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diff --git a/base/sha1.cc b/base/sha1.cc
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+++ b/base/sha1.cc
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+// Copyright (c) 2009 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 "base/sha1.h"
+
+#include "base/basictypes.h"
+
+namespace base {
+
+// Implementation of SHA-1. Only handles data in byte-sized blocks,
+// which simplifies the code a fair bit.
+
+// This file also contains an HMAC implementation using SHA-1
+
+// Identifier names follow notation in FIPS PUB 180-3, where you'll
+// also find a description of the algorithm:
+// http://csrc.nist.gov/publications/fips/fips180-3/fips180-3_final.pdf
+
+// Usage example:
+//
+// SecureHashAlgorithm sha;
+// while(there is data to hash)
+//   sha.Update(moredata, size of data);
+// sha.Final();
+// memcpy(somewhere, sha.Digest(), 20);
+//
+// to reuse the instance of sha, call sha.Init();
+
+// TODO(jhawkins): Replace this implementation with a per-platform
+// implementation using each platform's crypto library.
+
+class SecureHashAlgorithm {
+ public:
+  SecureHashAlgorithm() { Init(); }
+
+  static const int kDigestSizeBytes;
+
+  void Init();
+  void Update(const void* data, size_t nbytes);
+  void Final();
+
+  // 20 bytes of message digest.
+  const unsigned char* Digest() const {
+    return reinterpret_cast<const unsigned char*>(H);
+  }
+
+ private:
+  void Pad();
+  void Process();
+
+  uint32 A, B, C, D, E;
+
+  uint32 H[5];
+
+  union {
+    uint32 W[80];
+    uint8 M[64];
+  };
+
+  uint32 cursor;
+  uint32 l;
+};
+
+static inline uint32 f(uint32 t, uint32 B, uint32 C, uint32 D) {
+  if (t < 20) {
+    return (B & C) | ((~B) & D);
+  } else if (t < 40) {
+    return B ^ C ^ D;
+  } else if (t < 60) {
+    return (B & C) | (B & D) | (C & D);
+  } else {
+    return B ^ C ^ D;
+  }
+}
+
+static inline uint32 S(uint32 n, uint32 X) {
+  return (X << n) | (X >> (32-n));
+}
+
+static inline uint32 K(uint32 t) {
+  if (t < 20) {
+    return 0x5a827999;
+  } else if (t < 40) {
+    return 0x6ed9eba1;
+  } else if (t < 60) {
+    return 0x8f1bbcdc;
+  } else {
+    return 0xca62c1d6;
+  }
+}
+
+static inline void swapends(uint32& t) {
+  t = ((t & 0xff000000) >> 24) |
+      ((t & 0xff0000) >> 8) |
+      ((t & 0xff00) << 8) |
+      ((t & 0xff) << 24);
+}
+
+const int SecureHashAlgorithm::kDigestSizeBytes = 20;
+
+void SecureHashAlgorithm::Init() {
+  cursor = 0;
+  l = 0;
+  H[0] = 0x67452301;
+  H[1] = 0xefcdab89;
+  H[2] = 0x98badcfe;
+  H[3] = 0x10325476;
+  H[4] = 0xc3d2e1f0;
+}
+
+void SecureHashAlgorithm::Final() {
+  Pad();
+  Process();
+
+  for (int t = 0; t < 5; ++t)
+    swapends(H[t]);
+}
+
+void SecureHashAlgorithm::Update(const void* data, size_t nbytes) {
+  const uint8* d = reinterpret_cast<const uint8*>(data);
+  while (nbytes--) {
+    M[cursor++] = *d++;
+    if (cursor >= 64)
+      Process();
+    l += 8;
+  }
+}
+
+void SecureHashAlgorithm::Pad() {
+  M[cursor++] = 0x80;
+
+  if (cursor > 64-8) {
+    // pad out to next block
+    while (cursor < 64)
+      M[cursor++] = 0;
+
+    Process();
+  }
+
+  while (cursor < 64-4)
+    M[cursor++] = 0;
+
+  M[64-4] = (l & 0xff000000) >> 24;
+  M[64-3] = (l & 0xff0000) >> 16;
+  M[64-2] = (l & 0xff00) >> 8;
+  M[64-1] = (l & 0xff);
+}
+
+void SecureHashAlgorithm::Process() {
+  uint32 t;
+
+  // Each a...e corresponds to a section in the FIPS 180-3 algorithm.
+
+  // a.
+  //
+  // W and M are in a union, so no need to memcpy.
+  // memcpy(W, M, sizeof(M));
+  for (t = 0; t < 16; ++t)
+    swapends(W[t]);
+
+  // b.
+  for (t = 16; t < 80; ++t)
+    W[t] = S(1, W[t - 3] ^ W[t - 8] ^ W[t - 14] ^ W[t - 16]);
+
+  // c.
+  A = H[0];
+  B = H[1];
+  C = H[2];
+  D = H[3];
+  E = H[4];
+
+  // d.
+  for (t = 0; t < 80; ++t) {
+    uint32 TEMP = S(5, A) + f(t, B, C, D) + E + W[t] + K(t);
+    E = D;
+    D = C;
+    C = S(30, B);
+    B = A;
+    A = TEMP;
+  }
+
+  // e.
+  H[0] += A;
+  H[1] += B;
+  H[2] += C;
+  H[3] += D;
+  H[4] += E;
+
+  cursor = 0;
+}
+
+std::string SHA1HashString(const std::string& str) {
+  SecureHashAlgorithm sha;
+  sha.Update(str.c_str(), str.length());
+  sha.Final();
+  std::string out(reinterpret_cast<const char*>(sha.Digest()),
+                  SecureHashAlgorithm::kDigestSizeBytes);
+  return out;
+}
+
+}  // namespace base