey)
{
	guint32 left, right, work;
	int round;

	READ_64BIT_DATA (rawkey, left, right)

		DO_PERMUTATION (right, work, left, 4, 0x0f0f0f0f)
		DO_PERMUTATION (right, work, left, 0, 0x10101010)

		left = (leftkey_swap[(left >> 0) & 0xf] << 3) | (leftkey_swap[(left >> 8) & 0xf] << 2)
		| (leftkey_swap[(left >> 16) & 0xf] << 1) | (leftkey_swap[(left >> 24) & 0xf])
		| (leftkey_swap[(left >> 5) & 0xf] << 7) | (leftkey_swap[(left >> 13) & 0xf] << 6)
		| (leftkey_swap[(left >> 21) & 0xf] << 5) | (leftkey_swap[(left >> 29) & 0xf] << 4);

	left &= 0x0fffffff;

	right = (rightkey_swap[(right >> 1) & 0xf] << 3) | (rightkey_swap[(right >> 9) & 0xf] << 2)
		| (rightkey_swap[(right >> 17) & 0xf] << 1) | (rightkey_swap[(right >> 25) & 0xf])
		| (rightkey_swap[(right >> 4) & 0xf] << 7) | (rightkey_swap[(right >> 12) & 0xf] << 6)
		| (rightkey_swap[(right >> 20) & 0xf] << 5) | (rightkey_swap[(right >> 28) & 0xf] << 4);

	right &= 0x0fffffff;

	for (round = 0; round < 16; ++round)
	{
		left = ((left << encrypt_rotate_tab[round]) | (left >> (28 - encrypt_rotate_tab[round]))) & 0x0fffffff;
		right = ((right << encrypt_rotate_tab[round]) | (right >> (28 - encrypt_rotate_tab[round]))) & 0x0fffffff;

		*subkey++ = ((left << 4) & 0x24000000)
			| ((left << 28) & 0x10000000)
			| ((left << 14) & 0x08000000)
			| ((left << 18) & 0x02080000)
			| ((left << 6) & 0x01000000)
			| ((left << 9) & 0x00200000)
			| ((left >> 1) & 0x00100000)
			| ((left << 10) & 0x00040000)
			| ((left << 2) & 0x00020000)
			| ((left >> 10) & 0x00010000)
			| ((right >> 13) & 0x00002000)
			| ((right >> 4) & 0x00001000)
			| ((right << 6) & 0x00000800)
			| ((right >> 1) & 0x00000400)
			| ((right >> 14) & 0x00000200)
			| (right & 0x00000100)
			| ((right >> 5) & 0x00000020)
			| ((right >> 10) & 0x00000010)
			| ((right >> 3) & 0x00000008)
			| ((right >> 18) & 0x00000004)
			| ((right >> 26) & 0x00000002)
			| ((right >> 24) & 0x00000001);

		*subkey++ = ((left << 15) & 0x20000000)
			| ((left << 17) & 0x10000000)
			| ((left << 10) & 0x08000000)
			| ((left << 22) & 0x04000000)
			| ((left >> 2) & 0x02000000)
			| ((left << 1) & 0x01000000)
			| ((left << 16) & 0x00200000)
			| ((left << 11) & 0x00100000)
			| ((left << 3) & 0x00080000)
			| ((left >> 6) & 0x00040000)
			| ((left << 15) & 0x00020000)
			| ((left >> 4) & 0x00010000)
			| ((right >> 2) & 0x00002000)
			| ((right << 8) & 0x00001000)
			| ((right >> 14) & 0x00000808)
			| ((right >> 9) & 0x00000400)
			| ((right) & 0x00000200)
			| ((right << 7) & 0x00000100)
			| ((right >> 7) & 0x00000020)
			| ((right >> 3) & 0x00000011)
			| ((right << 2) & 0x00000004)
			| ((right >> 21) & 0x00000002);
	}
}


/*
 *  Fill a DES context with subkeys calculated from a 64bit key.
 *  Does not check parity bits, but simply ignore them.
 *  Does not check for weak keys.
 **/
static void
des_set_key (PurpleCipherContext *context, const guchar * key)
{
	struct _des_ctx *ctx = purple_cipher_context_get_data(context);
	int i;

	des_key_schedule (key, ctx->encrypt_subkeys);

	for(i=0; i<32; i+=2)
	{
		ctx->decrypt_subkeys[i]	= ctx->encrypt_subkeys[30-i];
		ctx->decrypt_subkeys[i+1] = ctx->encrypt_subkeys[31-i];
	}
}


/*
 *  Electronic Codebook Mode DES encryption/decryption of data according
 *  to 'mode'.
 **/
static int
des_ecb_crypt (struct _des_ctx *ctx, const guint8 * from, guint8 * to, int mode)
{
	guint32 left, right, work;
	guint32 *keys;

	keys = mode ? ctx->decrypt_subkeys : ctx->encrypt_subkeys;

	READ_64BIT_DATA (from, left, right)
		INITIAL_PERMUTATION (left, work, right)

		DES_ROUND (right, left, work, keys) DES_ROUND (left, right, work, keys)
		DES_ROUND (right, left, work, keys) DES_ROUND (left, right, work, keys)
		DES_ROUND (right, left, work, keys) DES_ROUND (left, right, work, keys)
		DES_ROUND (right, left, work, keys) DES_ROUND (left, right, work, keys)
		DES_ROUND (right, left, work, keys) DES_ROUND (left, right, work, keys)
		DES_ROUND (right, left, work, keys) DES_ROUND (left, right, work, keys)
		DES_ROUND (right, left, work, keys) DES_ROUND (left, right, work, keys)
		DES_ROUND (right, left, work, keys) DES_ROUND (left, right, work, keys)

		FINAL_PERMUTATION (right, work, left)
		WRITE_64BIT_DATA (to, right, left)

		return 0;
}

static gint
des_encrypt(PurpleCipherContext *context, const guchar data[],
	    size_t len, guchar output[], size_t *outlen) {
	int offset = 0;
	int i = 0;
	int tmp;
	guint8 buf[8] = {0,0,0,0,0,0,0,0};
	while(offset+8<=len) {
		des_ecb_crypt(purple_cipher_context_get_data(context),
				data+offset,
				output+offset,
				0);
		offset+=8;
	}
	*outlen = len;
	if(offset<len) {
		*outlen += len - offset;
		tmp = offset;
		while(tmp<len) {
			buf[i++] = data[tmp];
			tmp++;
		}
		des_ecb_crypt(purple_cipher_context_get_data(context),
				buf,
				output+offset,
				0);
	}
	return 0;
}

static gint
des_decrypt(PurpleCipherContext *context, const guchar data[],
	    size_t len, guchar output[], size_t *outlen) {
	int offset = 0;
	int i = 0;
	int tmp;
	guint8 buf[8] = {0,0,0,0,0,0,0,0};
	while(offset+8<=len) {
		des_ecb_crypt(purple_cipher_context_get_data(context),
				data+offset,
				output+offset,
				1);
		offset+=8;
	}
	*outlen = len;
	if(offset<len) {
		*outlen += len - offset;
		tmp = offset;
		while(tmp<len) {
			buf[i++] = data[tmp];
			tmp++;
		}
		des_ecb_crypt(purple_cipher_context_get_data(context),
				buf,
				output+offset,
				1);
	}
	return 0;
}

static void
des_init(PurpleCipherContext *context, gpointer extra) {
	struct _des_ctx *mctx;
	mctx = g_new0(struct _des_ctx, 1);
	purple_cipher_context_set_data(context, mctx);
}

static void
des_uninit(PurpleCipherContext *context) {
	struct _des_ctx *des_context;

	des_context = purple_cipher_context_get_data(context);
	memset(des_context, 0, sizeof(*des_context));

	g_free(des_context);
	des_context = NULL;
}

static PurpleCipherOps DESOps = {
	NULL,              /* Set option */
	NULL,              /* Get option */
	des_init,          /* init */
 	NULL,              /* reset */
	des_uninit,        /* uninit */
	NULL,              /* set iv */
	NULL,              /* append */
	NULL,              /* digest */
	des_encrypt,       /* encrypt */
	des_decrypt,       /* decrypt */
	NULL,              /* set salt */
	NULL,              /* get salt size */
	des_set_key,       /* set key */
	NULL,              /* get key size */
	NULL,              /* set batch mode */
	NULL,              /* get batch mode */
	NULL,              /* get block size */
	NULL               /* set key with len */
};

/******************************************************************************
 * Triple-DES
 *****************************************************************************/

typedef struct _des3_ctx
{
	PurpleCipherBatchMode mode;
	guchar iv[8];
	/* First key for encryption */
	struct _des_ctx key1;
	/* Second key for decryption */
	struct _des_ctx key2;
	/* Third key for encryption */
	struct _des_ctx key3;
} des3_ctx[1];

/*
 *  Fill a DES3 context with subkeys calculated from 3 64bit key.
 *  Does not check parity bits, but simply ignore them.
 *  Does not check for weak keys.
 **/
static void
des3_set_key(PurpleCipherContext *context, const guchar * key)
{
	struct _des3_ctx *ctx = purple_cipher_context_get_data(context);
	int i;

	des_key_schedule (key +  0, ctx->key1.encrypt_subkeys);
	des_key_schedule (key +  8, ctx->key2.encrypt_subkeys);
	des_key_schedule (key + 16, ctx->key3.encrypt_subkeys);

	for (i = 0; i < 32; i += 2)
	{
		ctx->key1.decrypt_subkeys[i]	= ctx->key1.encrypt_subkeys[30-i];
		ctx->key1.decrypt_subkeys[i+1]	= ctx->key1.encrypt_subkeys[31-i];
		ctx->key2.decrypt_subkeys[i]	= ctx->key2.encrypt_subkeys[30-i];
		ctx->key2.decrypt_subkeys[i+1]	= ctx->key2.encrypt_subkeys[31-i];
		ctx->key3.decrypt_subkeys[i]	= ctx->key3.encrypt_subkeys[30-i];
		ctx->key3.decrypt_subkeys[i+1]	= ctx->key3.encrypt_subkeys[31-i];
	}
}

static gint
des3_ecb_encrypt(struct _des3_ctx *ctx, const guchar data[],
                 size_t len, guchar output[], size_t *outlen)
{
	int offset = 0;
	int i = 0;
	int tmp;
	guint8 buf[8] = {0,0,0,0,0,0,0,0};
	while (offset + 8 <= len) {
		des_ecb_crypt(&ctx->key1,
		              data+offset,
		              output+offset,
		              0);
		des_ecb_crypt(&ctx->key2,
		              output+offset,
		              buf,
		              1);
		des_ecb_crypt(&ctx->key3,
		              buf,
		              output+offset,
		              0);
		offset += 8;
	}
	*outlen = len;
	if (offset < len) {
		*outlen += len - offset;
		tmp = offset;
		memset(buf, 0, 8);
		while (tmp < len) {
			buf[i++] = data[tmp];
			tmp++;
		}
		des_ecb_crypt(&ctx->key1,
		              buf,
		              output+offset,
		              0);
		des_ecb_crypt(&ctx->key2,
		              output+offset,
		              buf,
		              1);
		des_ecb_crypt(&ctx->key3,
		              buf,
		              output+offset,
		              0);
	}
	return 0;
}

static gint
des3_cbc_encrypt(struct _des3_ctx *ctx, const guchar data[],
                 size_t len, guchar output[], size_t *outlen)
{
	int offset = 0;
	int i = 0;
	int tmp;
	guint8 buf[8];
	memcpy(buf, ctx->iv, 8);
	while (offset + 8 <= len) {
		for (i = 0; i < 8; i++)
			buf[i] ^= data[offset + i];
		des_ecb_crypt(&ctx->key1,
		              buf,
		              output+offset,
		              0);
		des_ecb_crypt(&ctx->key2,
		              output+offset,
		              buf,
		              1);
		des_ecb_crypt(&ctx->key3,
		              buf,
		              output+offset,
		              0);
		memcpy(buf, output+offset, 8);
		offset += 8;
	}
	*outlen = len;
	if (offset < len) {
		*outlen += len - offset;
		tmp = offset;
		i = 0;
		while (tmp < len) {
			buf[i++] ^= data[tmp];
			tmp++;
		}
		des_ecb_crypt(&ctx->key1,
		              buf,
		              output+offset,
		              0);
		des_ecb_crypt(&ctx->key2,
		              output+offset,
		              buf,
		              1);
		des_ecb_crypt(&ctx->key3,
		              buf,
		              output+offset,
		              0);
	}
	return 0;
}

static gint
des3_encrypt(PurpleCipherContext *context, const guchar data[],
             size_t len, guchar output[], size_t *outlen)
{
	struct _des3_ctx *ctx = purple_cipher_context_get_data(context);

	if (ctx->mode == PURPLE_CIPHER_BATCH_MODE_ECB) {
		return des3_ecb_encrypt(ctx, data, len, output, outlen);
	} else if (ctx->mode == PURPLE_CIPHER_BATCH_MODE_CBC) {
		return des3_cbc_encrypt(ctx, data, len, output, outlen);
	} else {
		g_return_val_if_reached(0);
	}

	return 0;
}

static gint
des3_ecb_decrypt(struct _des3_ctx *ctx, const guchar data[],
                 size_t len, guchar output[], size_t *outlen)
{
	int offset = 0;
	int i = 0;
	int tmp;
	guint8 buf[8] = {0,0,0,0,0,0,0,0};
	while (offset + 8 <= len) {
		/* NOTE: Apply key in reverse */
		des_ecb_crypt(&ctx->key3,
		              data+offset,
		              output+offset,
		              1);
		des_ecb_crypt(&ctx->key2,
		              output+offset,
		              buf,
		              0);
		des_ecb_crypt(&ctx->key1,
		              buf,
		              output+offset,
		              1);
		offset+=8;
	}
	*outlen = len;
	if (offset < len) {
		*outlen += len - offset;
		tmp = offset;
		memset(buf, 0, 8);
		while (tmp < len) {
			buf[i++] = data[tmp];
			tmp++;
		}
		des_ecb_crypt(&ctx->key3,
		              buf,
		              output+offset,
		              1);
		des_ecb_crypt(&ctx->key2,
		              output+offset,
		              buf,
		              0);
		des_ecb_crypt(&ctx->key1,
		              buf,
		              output+offset,
		              1);
	}
	return 0;
}

static gint
des3_cbc_decrypt(struct _des3_ctx *ctx, const guchar data[],
                 size_t len, guchar output[], size_t *outlen)
{
	int offset = 0;
	int i = 0;
	int tmp;
	guint8 buf[8] = {0,0,0,0,0,0,0,0};
	guint8 link[8];
	memcpy(link, ctx->iv, 8);
	while (offset + 8 <= len) {
		des_ecb_crypt(&ctx->key3,
		              data+offset,
		              output+offset,
		              1);
		des_ecb_crypt(&ctx->key2,
		              output+offset,
		              buf,
		              0);
		des_ecb_crypt(&ctx->key1,
		              buf,
		              output+offset,
		              1);
		for (i = 0; i < 8; i++)
			output[offset + i] ^= link[i];
		memcpy(link, data + offset, 8);
		offset+=8;
	}
	*outlen = len;
	if(offset<len) {
		*outlen += len - offset;
		tmp = offset;
		memset(buf, 0, 8);
		i = 0;
		while(tmp<len) {
			buf[i++] = data[tmp];
			tmp++;
		}
		des_ecb_crypt(&ctx->key3,
		              buf,
		              output+offset,
		              1);
		des_ecb_crypt(&ctx->key2,
		              output+offset,
		              buf,
		              0);
		des_ecb_crypt(&ctx->key1,
		              buf,
		              output+offset,
		              1);
		for (i = 0; i < 8; i++)
			output[offset + i] ^= link[i];
	}
	return 0;
}

static gint
des3_decrypt(PurpleCipherContext *context, const guchar data[],
             size_t len, guchar output[], size_t *outlen)
{
	struct _des3_ctx *ctx = purple_cipher_context_get_data(context);

	if (ctx->mode == PURPLE_CIPHER_BATCH_MODE_ECB) {
		return des3_ecb_decrypt(ctx, data, len, output, outlen);
	} else if (ctx->mode == PURPLE_CIPHER_BATCH_MODE_CBC) {
		return des3_cbc_decrypt(ctx, data, len, output, outlen);
	} else {
		g_return_val_if_reached(0);
	}

	return 0;
}

static void
des3_set_batch(PurpleCipherContext *context, PurpleCipherBatchMode mode)
{
	struct _des3_ctx *ctx = purple_cipher_context_get_data(context);

	ctx->mode = mode;
}

static PurpleCipherBatchMode
des3_get_batch(PurpleCipherContext *context)
{
	struct _des3_ctx *ctx = purple_cipher_context_get_data(context);

	return ctx->mode;
}

static void
des3_set_iv(PurpleCipherContext *context, guchar *iv, size_t len)
{
	struct _des3_ctx *ctx;

	g_return_if_fail(len == 8);

	ctx = purple_cipher_context_get_data(context);

	memcpy(ctx->iv, iv, len);
}

static void
des3_init(PurpleCipherContext *context, gpointer extra)
{
	struct _des3_ctx *mctx;
	mctx = g_new0(struct _des3_ctx, 1);
	purple_cipher_context_set_data(context, mctx);
}

static void
des3_uninit(PurpleCipherContext *context)
{
	struct _des3_ctx *des3_context;

	des3_context = purple_cipher_context_get_data(context);
	memset(des3_context, 0, sizeof(*des3_context));

	g_free(des3_context);
	des3_context = NULL;
}

static PurpleCipherOps DES3Ops = {
	NULL,              /* Set option */
	NULL,              /* Get option */
	des3_init,         /* init */
	NULL,              /* reset */
	des3_uninit,       /* uninit */
	des3_set_iv,       /* set iv */
	NULL,              /* append */
	NULL,              /* digest */
	des3_encrypt,      /* encrypt */
	des3_decrypt,      /* decrypt */
	NULL,              /* set salt */
	NULL,              /* get salt size */
	des3_set_key,      /* set key */
	NULL,              /* get key size */
	des3_set_batch,    /* set batch mode */
	des3_get_batch,    /* get batch mode */
	NULL,              /* get block size */
	NULL               /* set key with len */
};

/*******************************************************************************
 * Structs
 ******************************************************************************/
struct _PurpleCipher {
	gchar *name;          /**< Internal name - used for searching */
	PurpleCipherOps *ops; /**< Operations supported by this cipher */
	guint ref;            /**< Reference count */
};

struct _PurpleCipherContext {
	PurpleCipher *cipher; /**< Cipher this context is under */
	gpointer data;        /**< Internal cipher state data */
};

/******************************************************************************
 * Globals
 *****************************************************************************/
static GList *ciphers = NULL;

/******************************************************************************
 * PurpleCipher API
 *****************************************************************************/
const gchar *
purple_cipher_get_name(PurpleCipher *cipher) {
	g_return_val_if_fail(cipher, NULL);

	return cipher->name;
}

guint
purple_cipher_get_capabilities(PurpleCipher *cipher) {
	PurpleCipherOps *ops = NULL;
	guint caps = 0;

	g_return_val_if_fail(cipher, 0);

	ops = cipher->ops;
	g_return_val_if_fail(ops, 0);

	if(ops->set_option)
		caps |= PURPLE_CIPHER_CAPS_SET_OPT;
	if(ops->get_option)
		caps |= PURPLE_CIPHER_CAPS_GET_OPT;
	if(ops->init)
		caps |= PURPLE_CIPHER_CAPS_INIT;
	if(ops->reset)
		caps |= PURPLE_CIPHER_CAPS_RESET;
	if(ops->uninit)
		caps |= PURPLE_CIPHER_CAPS_UNINIT;
	if(ops->set_iv)
		caps |= PURPLE_CIPHER_CAPS_SET_IV;
	if(ops->append)
		caps |= PURPLE_CIPHER_CAPS_APPEND;
	if(ops->digest)
		caps |= PURPLE_CIPHER_CAPS_DIGEST;
	if(ops->encrypt)
		caps |= PURPLE_CIPHER_CAPS_ENCRYPT;
	if(ops->decrypt)
		caps |= PURPLE_CIPHER_CAPS_DECRYPT;
	if(ops->set_salt)
		caps |= PURPLE_CIPHER_CAPS_SET_SALT;
	if(ops->get_salt_size)
		caps |= PURPLE_CIPHER_CAPS_GET_SALT_SIZE;
	if(ops->set_key)
		caps |= PURPLE_CIPHER_CAPS_SET_KEY;
	if(ops->get_key_size)
		caps |= PURPLE_CIPHER_CAPS_GET_KEY_SIZE;
	if(ops->set_batch_mode)
		caps |= PURPLE_CIPHER_CAPS_SET_BATCH_MODE;
	if(ops->get_batch_mode)
		caps |= PURPLE_CIPHER_CAPS_GET_BATCH_MODE;
	if(ops->get_block_size)
		caps |= PURPLE_CIPHER_CAPS_GET_BLOCK_SIZE;
	if(ops->set_key_with_len)
		caps |= PURPLE_CIPHER_CAPS_SET_KEY_WITH_LEN;

	return caps;
}

gboolean
purple_cipher_digest_region(const gchar *name, const guchar *data,
						  size_t data_len, size_t in_len,
						  guchar digest[], size_t *out_len)
{
	PurpleCipher *cipher;
	PurpleCipherContext *context;
	gboolean ret = FALSE;

	g_return_val_if_fail(name, FALSE);
	g_return_val_if_fail(data, FALSE);

	cipher = purple_ciphers_find_cipher(name);

	g_return_val_if_fail(cipher, FALSE);

	if(!cipher->ops->append || !cipher->ops->digest) {
		purple_debug_warning("cipher", "purple_cipher_region failed: "
						"the %s cipher does not support appending and or "
						"digesting.", cipher->name);
		return FALSE;
	}

	context = purple_cipher_context_new(cipher, NULL);
	purple_cipher_context_append(context, data, data_len);
	ret = purple_cipher_context_digest(context, in_len, digest, out_len);
	purple_cipher_context_destroy(context);

	return ret;
}

/******************************************************************************
 * PurpleCiphers API
 *****************************************************************************/
PurpleCipher *
purple_ciphers_find_cipher(const gchar *name) {
	PurpleCipher *cipher;
	GList *l;

	g_return_val_if_fail(name, NULL);

	for(l = ciphers; l; l = l->next) {
		cipher = PURPLE_CIPHER(l->data);

		if(!g_ascii_strcasecmp(cipher->name, name))
			return cipher;
	}

	return NULL;
}

PurpleCipher *
purple_ciphers_register_cipher(const gchar *name, PurpleCipherOps *ops) {
	PurpleCipher *cipher = NULL;

	g_return_val_if_fail(name, NULL);
	g_return_val_if_fail(ops, NULL);
	g_return_val_if_fail(!purple_ciphers_find_cipher(name), NULL);

	cipher = g_new0(PurpleCipher, 1);
	PURPLE_DBUS_REGISTER_POINTER(cipher, PurpleCipher);

	cipher->name = g_strdup(name);
	cipher->ops = ops;

	ciphers = g_list_append(ciphers, cipher);

	purple_signal_emit(purple_ciphers_get_handle(), "cipher-added", cipher);

	return cipher;
}

gboolean
purple_ciphers_unregister_cipher(PurpleCipher *cipher) {
	g_return_val_if_fail(cipher, FALSE);
	g_return_val_if_fail(cipher->ref == 0, FALSE);

	purple_signal_emit(purple_ciphers_get_handle(), "cipher-removed", cipher);

	ciphers = g_list_remove(ciphers, cipher);

	g_free(cipher->name);

	PURPLE_DBUS_UNREGISTER_POINTER(cipher);
	g_free(cipher);

	return TRUE;
}

GList *
purple_ciphers_get_ciphers() {
	return ciphers;
}

/******************************************************************************
 * PurpleCipher Subsystem API
 *****************************************************************************/
gpointer
purple_ciphers_get_handle() {
	static gint handle;

	return &handle;
}

/* This are implemented in the purple-ciphers sublibrary built in the ciphers
 * directory.  We could put a header file in there, but it's less hassle for
 * the developer to just add it here since they have to register it here as
 * well.
 */
PurpleCipherOps *purple_hmac_cipher_get_ops();
PurpleCipherOps *purple_md4_cipher_get_ops();
PurpleCipherOps *purple_md5_cipher_get_ops();
PurpleCipherOps *purple_rc4_cipher_get_ops();
PurpleCipherOps *purple_sha1_cipher_get_ops();
PurpleCipherOps *purple_sha256_cipher_get_ops();

void
purple_ciphers_init() {
	gpointer handle;

	handle = purple_ciphers_get_handle();

	purple_signal_register(handle, "cipher-added",
						 purple_marshal_VOID__POINTER, NULL, 1,
						 purple_value_new(PURPLE_TYPE_SUBTYPE,
										PURPLE_SUBTYPE_CIPHER));
	purple_signal_register(handle, "cipher-removed",
						 purple_marshal_VOID__POINTER, NULL, 1,
						 purple_value_new(PURPLE_TYPE_SUBTYPE,
										PURPLE_SUBTYPE_CIPHER));

	purple_ciphers_register_cipher("md5", purple_md5_cipher_get_ops());
	purple_ciphers_register_cipher("sha1", purple_sha1_cipher_get_ops());
	purple_ciphers_register_cipher("sha256", purple_sha256_cipher_get_ops());
	purple_ciphers_register_cipher("md4", purple_md4_cipher_get_ops());
	purple_ciphers_register_cipher("hmac", purple_hmac_cipher_get_ops());
	purple_ciphers_register_cipher("des", &DESOps);
	purple_ciphers_register_cipher("des3", &DES3Ops);
	purple_ciphers_register_cipher("rc4", purple_rc4_cipher_get_ops());
}

void
purple_ciphers_uninit() {
	PurpleCipher *cipher;
	GList *l, *ll;

	for(l = ciphers; l; l = ll) {
		ll = l->next;

		cipher = PURPLE_CIPHER(l->data);
		purple_ciphers_unregister_cipher(cipher);
	}

	g_list_free(ciphers);

	purple_signals_unregister_by_instance(purple_ciphers_get_handle());
}

/******************************************************************************
 * PurpleCipherContext API
 *****************************************************************************/
void
purple_cipher_context_set_option(PurpleCipherContext *context, const gchar *name,
							   gpointer value)
{
	PurpleCipher *cipher = NULL;

	g_return_if_fail(context);
	g_return_if_fail(name);

	cipher = context->cipher;
	g_return_if_fail(cipher);

	if(cipher->ops && cipher->ops->set_option)
		cipher->ops->set_option(context, name, value);
	else
		purple_debug_warning("cipher", "the %s cipher does not support the "
						"set_option operation\n", cipher->name);
}

gpointer
purple_cipher_context_get_option(PurpleCipherContext *context, const gchar *name) {
	PurpleCipher *cipher = NULL;

	g_return_val_if_fail(context, NULL);
	g_return_val_if_fail(name, NULL);

	cipher = context->cipher;
	g_return_val_if_fail(cipher, NULL);

	if(cipher->ops && cipher->ops->get_option)
		return cipher->ops->get_option(context, name);
	else {
		purple_debug_warning("cipher", "the %s cipher does not support the "
						"get_option operation\n", cipher->name);

		return NULL;
	}
}

PurpleCipherContext *
purple_cipher_context_new(PurpleCipher *cipher, void *extra) {
	PurpleCipherContext *context = NULL;

	g_return_val_if_fail(cipher, NULL);

	cipher->ref++;

	context = g_new0(PurpleCipherContext, 1);
	context->cipher = cipher;

	if(cipher->ops->init)
		cipher->ops->init(context, extra);

	return context;
}

PurpleCipherContext *
purple_cipher_context_new_by_name(const gchar *name, void *extra) {
	PurpleCipher *cipher;

	g_return_val_if_fail(name, NULL);

	cipher = purple_ciphers_find_cipher(name);

	g_return_val_if_fail(cipher, NULL);

	return purple_cipher_context_new(cipher, extra);
}

void
purple_cipher_context_reset(PurpleCipherContext *context, void *extra) {
	PurpleCipher *cipher = NULL;

	g_return_if_fail(context);

	cipher = context->cipher;
	g_return_if_fail(cipher);

	if(cipher->ops && cipher->ops->reset)
		context->cipher->ops->reset(context, extra);
}

void
purple_cipher_context_destroy(PurpleCipherContext *context) {
	PurpleCipher *cipher = NULL;

	g_return_if_fail(context);

	cipher = context->cipher;
	g_return_if_fail(cipher);

	cipher->ref--;

	if(cipher->ops && cipher->ops->uninit)
		cipher->ops->uninit(context);

	memset(context, 0, sizeof(*context));
	g_free(context);
	context = NULL;
}

void
purple_cipher_context_set_iv(PurpleCipherContext *context, guchar *iv, size_t len)
{
	PurpleCipher *cipher = NULL;

	g_return_if_fail(context);
	g_return_if_fail(iv);

	cipher = context->cipher;
	g_return_if_fail(cipher);

	if(cipher->ops && cipher->ops->set_iv)
		cipher->ops->set_iv(context, iv, len);
	else
		purple_debug_warning("cipher", "the %s cipher does not support the set"
						"initialization vector operation\n", cipher->name);
}

void
purple_cipher_context_append(PurpleCipherContext *context, const guchar *data,
								size_t len)
{
	PurpleCipher *cipher = NULL;

	g_return_if_fail(context);

	cipher = context->cipher;
	g_return_if_fail(cipher);

	if(cipher->ops && cipher->ops->append)
		cipher->ops->append(context, data, len);
	else
		purple_debug_warning("cipher", "the %s cipher does not support the append "
						"operation\n", cipher->name);
}

gboolean
purple_cipher_context_digest(PurpleCipherContext *context, size_t in_len,
						   guchar digest[], size_t *out_len)
{
	PurpleCipher *cipher = NULL;

	g_return_val_if_fail(context, FALSE);

	cipher = context->cipher;

	if(cipher->ops && cipher->ops->digest)
		return cipher->ops->digest(context, in_len, digest, out_len);
	else {
		purple_debug_warning("cipher", "the %s cipher does not support the digest "
						"operation\n", cipher->name);
		return FALSE;
	}
}

gboolean
purple_cipher_context_digest_to_str(PurpleCipherContext *context, size_t in_len,
								   gchar digest_s[], size_t *out_len)
{
	/* 8k is a bit excessive, will tweak later. */
	guchar digest[BUF_LEN * 4];
	gint n = 0;
	size_t dlen = 0;

	g_return_val_if_fail(context, FALSE);
	g_return_val_if_fail(digest_s, FALSE);

	if(!purple_cipher_context_digest(context, sizeof(digest), digest, &dlen))
		return FALSE;

	/* in_len must be greater than dlen * 2 so we have room for the NUL. */
	if(in_len <= dlen * 2)
		return FALSE;

	for(n = 0; n < dlen; n++)
		sprintf(digest_s + (n * 2), "%02x", digest[n]);

	digest_s[n * 2] = '\0';

	if(out_len)
		*out_len = dlen * 2;

	return TRUE;
}

gint
purple_cipher_context_encrypt(PurpleCipherContext *context, const guchar data[],
							size_t len, guchar output[], size_t *outlen)
{
	PurpleCipher *cipher = NULL;

	g_return_val_if_fail(context, -1);

	cipher = context->cipher;
	g_return_val_if_fail(cipher, -1);

	if(cipher->ops && cipher->ops->encrypt)
		return cipher->ops->encrypt(context, data, len, output, outlen);
	else {
		purple_debug_warning("cipher", "the %s cipher does not support the encrypt"
						"operation\n", cipher->name);

		if(outlen)
			*outlen = -1;

		return -1;
	}
}

gint
purple_cipher_context_decrypt(PurpleCipherContext *context, const guchar data[],
							size_t len, guchar output[], size_t *outlen)
{
	PurpleCipher *cipher = NULL;

	g_return_val_if_fail(context, -1);

	cipher = context->cipher;
	g_return_val_if_fail(cipher, -1);

	if(cipher->ops && cipher->ops->decrypt)
		return cipher->ops->decrypt(context, data, len, output, outlen);
	else {
		purple_debug_warning("cipher", "the %s cipher does not support the decrypt"
						"operation\n", cipher->name);

		if(outlen)
			*outlen = -1;

		return -1;
	}
}

void
purple_cipher_context_set_salt(PurpleCipherContext *context, guchar *salt) {
	PurpleCipher *cipher = NULL;

	g_return_if_fail(context);

	cipher = context->cipher;
	g_return_if_fail(cipher);

	if(cipher->ops && cipher->ops->set_salt)
		cipher->ops->set_salt(context, salt);
	else
		purple_debug_warning("cipher", "the %s cipher does not support the "
						"set_salt operation\n", cipher->name);
}

size_t
purple_cipher_context_get_salt_size(PurpleCipherContext *context) {
	PurpleCipher *cipher = NULL;

	g_return_val_if_fail(context, -1);

	cipher = context->cipher;
	g_return_val_if_fail(cipher, -1);

	if(cipher->ops && cipher->ops->get_salt_size)
		return cipher->ops->get_salt_size(context);
	else {
		purple_debug_warning("cipher", "the %s cipher does not support the "
						"get_salt_size operation\n", cipher->name);

		return -1;
	}
}

void
purple_cipher_context_set_key(PurpleCipherContext *context, const guchar *key) {
	PurpleCipher *cipher = NULL;

	g_return_if_fail(context);

	cipher = context->cipher;
	g_return_if_fail(cipher);

	if(cipher->ops && cipher->ops->set_key)
		cipher->ops->set_key(context, key);
	else
		purple_debug_warning("cipher", "the %s cipher does not support the "
						"set_key operation\n", cipher->name);
}

size_t
purple_cipher_context_get_key_size(PurpleCipherContext *context) {
	PurpleCipher *cipher = NULL;

	g_return_val_if_fail(context, -1);

	cipher = context->cipher;
	g_return_val_if_fail(cipher, -1);

	if(cipher->ops && cipher->ops->get_key_size)
		return cipher->ops->get_key_size(context);
	else {
		purple_debug_warning("cipher", "the %s cipher does not support the "
						"get_key_size operation\n", cipher->name);

		return -1;
	}
}

void
purple_cipher_context_set_batch_mode(PurpleCipherContext *context,
                                     PurpleCipherBatchMode mode)
{
	PurpleCipher *cipher = NULL;

	g_return_if_fail(context);

	cipher = context->cipher;
	g_return_if_fail(cipher);

	if(cipher->ops && cipher->ops->set_batch_mode)
		cipher->ops->set_batch_mode(context, mode);
	else
		purple_debug_warning("cipher", "The %s cipher does not support the "
		                            "set_batch_mode operation\n", cipher->name);
}

PurpleCipherBatchMode
purple_cipher_context_get_batch_mode(PurpleCipherContext *context)
{
	PurpleCipher *cipher = NULL;

	g_return_val_if_fail(context, -1);

	cipher = context->cipher;
	g_return_val_if_fail(cipher, -1);

	if(cipher->ops && cipher->ops->get_batch_mode)
		return cipher->ops->get_batch_mode(context);
	else {
		purple_debug_warning("cipher", "The %s cipher does not support the "
		                            "get_batch_mode operation\n", cipher->name);
		return -1;
	}
}

size_t
purple_cipher_context_get_block_size(PurpleCipherContext *context)
{
	PurpleCipher *cipher = NULL;

	g_return_val_if_fail(context, -1);

	cipher = context->cipher;
	g_return_val_if_fail(cipher, -1);

	if(cipher->ops && cipher->ops->get_block_size)
		return cipher->ops->get_block_size(context);
	else {
		purple_debug_warning("cipher", "The %s cipher does not support the "
		                            "get_block_size operation\n", cipher->name);
		return -1;
	}
}

void
purple_cipher_context_set_key_with_len(PurpleCipherContext *context,
                                       const guchar *key, size_t len)
{
	PurpleCipher *cipher = NULL;

	g_return_if_fail(context);

	cipher = context->cipher;
	g_return_if_fail(cipher);

	if(cipher->ops && cipher->ops->set_key_with_len)
		cipher->ops->set_key_with_len(context, key, len);
	else
		purple_debug_warning("cipher", "The %s cipher does not support the "
		                            "set_key_with_len operation\n", cipher->name);
}

void
purple_cipher_context_set_data(PurpleCipherContext *context, gpointer data) {
	g_return_if_fail(context);

	context->data = data;
}

gpointer
purple_cipher_context_get_data(PurpleCipherContext *context) {
	g_return_val_if_fail(context, NULL);

	return context->data;
}

gchar *purple_cipher_http_digest_calculate_session_key(
		const gchar *algorithm,
		const gchar *username,
		const gchar *realm,
		const gchar *password,
		const gchar *nonce,
		const gchar *client_nonce)
{
	PurpleCipher *cipher;
	PurpleCipherContext *context;
	gchar hash[33]; /* We only support MD5. */

	g_return_val_if_fail(username != NULL, NULL);
	g_return_val_if_fail(realm    != NULL, NULL);
	g_return_val_if_fail(password != NULL, NULL);
	g_return_val_if_fail(nonce    != NULL, NULL);

	/* Check for a supported algorithm. */
	g_return_val_if_fail(algorithm == NULL ||
						 *algorithm == '\0' ||
						 g_ascii_strcasecmp(algorithm, "MD5") ||
						 g_ascii_strcasecmp(algorithm, "MD5-sess"), NULL);

	cipher = purple_ciphers_find_cipher("md5");
	g_return_val_if_fail(cipher != NULL, NULL);

	context = purple_cipher_context_new(cipher, NULL);

	purple_cipher_context_append(context, (guchar *)username, strlen(username));
	purple_cipher_context_append(context, (guchar *)":", 1);
	purple_cipher_context_append(context, (guchar *)realm, strlen(realm));
	purple_cipher_context_append(context, (guchar *)":", 1);
	purple_cipher_context_append(context, (guchar *)password, strlen(password));

	if (algorithm != NULL && !g_ascii_strcasecmp(algorithm, "MD5-sess"))
	{
		guchar digest[16];

		if (client_nonce == NULL)
		{
			purple_cipher_context_destroy(context);
			purple_debug_error("cipher", "Required client_nonce missing for MD5-sess digest calculation.\n");
			return NULL;
		}

		purple_cipher_context_digest(context, sizeof(digest), digest, NULL);
		purple_cipher_context_destroy(context);

		context = purple_cipher_context_new(cipher, NULL);
		purple_cipher_context_append(context, digest, sizeof(digest));
		purple_cipher_context_append(context, (guchar *)":", 1);
		purple_cipher_context_append(context, (guchar *)nonce, strlen(nonce));
		purple_cipher_context_append(context, (guchar *)":", 1);
		purple_cipher_context_append(context, (guchar *)client_nonce, strlen(client_nonce));
	}

	purple_cipher_context_digest_to_str(context, sizeof(hash), hash, NULL);
	purple_cipher_context_destroy(context);

	return g_strdup(hash);
}

gchar *purple_cipher_http_digest_calculate_response(
		const gchar *algorithm,
		const gchar *method,
		const gchar *digest_uri,
		const gchar *qop,
		const gchar *entity,
		const gchar *nonce,
		const gchar *nonce_count,
		const gchar *client_nonce,
		const gchar *session_key)
{
	PurpleCipher *cipher;
	PurpleCipherContext *context;
	static gchar hash2[33]; /* We only support MD5. */

	g_return_val_if_fail(method      != NULL, NULL);
	g_return_val_if_fail(digest_uri  != NULL, NULL);
	g_return_val_if_fail(nonce       != NULL, NULL);
	g_return_val_if_fail(session_key != NULL, NULL);

	/* Check for a supported algorithm. */
	g_return_val_if_fail(algorithm == NULL ||
						 *algorithm == '\0' ||
						 g_ascii_strcasecmp(algorithm, "MD5") ||
						 g_ascii_strcasecmp(algorithm, "MD5-sess"), NULL);

	/* Check for a supported "quality of protection". */
	g_return_val_if_fail(qop == NULL ||
						 *qop == '\0' ||
						 g_ascii_strcasecmp(qop, "auth") ||
						 g_ascii_strcasecmp(qop, "auth-int"), NULL);

	cipher = purple_ciphers_find_cipher("md5");
	g_return_val_if_fail(cipher != NULL, NULL);

	context = purple_cipher_context_new(cipher, NULL);

	purple_cipher_context_append(context, (guchar *)method, strlen(method));
	purple_cipher_context_append(context, (guchar *)":", 1);
	purple_cipher_context_append(context, (guchar *)digest_uri, strlen(digest_uri));

	if (qop != NULL && !g_ascii_strcasecmp(qop, "auth-int"))
	{
		PurpleCipherContext *context2;
		gchar entity_hash[33];

		if (entity == NULL)
		{
			purple_cipher_context_destroy(context);
			purple_debug_error("cipher", "Required entity missing for auth-int digest calculation.\n");
			return NULL;
		}

		context2 = purple_cipher_context_new(cipher, NULL);
		purple_cipher_context_append(context2, (guchar *)entity, strlen(entity));
		purple_cipher_context_digest_to_str(context2, sizeof(entity_hash), entity_hash, NULL);
		purple_cipher_context_destroy(context2);

		purple_cipher_context_append(context, (guchar *)":", 1);
		purple_cipher_context_append(context, (guchar *)entity_hash, strlen(entity_hash));
	}

	purple_cipher_context_digest_to_str(context, sizeof(hash2), hash2, NULL);
	purple_cipher_context_destroy(context);

	context = purple_cipher_context_new(cipher, NULL);
	purple_cipher_context_append(context, (guchar *)session_key, strlen(session_key));
	purple_cipher_context_append(context, (guchar *)":", 1);
	purple_cipher_context_append(context, (guchar *)nonce, strlen(nonce));
	purple_cipher_context_append(context, (guchar *)":", 1);

	if (qop != NULL && *qop != '\0')
	{
		if (nonce_count == NULL)
		{
			purple_cipher_context_destroy(context);
			purple_debug_error("cipher", "Required nonce_count missing for digest calculation.\n");
			return NULL;
		}

		if (client_nonce == NULL)
		{
			purple_cipher_context_destroy(context);
			purple_debug_error("cipher", "Required client_nonce missing for digest calculation.\n");
			return NULL;
		}

		purple_cipher_context_append(context, (guchar *)nonce_count, strlen(nonce_count));
		purple_cipher_context_append(context, (guchar *)":", 1);
		purple_cipher_context_append(context, (guchar *)client_nonce, strlen(client_nonce));
		purple_cipher_context_append(context, (guchar *)":", 1);

		purple_cipher_context_append(context, (guchar *)qop, strlen(qop));

		purple_cipher_context_append(context, (guchar *)":", 1);
	}

	purple_cipher_context_append(context, (guchar *)hash2, strlen(hash2));
	purple_cipher_context_digest_to_str(context, sizeof(hash2), hash2, NULL);
	purple_cipher_context_destroy(context);

	return g_strdup(hash2);
}