Reland "Cut down /crypto and switch what is left of it to boringssl".

crypto/ghash.cc

Index: crypto/ghash.cc
diff --git a/crypto/ghash.cc b/crypto/ghash.cc
deleted file mode 100644
index 1acd474cbc69a9c066b09f4655ab1d393b14f674..0000000000000000000000000000000000000000
--- a/crypto/ghash.cc
+++ /dev/null
@@ -1,259 +0,0 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "crypto/ghash.h"
-
-#include <algorithm>
-
-#include "base/logging.h"
-#include "base/sys_byteorder.h"
-
-namespace crypto {
-
-// GaloisHash is a polynomial authenticator that works in GF(2^128).
-//
-// Elements of the field are represented in `little-endian' order (which
-// matches the description in the paper[1]), thus the most significant bit is
-// the right-most bit. (This is backwards from the way that everybody else does
-// it.)
-//
-// We store field elements in a pair of such `little-endian' uint64s. So the
-// value one is represented by {low = 2**63, high = 0} and doubling a value
-// involves a *right* shift.
-//
-// [1] http://csrc.nist.gov/groups/ST/toolkit/BCM/documents/proposedmodes/gcm/gcm-revised-spec.pdf
-
-namespace {
-
-// Get64 reads a 64-bit, big-endian number from |bytes|.
-uint64 Get64(const uint8 bytes[8]) {
-  uint64 t;
-  memcpy(&t, bytes, sizeof(t));
-  return base::NetToHost64(t);
-}
-
-// Put64 writes |x| to |bytes| as a 64-bit, big-endian number.
-void Put64(uint8 bytes[8], uint64 x) {
-  x = base::HostToNet64(x);
-  memcpy(bytes, &x, sizeof(x));
-}
-
-// Reverse reverses the order of the bits of 4-bit number in |i|.
-int Reverse(int i) {
-  i = ((i << 2) & 0xc) | ((i >> 2) & 0x3);
-  i = ((i << 1) & 0xa) | ((i >> 1) & 0x5);
-  return i;
-}
-
-}  // namespace
-
-GaloisHash::GaloisHash(const uint8 key[16]) {
-  Reset();
-
-  // We precompute 16 multiples of |key|. However, when we do lookups into this
-  // table we'll be using bits from a field element and therefore the bits will
-  // be in the reverse order. So normally one would expect, say, 4*key to be in
-  // index 4 of the table but due to this bit ordering it will actually be in
-  // index 0010 (base 2) = 2.
-  FieldElement x = {Get64(key), Get64(key+8)};
-  product_table_[0].low = 0;
-  product_table_[0].hi = 0;
-  product_table_[Reverse(1)] = x;
-
-  for (int i = 0; i < 16; i += 2) {
-    product_table_[Reverse(i)] = Double(product_table_[Reverse(i/2)]);
-    product_table_[Reverse(i+1)] = Add(product_table_[Reverse(i)], x);
-  }
-}
-
-void GaloisHash::Reset() {
-  state_ = kHashingAdditionalData;
-  additional_bytes_ = 0;
-  ciphertext_bytes_ = 0;
-  buf_used_ = 0;
-  y_.low = 0;
-  y_.hi = 0;
-}
-
-void GaloisHash::UpdateAdditional(const uint8* data, size_t length) {
-  DCHECK_EQ(state_, kHashingAdditionalData);
-  additional_bytes_ += length;
-  Update(data, length);
-}
-
-void GaloisHash::UpdateCiphertext(const uint8* data, size_t length) {
-  if (state_ == kHashingAdditionalData) {
-    // If there's any remaining additional data it's zero padded to the next
-    // full block.
-    if (buf_used_ > 0) {
-      memset(&buf_[buf_used_], 0, sizeof(buf_)-buf_used_);
-      UpdateBlocks(buf_, 1);
-      buf_used_ = 0;
-    }
-    state_ = kHashingCiphertext;
-  }
-
-  DCHECK_EQ(state_, kHashingCiphertext);
-  ciphertext_bytes_ += length;
-  Update(data, length);
-}
-
-void GaloisHash::Finish(void* output, size_t len) {
-  DCHECK(state_ != kComplete);
-
-  if (buf_used_ > 0) {
-    // If there's any remaining data (additional data or ciphertext), it's zero
-    // padded to the next full block.
-    memset(&buf_[buf_used_], 0, sizeof(buf_)-buf_used_);
-    UpdateBlocks(buf_, 1);
-    buf_used_ = 0;
-  }
-
-  state_ = kComplete;
-
-  // The lengths of the additional data and ciphertext are included as the last
-  // block. The lengths are the number of bits.
-  y_.low ^= additional_bytes_*8;
-  y_.hi ^= ciphertext_bytes_*8;
-  MulAfterPrecomputation(product_table_, &y_);
-
-  uint8 *result, result_tmp[16];
-  if (len >= 16) {
-    result = reinterpret_cast<uint8*>(output);
-  } else {
-    result = result_tmp;
-  }
-
-  Put64(result, y_.low);
-  Put64(result + 8, y_.hi);
-
-  if (len < 16)
-    memcpy(output, result_tmp, len);
-}
-
-// static
-GaloisHash::FieldElement GaloisHash::Add(
-    const FieldElement& x,
-    const FieldElement& y) {
-  // Addition in a characteristic 2 field is just XOR.
-  FieldElement z = {x.low^y.low, x.hi^y.hi};
-  return z;
-}
-
-// static
-GaloisHash::FieldElement GaloisHash::Double(const FieldElement& x) {
-  const bool msb_set = x.hi & 1;
-
-  FieldElement xx;
-  // Because of the bit-ordering, doubling is actually a right shift.
-  xx.hi = x.hi >> 1;
-  xx.hi |= x.low << 63;
-  xx.low = x.low >> 1;
-
-  // If the most-significant bit was set before shifting then it, conceptually,
-  // becomes a term of x^128. This is greater than the irreducible polynomial
-  // so the result has to be reduced. The irreducible polynomial is
-  // 1+x+x^2+x^7+x^128. We can subtract that to eliminate the term at x^128
-  // which also means subtracting the other four terms. In characteristic 2
-  // fields, subtraction == addition == XOR.
-  if (msb_set)
-    xx.low ^= 0xe100000000000000ULL;
-
-  return xx;
-}
-
-void GaloisHash::MulAfterPrecomputation(const FieldElement* table,
-                                        FieldElement* x) {
-  FieldElement z = {0, 0};
-
-  // In order to efficiently multiply, we use the precomputed table of i*key,
-  // for i in 0..15, to handle four bits at a time. We could obviously use
-  // larger tables for greater speedups but the next convenient table size is
-  // 4K, which is a little large.
-  //
-  // In other fields one would use bit positions spread out across the field in
-  // order to reduce the number of doublings required. However, in
-  // characteristic 2 fields, repeated doublings are exceptionally cheap and
-  // it's not worth spending more precomputation time to eliminate them.
-  for (unsigned i = 0; i < 2; i++) {
-    uint64 word;
-    if (i == 0) {
-      word = x->hi;
-    } else {
-      word = x->low;
-    }
-
-    for (unsigned j = 0; j < 64; j += 4) {
-      Mul16(&z);
-      // the values in |table| are ordered for little-endian bit positions. See
-      // the comment in the constructor.
-      const FieldElement& t = table[word & 0xf];
-      z.low ^= t.low;
-      z.hi ^= t.hi;
-      word >>= 4;
-    }
-  }
-
-  *x = z;
-}
-
-// kReductionTable allows for rapid multiplications by 16. A multiplication by
-// 16 is a right shift by four bits, which results in four bits at 2**128.
-// These terms have to be eliminated by dividing by the irreducible polynomial.
-// In GHASH, the polynomial is such that all the terms occur in the
-// least-significant 8 bits, save for the term at x^128. Therefore we can
-// precompute the value to be added to the field element for each of the 16 bit
-// patterns at 2**128 and the values fit within 12 bits.
-static const uint16 kReductionTable[16] = {
-  0x0000, 0x1c20, 0x3840, 0x2460, 0x7080, 0x6ca0, 0x48c0, 0x54e0,
-  0xe100, 0xfd20, 0xd940, 0xc560, 0x9180, 0x8da0, 0xa9c0, 0xb5e0,
-};
-
-// static
-void GaloisHash::Mul16(FieldElement* x) {
-  const unsigned msw = x->hi & 0xf;
-  x->hi >>= 4;
-  x->hi |= x->low << 60;
-  x->low >>= 4;
-  x->low ^= static_cast<uint64>(kReductionTable[msw]) << 48;
-}
-
-void GaloisHash::UpdateBlocks(const uint8* bytes, size_t num_blocks) {
-  for (size_t i = 0; i < num_blocks; i++) {
-    y_.low ^= Get64(bytes);
-    bytes += 8;
-    y_.hi ^= Get64(bytes);
-    bytes += 8;
-    MulAfterPrecomputation(product_table_, &y_);
-  }
-}
-
-void GaloisHash::Update(const uint8* data, size_t length) {
-  if (buf_used_ > 0) {
-    const size_t n = std::min(length, sizeof(buf_) - buf_used_);
-    memcpy(&buf_[buf_used_], data, n);
-    buf_used_ += n;
-    length -= n;
-    data += n;
-
-    if (buf_used_ == sizeof(buf_)) {
-      UpdateBlocks(buf_, 1);
-      buf_used_ = 0;
-    }
-  }
-
-  if (length >= 16) {
-    const size_t n = length / 16;
-    UpdateBlocks(data, n);
-    length -= n*16;
-    data += n*16;
-  }
-
-  if (length > 0) {
-    memcpy(buf_, data, length);
-    buf_used_ = length;
-  }
-}
-
-}  // namespace crypto