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 /* 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/Endian.h"

 #include "mozilla/SHA1.h"

 #include <string.h>

 using mozilla::NativeEndian;

 using mozilla::SHA1Sum;

 static inline uint32_t

 SHA_ROTL(uint32_t t, uint32_t n)

 {

   MOZ_ASSERT(n < 32);

   return (t << n) | (t >> (32 - n));

 }

 static void

 shaCompress(volatile unsigned* X, const uint32_t* datain);

 #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()

   : size(0), mDone(false)

 {

   // Initialize H with constants from FIPS180-1.

   H[0] = 0x67452301L;

   H[1] = 0xefcdab89L;

   H[2] = 0x98badcfeL;

   H[3] = 0x10325476L;

   H[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* dataIn, uint32_t len)

 {

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

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

   if (len == 0)

     return;

   /* Accumulate the byte count. */

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

   size += len;

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

   unsigned int togo;

   if (lenB > 0) {

     togo = 64U - lenB;

     if (len < togo)

       togo = len;

     memcpy(u.b + lenB, data, togo);

     len -= togo;

     data += togo;

     lenB = (lenB + togo) & 63U;

     if (!lenB)

       shaCompress(&H[H2X], u.w);

   }

   while (len >= 64U) {

     len -= 64U;

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

     data += 64U;

   }

   if (len > 0)

     memcpy(u.b, data, len);

 }

 /*

  *  SHA: Generate hash value

  */

 void

 SHA1Sum::finish(SHA1Sum::Hash& hashOut)

 {

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

   uint64_t size2 = size;

   uint32_t lenB = uint32_t(size2) & 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(size) & 63) == 56);

   /* Convert size from bytes to bits. */

   size2 <<= 3;

   u.w[14] = NativeEndian::swapToBigEndian(uint32_t(size2 >> 32));

   u.w[15] = NativeEndian::swapToBigEndian(uint32_t(size2));

   shaCompress(&H[H2X], u.w);

   /* Output hash. */

   u.w[0] = NativeEndian::swapToBigEndian(H[0]);

   u.w[1] = NativeEndian::swapToBigEndian(H[1]);

   u.w[2] = NativeEndian::swapToBigEndian(H[2]);

   u.w[3] = NativeEndian::swapToBigEndian(H[3]);

   u.w[4] = NativeEndian::swapToBigEndian(H[4]);

   memcpy(hashOut, u.w, 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 *X, const uint32_t *inbuf)

 {

   unsigned A, B, C, D, E;

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

 #define XW(n) X[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(inbuf[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;

 }