/*
 *  ircd-hybrid: an advanced Internet Relay Chat Daemon(ircd).
 *  crypt.c: Provides MD5 password crypt() functions.
 *
 *  ----------------------------------------------------------------------------
 *  "THE BEER-WARE LICENSE" (Revision 42):
 *  <phk@login.dknet.dk> wrote this file.  As long as you retain this notice you
 *  can do whatever you want with this stuff. If we meet some day, and you think
 *  this stuff is worth it, you can buy me a beer in return.  Poul-Henning Kamp
 *  ----------------------------------------------------------------------------
 *  
 *  $Id: crypt.c,v 1.3 2003/08/14 07:51:19 stu Exp $
 */

#include "stdinc.h"

#define MD5_SIZE 16

/* MD5 context. */
typedef struct MD5Context {
  u_int32_t state[4];   /* state (ABCD) */
  u_int32_t count[2];   /* number of bits, modulo 2^64 (lsb first) */
  unsigned char buffer[64];     /* input buffer */
} MD5_CTX;

void   MD5Init (MD5_CTX *);
void   MD5Update (MD5_CTX *, const unsigned char *, unsigned int);
void   MD5Pad (MD5_CTX *);
void   MD5Final (unsigned char [16], MD5_CTX *);
char * MD5End(MD5_CTX *, char *);
char * MD5File(const char *, char *);
char * MD5Data(const unsigned char *, unsigned int, char *);

static unsigned char itoa64[] =         /* 0 ... 63 => ascii - 64 */
        "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

void
_crypt_to64(s, v, n)
        char *s;
        unsigned long v;
        int n;
{
        while (--n >= 0) {
                *s++ = itoa64[v&0x3f];
                v >>= 6;
        }
}

/*
 * UNIX password
 */

char *
crypt(const char *pw, const char *salt)
{
	static char	*magic = "$1$";	/*
					 * This string is magic for
					 * this algorithm.  Having
					 * it this way, we can get
					 * get better later on
					 */
	static char     passwd[120], *p;
	static const char *sp,*ep;
	unsigned char	final[MD5_SIZE];
	int sl,pl,i;
	MD5_CTX	ctx,ctx1;
	unsigned long l;

	/* Refine the Salt first */
	sp = salt;

	/* If it starts with the magic string, then skip that */
	if(!strncmp(sp,magic,strlen(magic)))
		sp += strlen(magic);

	/* It stops at the first '$', max 8 chars */
	for(ep=sp;*ep && *ep != '$' && ep < (sp+8);ep++)
		continue;

	/* get the length of the true salt */
	sl = ep - sp;

	MD5Init(&ctx);

	/* The password first, since that is what is most unknown */
	MD5Update(&ctx,(const unsigned char *)pw,strlen(pw));

	/* Then our magic string */
	MD5Update(&ctx,(const unsigned char *)magic,strlen(magic));

	/* Then the raw salt */
	MD5Update(&ctx,(const unsigned char *)sp,sl);

	/* Then just as many characters of the MD5(pw,salt,pw) */
	MD5Init(&ctx1);
	MD5Update(&ctx1,(const unsigned char *)pw,strlen(pw));
	MD5Update(&ctx1,(const unsigned char *)sp,sl);
	MD5Update(&ctx1,(const unsigned char *)pw,strlen(pw));
	MD5Final(final,&ctx1);
	for(pl = strlen(pw); pl > 0; pl -= MD5_SIZE)
		MD5Update(&ctx,final,pl>MD5_SIZE ? MD5_SIZE : pl);

	/* Don't leave anything around in vm they could use. */
	memset(final,0,sizeof final);

	/* Then something really weird... */
	for (i = strlen(pw); i ; i >>= 1)
		if(i&1)
		    MD5Update(&ctx, final, 1);
		else
		    MD5Update(&ctx, (const unsigned char *)pw, 1);

	/* Now make the output string */
	strcpy(passwd,magic);
	strncat(passwd,sp,sl);
	strcat(passwd,"$");

	MD5Final(final,&ctx);

	/*
	 * and now, just to make sure things don't run too fast
	 * On a 60 Mhz Pentium this takes 34 msec, so you would
	 * need 30 seconds to build a 1000 entry dictionary...
	 */
	for(i=0;i<1000;i++) {
		MD5Init(&ctx1);
		if(i & 1)
			MD5Update(&ctx1,(const unsigned char *)pw,strlen(pw));
		else
			MD5Update(&ctx1,final,MD5_SIZE);

		if(i % 3)
			MD5Update(&ctx1,(const unsigned char *)sp,sl);

		if(i % 7)
			MD5Update(&ctx1,(const unsigned char *)pw,strlen(pw));

		if(i & 1)
			MD5Update(&ctx1,final,MD5_SIZE);
		else
			MD5Update(&ctx1,(const unsigned char *)pw,strlen(pw));
		MD5Final(final,&ctx1);
	}

	p = passwd + strlen(passwd);

	l = (final[ 0]<<16) | (final[ 6]<<8) | final[12];
	_crypt_to64(p,l,4); p += 4;
	l = (final[ 1]<<16) | (final[ 7]<<8) | final[13];
	_crypt_to64(p,l,4); p += 4;
	l = (final[ 2]<<16) | (final[ 8]<<8) | final[14];
	_crypt_to64(p,l,4); p += 4;
	l = (final[ 3]<<16) | (final[ 9]<<8) | final[15];
	_crypt_to64(p,l,4); p += 4;
	l = (final[ 4]<<16) | (final[10]<<8) | final[ 5];
	_crypt_to64(p,l,4); p += 4;
	l =                    final[11]                ;
	_crypt_to64(p,l,2); p += 2;
	*p = '\0';

	/* Don't leave anything around in vm they could use. */
	memset(final,0,sizeof final);

	return passwd;
}

/*
 * MD5C.C - RSA Data Security, Inc., MD5 message-digest algorithm
 *
 * Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
 * rights reserved.
 *
 * License to copy and use this software is granted provided that it
 * is identified as the "RSA Data Security, Inc. MD5 Message-Digest
 * Algorithm" in all material mentioning or referencing this software
 * or this function.
 *
 * License is also granted to make and use derivative works provided
 * that such works are identified as "derived from the RSA Data
 * Security, Inc. MD5 Message-Digest Algorithm" in all material
 * mentioning or referencing the derived work.
 *
 * RSA Data Security, Inc. makes no representations concerning either
 * the merchantability of this software or the suitability of this
 * software for any particular purpose. It is provided "as is"
 * without express or implied warranty of any kind.
 *
 * These notices must be retained in any copies of any part of this
 * documentation and/or software.
 *
 * $FreeBSD: src/lib/libmd/md5c.c,v 1.11 1999/12/29 05:04:20 peter Exp $
 *
 * This code is the same as the code published by RSA Inc.  It has been
 * edited for clarity and style only.
 */

static void MD5Transform (u_int32_t [4], const unsigned char [64]);

/*
 * Encodes input (u_int32_t) into output (unsigned char). Assumes len is
 * a multiple of 4.
 */

static void
Encode (output, input, len)
	unsigned char *output;
	u_int32_t *input;
	unsigned int len;
{
	unsigned int i, j;

	for (i = 0, j = 0; j < len; i++, j += 4) {
		output[j] = (unsigned char)(input[i] & 0xff);
		output[j+1] = (unsigned char)((input[i] >> 8) & 0xff);
		output[j+2] = (unsigned char)((input[i] >> 16) & 0xff);
		output[j+3] = (unsigned char)((input[i] >> 24) & 0xff);
	}
}

/*
 * Decodes input (unsigned char) into output (u_int32_t). Assumes len is
 * a multiple of 4.
 */

static void
Decode (output, input, len)
	u_int32_t *output;
	const unsigned char *input;
	unsigned int len;
{
	unsigned int i, j;

	for (i = 0, j = 0; j < len; i++, j += 4)
		output[i] = ((u_int32_t)input[j]) | (((u_int32_t)input[j+1]) << 8) |
		    (((u_int32_t)input[j+2]) << 16) | (((u_int32_t)input[j+3]) << 24);
}

static unsigned char PADDING[64] = {
  0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

/* F, G, H and I are basic MD5 functions. */
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

/* ROTATE_LEFT rotates x left n bits. */
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

/*
 * FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
 * Rotation is separate from addition to prevent recomputation.
 */
#define FF(a, b, c, d, x, s, ac) { \
	(a) += F ((b), (c), (d)) + (x) + (u_int32_t)(ac); \
	(a) = ROTATE_LEFT ((a), (s)); \
	(a) += (b); \
	}
#define GG(a, b, c, d, x, s, ac) { \
	(a) += G ((b), (c), (d)) + (x) + (u_int32_t)(ac); \
	(a) = ROTATE_LEFT ((a), (s)); \
	(a) += (b); \
	}
#define HH(a, b, c, d, x, s, ac) { \
	(a) += H ((b), (c), (d)) + (x) + (u_int32_t)(ac); \
	(a) = ROTATE_LEFT ((a), (s)); \
	(a) += (b); \
	}
#define II(a, b, c, d, x, s, ac) { \
	(a) += I ((b), (c), (d)) + (x) + (u_int32_t)(ac); \
	(a) = ROTATE_LEFT ((a), (s)); \
	(a) += (b); \
	}

/* MD5 initialization. Begins an MD5 operation, writing a new context. */

void
MD5Init (context)
	MD5_CTX *context;
{

	context->count[0] = context->count[1] = 0;

	/* Load magic initialization constants.  */
	context->state[0] = 0x67452301;
	context->state[1] = 0xefcdab89;
	context->state[2] = 0x98badcfe;
	context->state[3] = 0x10325476;
}

/* 
 * MD5 block update operation. Continues an MD5 message-digest
 * operation, processing another message block, and updating the
 * context.
 */

void
MD5Update (context, input, inputLen)
	MD5_CTX *context;
	const unsigned char *input;
	unsigned int inputLen;
{
	unsigned int i, index, partLen;

	/* Compute number of bytes mod 64 */
	index = (unsigned int)((context->count[0] >> 3) & 0x3F);

	/* Update number of bits */
	if ((context->count[0] += ((u_int32_t)inputLen << 3))
	    < ((u_int32_t)inputLen << 3))
		context->count[1]++;
	context->count[1] += ((u_int32_t)inputLen >> 29);

	partLen = 64 - index;

	/* Transform as many times as possible. */
	if (inputLen >= partLen) {
		memcpy((void *)&context->buffer[index], (const void *)input,
		    partLen);
		MD5Transform (context->state, context->buffer);

		for (i = partLen; i + 63 < inputLen; i += 64)
			MD5Transform (context->state, &input[i]);

		index = 0;
	}
	else
		i = 0;

	/* Buffer remaining input */
	memcpy ((void *)&context->buffer[index], (const void *)&input[i],
	    inputLen-i);
}

/*
 * MD5 padding. Adds padding followed by original length.
 */

void
MD5Pad (context)
	MD5_CTX *context;
{
	unsigned char bits[8];
	unsigned int index, padLen;

	/* Save number of bits */
	Encode (bits, context->count, 8);

	/* Pad out to 56 mod 64. */
	index = (unsigned int)((context->count[0] >> 3) & 0x3f);
	padLen = (index < 56) ? (56 - index) : (120 - index);
	MD5Update (context, PADDING, padLen);

	/* Append length (before padding) */
	MD5Update (context, bits, 8);
}

/*
 * MD5 finalization. Ends an MD5 message-digest operation, writing the
 * the message digest and zeroizing the context.
 */

void
MD5Final (digest, context)
	unsigned char digest[16];
	MD5_CTX *context;
{
	/* Do padding. */
	MD5Pad (context);

	/* Store state in digest */
	Encode (digest, context->state, 16);

	/* Zeroize sensitive information. */
	memset ((void *)context, 0, sizeof (*context));
}

/* MD5 basic transformation. Transforms state based on block. */

static void
MD5Transform (state, block)
	u_int32_t state[4];
	const unsigned char block[64];
{
	u_int32_t a = state[0], b = state[1], c = state[2], d = state[3], x[16];

	Decode (x, block, 64);

	/* Round 1 */
#define S11 7
#define S12 12
#define S13 17
#define S14 22
	FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */
	FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */
	FF (c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */
	FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */
	FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */
	FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */
	FF (c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */
	FF (b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */
	FF (a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */
	FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */
	FF (c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
	FF (b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
	FF (a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
	FF (d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
	FF (c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
	FF (b, c, d, a, x[15], S14, 0x49b40821); /* 16 */

	/* Round 2 */
#define S21 5
#define S22 9
#define S23 14
#define S24 20
	GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */
	GG (d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */
	GG (c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
	GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */
	GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */
	GG (d, a, b, c, x[10], S22,  0x2441453); /* 22 */
	GG (c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
	GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */
	GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */
	GG (d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
	GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */
	GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */
	GG (a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
	GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */
	GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */
	GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */

	/* Round 3 */
#define S31 4
#define S32 11
#define S33 16
#define S34 23
	HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */
	HH (d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */
	HH (c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
	HH (b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
	HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */
	HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */
	HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */
	HH (b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
	HH (a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
	HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */
	HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */
	HH (b, c, d, a, x[ 6], S34,  0x4881d05); /* 44 */
	HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */
	HH (d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
	HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
	HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */

	/* Round 4 */
#define S41 6
#define S42 10
#define S43 15
#define S44 21
	II (a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */
	II (d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */
	II (c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
	II (b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */
	II (a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
	II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */
	II (c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
	II (b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */
	II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */
	II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
	II (c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */
	II (b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
	II (a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */
	II (d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
	II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */
	II (b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */

	state[0] += a;
	state[1] += b;
	state[2] += c;
	state[3] += d;

	/* Zeroize sensitive information. */
	memset ((void *)x, 0, sizeof (x));
}
