/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "mozilla/Assertions.h"

#include "mozilla/EndianUtils.h"

#include "mozilla/SHA1.h"

#include <string.h>

using mozilla::NativeEndian;

using mozilla::SHA1Sum;

static inline uint32_t

SHA_ROTL(uint32_t aT, uint32_t aN)

{

  MOZ_ASSERT(aN < 32);

  return (aT << aN) | (aT >> (32 - aN));

}

static void

shaCompress(volatile unsigned* aX, const uint32_t* aBuf);

#define SHA_F1(X, Y, Z) ((((Y) ^ (Z)) & (X)) ^ (Z))

#define SHA_F2(X, Y, Z) ((X) ^ (Y) ^ (Z))

#define SHA_F3(X, Y, Z) (((X) & (Y)) | ((Z) & ((X) | (Y))))

#define SHA_F4(X, Y, Z) ((X) ^ (Y) ^ (Z))

#define SHA_MIX(n, a, b, c)    XW(n) = SHA_ROTL(XW(a) ^ XW(b) ^ XW(c) ^XW(n), 1)

SHA1Sum::SHA1Sum()

  : mSize(0), mDone(false)

{

  // Initialize H with constants from FIPS180-1.

  mH[0] = 0x67452301L;

  mH[1] = 0xefcdab89L;

  mH[2] = 0x98badcfeL;

  mH[3] = 0x10325476L;

  mH[4] = 0xc3d2e1f0L;

}

/*

 * Explanation of H array and index values:

 *

 * The context's H array is actually the concatenation of two arrays

 * defined by SHA1, the H array of state variables (5 elements),

 * and the W array of intermediate values, of which there are 16 elements.

 * The W array starts at H[5], that is W[0] is H[5].

 * Although these values are defined as 32-bit values, we use 64-bit

 * variables to hold them because the AMD64 stores 64 bit values in

 * memory MUCH faster than it stores any smaller values.

 *

 * Rather than passing the context structure to shaCompress, we pass

 * this combined array of H and W values.  We do not pass the address

 * of the first element of this array, but rather pass the address of an

 * element in the middle of the array, element X.  Presently X[0] is H[11].

 * So we pass the address of H[11] as the address of array X to shaCompress.

 * Then shaCompress accesses the members of the array using positive AND

 * negative indexes.

 *

 * Pictorially: (each element is 8 bytes)

 * H | H0 H1 H2 H3 H4 W0 W1 W2 W3 W4 W5 W6 W7 W8 W9 Wa Wb Wc Wd We Wf |

 * X |-11-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 X0 X1 X2 X3 X4 X5 X6 X7 X8 X9 |

 *

 * The byte offset from X[0] to any member of H and W is always

 * representable in a signed 8-bit value, which will be encoded

 * as a single byte offset in the X86-64 instruction set.

 * If we didn't pass the address of H[11], and instead passed the

 * address of H[0], the offsets to elements H[16] and above would be

 * greater than 127, not representable in a signed 8-bit value, and the

 * x86-64 instruction set would encode every such offset as a 32-bit

 * signed number in each instruction that accessed element H[16] or

 * higher.  This results in much bigger and slower code.

 */

#define H2X 11 /* X[0] is H[11], and H[0] is X[-11] */

#define W2X  6 /* X[0] is W[6],  and W[0] is X[-6]  */

/*

 *  SHA: Add data to context.

 */

void

SHA1Sum::update(const void* aData, uint32_t aLen)

{

  MOZ_ASSERT(!mDone, "SHA1Sum can only be used to compute a single hash.");

  const uint8_t* data = static_cast<const uint8_t*>(aData);

  if (aLen == 0) {

    return;

  }

  /* Accumulate the byte count. */

  unsigned int lenB = static_cast<unsigned int>(mSize) & 63U;

  mSize += aLen;

  /* Read the data into W and process blocks as they get full. */

  unsigned int togo;

  if (lenB > 0) {

    togo = 64U - lenB;

    if (aLen < togo) {

      togo = aLen;

    }

    memcpy(mU.mB + lenB, data, togo);

    aLen -= togo;

    data += togo;

    lenB = (lenB + togo) & 63U;

    if (!lenB) {

      shaCompress(&mH[H2X], mU.mW);

    }

  }

  while (aLen >= 64U) {

    aLen -= 64U;

    shaCompress(&mH[H2X], reinterpret_cast<const uint32_t*>(data));

    data += 64U;

  }

  if (aLen > 0) {

    memcpy(mU.mB, data, aLen);

  }

}

/*

 *  SHA: Generate hash value

 */

void

SHA1Sum::finish(SHA1Sum::Hash& aHashOut)

{

  MOZ_ASSERT(!mDone, "SHA1Sum can only be used to compute a single hash.");

  uint64_t size = mSize;

  uint32_t lenB = uint32_t(size) & 63;

  static const uint8_t bulk_pad[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 };

  /* Pad with a binary 1 (e.g. 0x80), then zeroes, then length in bits. */

  update(bulk_pad, (((55 + 64) - lenB) & 63) + 1);

  MOZ_ASSERT((uint32_t(mSize) & 63) == 56);

  /* Convert size from bytes to bits. */

  size <<= 3;

  mU.mW[14] = NativeEndian::swapToBigEndian(uint32_t(size >> 32));

  mU.mW[15] = NativeEndian::swapToBigEndian(uint32_t(size));

  shaCompress(&mH[H2X], mU.mW);

  /* Output hash. */

  mU.mW[0] = NativeEndian::swapToBigEndian(mH[0]);

  mU.mW[1] = NativeEndian::swapToBigEndian(mH[1]);

  mU.mW[2] = NativeEndian::swapToBigEndian(mH[2]);

  mU.mW[3] = NativeEndian::swapToBigEndian(mH[3]);

  mU.mW[4] = NativeEndian::swapToBigEndian(mH[4]);

  memcpy(aHashOut, mU.mW, 20);

  mDone = true;

}

/*

 *  SHA: Compression function, unrolled.

 *

 * Some operations in shaCompress are done as 5 groups of 16 operations.

 * Others are done as 4 groups of 20 operations.

 * The code below shows that structure.

 *

 * The functions that compute the new values of the 5 state variables

 * A-E are done in 4 groups of 20 operations (or you may also think

 * of them as being done in 16 groups of 5 operations).  They are

 * done by the SHA_RNDx macros below, in the right column.

 *

 * The functions that set the 16 values of the W array are done in

 * 5 groups of 16 operations.  The first group is done by the

 * LOAD macros below, the latter 4 groups are done by SHA_MIX below,

 * in the left column.

 *

 * gcc's optimizer observes that each member of the W array is assigned

 * a value 5 times in this code.  It reduces the number of store

 * operations done to the W array in the context (that is, in the X array)

 * by creating a W array on the stack, and storing the W values there for

 * the first 4 groups of operations on W, and storing the values in the

 * context's W array only in the fifth group.  This is undesirable.

 * It is MUCH bigger code than simply using the context's W array, because

 * all the offsets to the W array in the stack are 32-bit signed offsets,

 * and it is no faster than storing the values in the context's W array.

 *

 * The original code for sha_fast.c prevented this creation of a separate

 * W array in the stack by creating a W array of 80 members, each of

 * whose elements is assigned only once. It also separated the computations

 * of the W array values and the computations of the values for the 5

 * state variables into two separate passes, W's, then A-E's so that the

 * second pass could be done all in registers (except for accessing the W

 * array) on machines with fewer registers.  The method is suboptimal

 * for machines with enough registers to do it all in one pass, and it

 * necessitates using many instructions with 32-bit offsets.

 *

 * This code eliminates the separate W array on the stack by a completely

 * different means: by declaring the X array volatile.  This prevents

 * the optimizer from trying to reduce the use of the X array by the

 * creation of a MORE expensive W array on the stack. The result is

 * that all instructions use signed 8-bit offsets and not 32-bit offsets.

 *

 * The combination of this code and the -O3 optimizer flag on GCC 3.4.3

 * results in code that is 3 times faster than the previous NSS sha_fast

 * code on AMD64.

 */

static void

shaCompress(volatile unsigned* aX, const uint32_t* aBuf)

{

  unsigned A, B, C, D, E;

#define XH(n) aX[n - H2X]

#define XW(n) aX[n - W2X]

#define K0 0x5a827999L

#define K1 0x6ed9eba1L

#define K2 0x8f1bbcdcL

#define K3 0xca62c1d6L

#define SHA_RND1(a, b, c, d, e, n) \

  a = SHA_ROTL(b, 5) + SHA_F1(c, d, e) + a + XW(n) + K0; c = SHA_ROTL(c, 30)

#define SHA_RND2(a, b, c, d, e, n) \

  a = SHA_ROTL(b, 5) + SHA_F2(c, d, e) + a + XW(n) + K1; c = SHA_ROTL(c, 30)

#define SHA_RND3(a, b, c, d, e, n) \

  a = SHA_ROTL(b, 5) + SHA_F3(c, d, e) + a + XW(n) + K2; c = SHA_ROTL(c, 30)

#define SHA_RND4(a, b, c, d, e, n) \

  a = SHA_ROTL(b ,5) + SHA_F4(c, d, e) + a + XW(n) + K3; c = SHA_ROTL(c, 30)

#define LOAD(n) XW(n) = NativeEndian::swapToBigEndian(aBuf[n])

  A = XH(0);

  B = XH(1);

  C = XH(2);

  D = XH(3);

  E = XH(4);

  LOAD(0);       SHA_RND1(E,A,B,C,D, 0);

  LOAD(1);       SHA_RND1(D,E,A,B,C, 1);

  LOAD(2);       SHA_RND1(C,D,E,A,B, 2);

  LOAD(3);       SHA_RND1(B,C,D,E,A, 3);

  LOAD(4);       SHA_RND1(A,B,C,D,E, 4);

  LOAD(5);       SHA_RND1(E,A,B,C,D, 5);

  LOAD(6);       SHA_RND1(D,E,A,B,C, 6);

  LOAD(7);       SHA_RND1(C,D,E,A,B, 7);

  LOAD(8);       SHA_RND1(B,C,D,E,A, 8);

  LOAD(9);       SHA_RND1(A,B,C,D,E, 9);

  LOAD(10);      SHA_RND1(E,A,B,C,D,10);

  LOAD(11);      SHA_RND1(D,E,A,B,C,11);

  LOAD(12);      SHA_RND1(C,D,E,A,B,12);

  LOAD(13);      SHA_RND1(B,C,D,E,A,13);

  LOAD(14);      SHA_RND1(A,B,C,D,E,14);

  LOAD(15);      SHA_RND1(E,A,B,C,D,15);

  SHA_MIX( 0, 13,  8,  2); SHA_RND1(D,E,A,B,C, 0);

  SHA_MIX( 1, 14,  9,  3); SHA_RND1(C,D,E,A,B, 1);

  SHA_MIX( 2, 15, 10,  4); SHA_RND1(B,C,D,E,A, 2);

  SHA_MIX( 3,  0, 11,  5); SHA_RND1(A,B,C,D,E, 3);

  SHA_MIX( 4,  1, 12,  6); SHA_RND2(E,A,B,C,D, 4);

  SHA_MIX( 5,  2, 13,  7); SHA_RND2(D,E,A,B,C, 5);

  SHA_MIX( 6,  3, 14,  8); SHA_RND2(C,D,E,A,B, 6);

  SHA_MIX( 7,  4, 15,  9); SHA_RND2(B,C,D,E,A, 7);

  SHA_MIX( 8,  5,  0, 10); SHA_RND2(A,B,C,D,E, 8);

  SHA_MIX( 9,  6,  1, 11); SHA_RND2(E,A,B,C,D, 9);

  SHA_MIX(10,  7,  2, 12); SHA_RND2(D,E,A,B,C,10);

  SHA_MIX(11,  8,  3, 13); SHA_RND2(C,D,E,A,B,11);

  SHA_MIX(12,  9,  4, 14); SHA_RND2(B,C,D,E,A,12);

  SHA_MIX(13, 10,  5, 15); SHA_RND2(A,B,C,D,E,13);

  SHA_MIX(14, 11,  6,  0); SHA_RND2(E,A,B,C,D,14);

  SHA_MIX(15, 12,  7,  1); SHA_RND2(D,E,A,B,C,15);

  SHA_MIX( 0, 13,  8,  2); SHA_RND2(C,D,E,A,B, 0);

  SHA_MIX( 1, 14,  9,  3); SHA_RND2(B,C,D,E,A, 1);

  SHA_MIX( 2, 15, 10,  4); SHA_RND2(A,B,C,D,E, 2);

  SHA_MIX( 3,  0, 11,  5); SHA_RND2(E,A,B,C,D, 3);

  SHA_MIX( 4,  1, 12,  6); SHA_RND2(D,E,A,B,C, 4);

  SHA_MIX( 5,  2, 13,  7); SHA_RND2(C,D,E,A,B, 5);

  SHA_MIX( 6,  3, 14,  8); SHA_RND2(B,C,D,E,A, 6);

  SHA_MIX( 7,  4, 15,  9); SHA_RND2(A,B,C,D,E, 7);

  SHA_MIX( 8,  5,  0, 10); SHA_RND3(E,A,B,C,D, 8);

  SHA_MIX( 9,  6,  1, 11); SHA_RND3(D,E,A,B,C, 9);

  SHA_MIX(10,  7,  2, 12); SHA_RND3(C,D,E,A,B,10);

  SHA_MIX(11,  8,  3, 13); SHA_RND3(B,C,D,E,A,11);

  SHA_MIX(12,  9,  4, 14); SHA_RND3(A,B,C,D,E,12);

  SHA_MIX(13, 10,  5, 15); SHA_RND3(E,A,B,C,D,13);

  SHA_MIX(14, 11,  6,  0); SHA_RND3(D,E,A,B,C,14);

  SHA_MIX(15, 12,  7,  1); SHA_RND3(C,D,E,A,B,15);

  SHA_MIX( 0, 13,  8,  2); SHA_RND3(B,C,D,E,A, 0);

  SHA_MIX( 1, 14,  9,  3); SHA_RND3(A,B,C,D,E, 1);

  SHA_MIX( 2, 15, 10,  4); SHA_RND3(E,A,B,C,D, 2);

  SHA_MIX( 3,  0, 11,  5); SHA_RND3(D,E,A,B,C, 3);

  SHA_MIX( 4,  1, 12,  6); SHA_RND3(C,D,E,A,B, 4);

  SHA_MIX( 5,  2, 13,  7); SHA_RND3(B,C,D,E,A, 5);

  SHA_MIX( 6,  3, 14,  8); SHA_RND3(A,B,C,D,E, 6);

  SHA_MIX( 7,  4, 15,  9); SHA_RND3(E,A,B,C,D, 7);

  SHA_MIX( 8,  5,  0, 10); SHA_RND3(D,E,A,B,C, 8);

  SHA_MIX( 9,  6,  1, 11); SHA_RND3(C,D,E,A,B, 9);

  SHA_MIX(10,  7,  2, 12); SHA_RND3(B,C,D,E,A,10);

  SHA_MIX(11,  8,  3, 13); SHA_RND3(A,B,C,D,E,11);

  SHA_MIX(12,  9,  4, 14); SHA_RND4(E,A,B,C,D,12);

  SHA_MIX(13, 10,  5, 15); SHA_RND4(D,E,A,B,C,13);

  SHA_MIX(14, 11,  6,  0); SHA_RND4(C,D,E,A,B,14);

  SHA_MIX(15, 12,  7,  1); SHA_RND4(B,C,D,E,A,15);

  SHA_MIX( 0, 13,  8,  2); SHA_RND4(A,B,C,D,E, 0);

  SHA_MIX( 1, 14,  9,  3); SHA_RND4(E,A,B,C,D, 1);

  SHA_MIX( 2, 15, 10,  4); SHA_RND4(D,E,A,B,C, 2);

  SHA_MIX( 3,  0, 11,  5); SHA_RND4(C,D,E,A,B, 3);

  SHA_MIX( 4,  1, 12,  6); SHA_RND4(B,C,D,E,A, 4);

  SHA_MIX( 5,  2, 13,  7); SHA_RND4(A,B,C,D,E, 5);

  SHA_MIX( 6,  3, 14,  8); SHA_RND4(E,A,B,C,D, 6);

  SHA_MIX( 7,  4, 15,  9); SHA_RND4(D,E,A,B,C, 7);

  SHA_MIX( 8,  5,  0, 10); SHA_RND4(C,D,E,A,B, 8);

  SHA_MIX( 9,  6,  1, 11); SHA_RND4(B,C,D,E,A, 9);

  SHA_MIX(10,  7,  2, 12); SHA_RND4(A,B,C,D,E,10);

  SHA_MIX(11,  8,  3, 13); SHA_RND4(E,A,B,C,D,11);

  SHA_MIX(12,  9,  4, 14); SHA_RND4(D,E,A,B,C,12);

  SHA_MIX(13, 10,  5, 15); SHA_RND4(C,D,E,A,B,13);

  SHA_MIX(14, 11,  6,  0); SHA_RND4(B,C,D,E,A,14);

  SHA_MIX(15, 12,  7,  1); SHA_RND4(A,B,C,D,E,15);

  XH(0) += A;

  XH(1) += B;

  XH(2) += C;

  XH(3) += D;

  XH(4) += E;

}