/*
 * ppp_mppe_crypto.c - cryptografic funtions for MPPE
 *
 *  This code is Public Domain. Please see comments below.
 *
 *  I have just put SHA1 and ARCFOUR implementations into one file
 *  in order to not pollute kernel namespace. 
 *
 *  Jan Dubiec <jdx@slackware.pl>, 2003-07-08
 */

/*
 * ftp://ftp.funet.fi/pub/crypt/hash/sha/sha1.c
 * 
 * SHA-1 in C
 * By Steve Reid <steve@edmweb.com>
 * 100% Public Domain
 * 
 * Test Vectors (from FIPS PUB 180-1)
 * "abc"
 * A9993E36 4706816A BA3E2571 7850C26C 9CD0D89D
 * "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq"
 * 84983E44 1C3BD26E BAAE4AA1 F95129E5 E54670F1
 * A million repetitions of "a"
 * 34AA973C D4C4DAA4 F61EEB2B DBAD2731 6534016F
 */

/* #define SHA1HANDSOFF * Copies data before messing with it. */

#if defined(__linux__)
#include <asm/byteorder.h>
#include <linux/string.h>
#elif defined(__solaris__)
#include <sys/isa_defs.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#define memcpy(d, s, c) bcopy(s, d, c)
#define memset(d, b, c) bzero(d, c)
#endif

#include "ppp_mppe_crypto.h"

static void SHA1_Transform(unsigned long[5], const unsigned char[64]);

#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

/* blk0() and blk() perform the initial expand. */
/* I got the idea of expanding during the round function from SSLeay */
#if defined(__LITTLE_ENDIAN) || defined(_LITTLE_ENDIAN)
#define blk0(i) (block->l[i] = (rol(block->l[i],24)&0xFF00FF00) \
    |(rol(block->l[i],8)&0x00FF00FF))
#elif defined(__BIG_ENDIAN) || defined(_BIG_ENDIAN)
#define blk0(i) block->l[i]
#else
#error Endianness not defined
#endif
#define blk(i) (block->l[i&15] = rol(block->l[(i+13)&15]^block->l[(i+8)&15] \
    ^block->l[(i+2)&15]^block->l[i&15],1))

/* (R0+R1), R2, R3, R4 are the different operations used in SHA1 */
#define R0(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk0(i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R1(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk(i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R2(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0x6ED9EBA1+rol(v,5);w=rol(w,30);
#define R3(v,w,x,y,z,i) z+=(((w|x)&y)|(w&x))+blk(i)+0x8F1BBCDC+rol(v,5);w=rol(w,30);
#define R4(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0xCA62C1D6+rol(v,5);w=rol(w,30);

/* Hash a single 512-bit block. This is the core of the algorithm. */
static void
SHA1_Transform(unsigned long state[5], const unsigned char buffer[64])
{
    unsigned long a, b, c, d, e;
    typedef union {
	unsigned char c[64];
	unsigned long l[16];
    } CHAR64LONG16;
    CHAR64LONG16 *block;

#ifdef SHA1HANDSOFF
    static unsigned char workspace[64];
    block = (CHAR64LONG16 *) workspace;
    memcpy(block, buffer, 64);
#else
    block = (CHAR64LONG16 *) buffer;
#endif
    /* Copy context->state[] to working vars */
    a = state[0];
    b = state[1];
    c = state[2];
    d = state[3];
    e = state[4];
    /* 4 rounds of 20 operations each. Loop unrolled. */
    R0(a,b,c,d,e, 0); R0(e,a,b,c,d, 1); R0(d,e,a,b,c, 2); R0(c,d,e,a,b, 3);
    R0(b,c,d,e,a, 4); R0(a,b,c,d,e, 5); R0(e,a,b,c,d, 6); R0(d,e,a,b,c, 7);
    R0(c,d,e,a,b, 8); R0(b,c,d,e,a, 9); R0(a,b,c,d,e,10); R0(e,a,b,c,d,11);
    R0(d,e,a,b,c,12); R0(c,d,e,a,b,13); R0(b,c,d,e,a,14); R0(a,b,c,d,e,15);
    R1(e,a,b,c,d,16); R1(d,e,a,b,c,17); R1(c,d,e,a,b,18); R1(b,c,d,e,a,19);
    R2(a,b,c,d,e,20); R2(e,a,b,c,d,21); R2(d,e,a,b,c,22); R2(c,d,e,a,b,23);
    R2(b,c,d,e,a,24); R2(a,b,c,d,e,25); R2(e,a,b,c,d,26); R2(d,e,a,b,c,27);
    R2(c,d,e,a,b,28); R2(b,c,d,e,a,29); R2(a,b,c,d,e,30); R2(e,a,b,c,d,31);
    R2(d,e,a,b,c,32); R2(c,d,e,a,b,33); R2(b,c,d,e,a,34); R2(a,b,c,d,e,35);
    R2(e,a,b,c,d,36); R2(d,e,a,b,c,37); R2(c,d,e,a,b,38); R2(b,c,d,e,a,39);
    R3(a,b,c,d,e,40); R3(e,a,b,c,d,41); R3(d,e,a,b,c,42); R3(c,d,e,a,b,43);
    R3(b,c,d,e,a,44); R3(a,b,c,d,e,45); R3(e,a,b,c,d,46); R3(d,e,a,b,c,47);
    R3(c,d,e,a,b,48); R3(b,c,d,e,a,49); R3(a,b,c,d,e,50); R3(e,a,b,c,d,51);
    R3(d,e,a,b,c,52); R3(c,d,e,a,b,53); R3(b,c,d,e,a,54); R3(a,b,c,d,e,55);
    R3(e,a,b,c,d,56); R3(d,e,a,b,c,57); R3(c,d,e,a,b,58); R3(b,c,d,e,a,59);
    R4(a,b,c,d,e,60); R4(e,a,b,c,d,61); R4(d,e,a,b,c,62); R4(c,d,e,a,b,63);
    R4(b,c,d,e,a,64); R4(a,b,c,d,e,65); R4(e,a,b,c,d,66); R4(d,e,a,b,c,67);
    R4(c,d,e,a,b,68); R4(b,c,d,e,a,69); R4(a,b,c,d,e,70); R4(e,a,b,c,d,71);
    R4(d,e,a,b,c,72); R4(c,d,e,a,b,73); R4(b,c,d,e,a,74); R4(a,b,c,d,e,75);
    R4(e,a,b,c,d,76); R4(d,e,a,b,c,77); R4(c,d,e,a,b,78); R4(b,c,d,e,a,79);
    /* Add the working vars back into context.state[] */
    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
    state[4] += e;
    /* Wipe variables */
    a = b = c = d = e = 0;
}

/* SHA1Init - Initialize new context */
void
SHA1_Init(SHA1_CTX *context)
{
    /* SHA1 initialization constants */
    context->state[0] = 0x67452301;
    context->state[1] = 0xEFCDAB89;
    context->state[2] = 0x98BADCFE;
    context->state[3] = 0x10325476;
    context->state[4] = 0xC3D2E1F0;
    context->count[0] = context->count[1] = 0;
}

/* Run your data through this. */
void
SHA1_Update(SHA1_CTX *context, const unsigned char *data, unsigned int len)
{
    unsigned int i, j;

    j = (context->count[0] >> 3) & 63;
    if ((context->count[0] += len << 3) < (len << 3)) context->count[1]++;
    context->count[1] += (len >> 29);
    if ((j + len) > 63) {
	memcpy(&context->buffer[j], data, (i = 64-j));
	SHA1_Transform(context->state, context->buffer);
	for ( ; i + 63 < len; i += 64) {
	    SHA1_Transform(context->state, &data[i]);
	}
	j = 0;
    }
    else
	i = 0;

    memcpy(&context->buffer[j], &data[i], len - i);
}

/* Add padding and return the message digest. */
void
SHA1_Final(unsigned char digest[20], SHA1_CTX *context)
{
    unsigned long i, j;
    unsigned char finalcount[8];

    for (i = 0; i < 8; i++) {
        finalcount[i] = (unsigned char)((context->count[(i >= 4 ? 0 : 1)]
         >> ((3-(i & 3)) * 8) ) & 255);  /* Endian independent */
    }
    SHA1_Update(context, (unsigned char *) "\200", 1);
    while ((context->count[0] & 504) != 448) {
	SHA1_Update(context, (unsigned char *) "\0", 1);
    }
    SHA1_Update(context, finalcount, 8);  /* Should cause a SHA1Transform() */
    for (i = 0; i < 20; i++) {
	digest[i] = (unsigned char)
		     ((context->state[i>>2] >> ((3-(i & 3)) * 8) ) & 255);
    }
    /* Wipe variables */
    i = j = 0;
    memset(context->buffer, 0, 64);
    memset(context->state, 0, 20);
    memset(context->count, 0, 8);
    memset(&finalcount, 0, 8);
#ifdef SHA1HANDSOFF  /* make SHA1Transform overwrite it's own static vars */
    SHA1Transform(context->state, context->buffer);
#endif
}

/*
 * arcfour.c
 * by Frank Cusack <frank@google.com>
 * 100% public domain
 *
 * Implemented from the description in _Applied Cryptography_, 2nd ed.
 *
 * ** Distribution ** of this software is unlimited and unrestricted.
 *
 * ** Use ** of this software is almost certainly legal; however, refer
 * to <http://theory.lcs.mit.edu/~rivest/faq.html>.
 */

#define swap(a, b)		\
{				\
    unsigned char t = b;	\
    b = a;			\
    a = t;			\
}

/*
 * Initialize arcfour from a key.
 */
void
arcfour_setkey(arcfour_context *context, const unsigned char *key,
	       unsigned keylen)
{
    unsigned i, j;
    unsigned char K[256];

    context->i = context->j = 0;

    for (i = 0; i < 256; i++) {
	context->S[i] = i;
	K[i] = key[i % keylen];
    }

    j = 0;
    for (i = 0; i < 256; i++) {
	j = (j + context->S[i] + K[i]) % 256;
	swap(context->S[i], context->S[j]);
    }

    memset(K, 0, sizeof(K));
}

/*
 * plaintext -> ciphertext (or vice versa)
 */
void
arcfour_encrypt(arcfour_context *context, const unsigned char *in, unsigned len,
		unsigned char *out)
{
    unsigned i = context->i;
    unsigned j = context->j;
    unsigned char *S = context->S;
    unsigned char K;

    while (len--) {
	i = (i + 1) % 256;
	j = (j + S[i]) % 256;
	swap(S[i], S[j]);
	K = S[(S[i] + S[j]) % 256];
	*out++ = *in++ ^ K;
    }

    context->i = i;
    context->j = j;
}
