1 files changed, 223 insertions, 0 deletions
diff --git a/internal/xmpmeta/md5.cc b/internal/xmpmeta/md5.cc
new file mode 100644
index 0000000..1349483
--- /dev/null
+++ b/internal/xmpmeta/md5.cc
@@ -0,0 +1,223 @@
+#include "xmpmeta/md5.h"
+
+#include <string.h>  // for memcpy().
+
+#include <vector>
+
+#include "base/integral_types.h"
+#include "strings/escaping.h"
+
+namespace photos_editing_formats {
+namespace {
+
+const int kMd5DigestSize = 16;
+
+typedef struct MD5Context MD5_CTX;
+
+struct MD5Context {
+  uint32 buf[4];
+  uint32 bits[2];
+  uint32 in[16];
+};
+
+void MD5Init(struct MD5Context* context);
+void MD5Update(struct MD5Context* context, const uint8* data, size_t len);
+void MD5Final(unsigned char digest[16], struct MD5Context* ctx);
+void MD5Transform(uint32 buf[4], const uint32 in[16]);
+
+// Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
+// initialization constants.
+void MD5Init(MD5Context* context) {
+  context->buf[0] = 0x67452301;
+  context->buf[1] = 0xefcdab89;
+  context->buf[2] = 0x98badcfe;
+  context->buf[3] = 0x10325476;
+  context->bits[0] = 0;
+  context->bits[1] = 0;
+}
+
+// Update context to reflect the concatenation of another buffer full of bytes.
+void MD5Update(MD5Context* context, const uint8* data, size_t len) {
+  // Update bitcount.
+  uint32 t = context->bits[0];
+  if ((context->bits[0] = t + (static_cast<uint32>(len) << 3)) < t) {
+    context->bits[1]++;  // Carry from low to high.
+  }
+  context->bits[1] += len >> 29;
+  t = (t >> 3) & 0x3f;  // Bytes already in shsInfo->data.
+
+  // Handle any leading odd-sized chunks.
+  if (t) {
+    uint8* p = reinterpret_cast<uint8*>(context->in) + t;
+
+    t = 64 - t;
+    if (len < t) {
+      memcpy(p, data, len);
+      return;
+    }
+    memcpy(p, data, t);
+    MD5Transform(context->buf, context->in);
+    data += t;
+    len -= t;
+  }
+
+  // Process data in 64-byte chunks.
+  while (len >= 64) {
+    memcpy(context->in, data, 64);
+    MD5Transform(context->buf, context->in);
+    data += 64;
+    len -= 64;
+  }
+
+  // Handle any remaining bytes of data.
+  memcpy(context->in, data, len);
+}
+
+// Final wrapup - pad to 64-byte boundary with the bit pattern.
+// 1 0* (64-bit count of bits processed, MSB-first)
+void MD5Final(uint8 digest[16], MD5Context* ctx) {
+  // Compute number of bytes mod 64.
+  uint32 count = (ctx->bits[0] >> 3) & 0x3F;
+
+  // Set the first char of padding to 0x80.  This is safe since there is
+  // always at least one byte free.
+  uint8* p = reinterpret_cast<uint8*>(ctx->in) + count;
+  *p++ = 0x80;
+
+  // Bytes of padding needed to make 64 bytes.
+  count = 64 - 1 - count;
+
+  // Pad out to 56 mod 64.
+  if (count < 8) {
+    // Two lots of padding:  Pad the first block to 64 bytes.
+    memset(p, 0, count);
+    MD5Transform(ctx->buf, ctx->in);
+
+    // Now fill the next block with 56 bytes.
+    memset(ctx->in, 0, 56);
+  } else {
+    // Pad block to 56 bytes.
+    memset(p, 0, count - 8);
+  }
+
+  // Append length in bits and transform.
+  ctx->in[14] = ctx->bits[0];
+  ctx->in[15] = ctx->bits[1];
+
+  MD5Transform(ctx->buf, ctx->in);
+  memcpy(digest, ctx->buf, 16);
+  memset(ctx, 0, sizeof(*ctx));  // In case it's sensitive.
+}
+
+// The four core functions - F1 is optimized somewhat.
+// #define F1(x, y, z) (x & y | ~x & z)
+#define F1(x, y, z) (z ^ (x & (y ^ z)))
+#define F2(x, y, z) F1(z, x, y)
+#define F3(x, y, z) (x ^ y ^ z)
+#define F4(x, y, z) (y ^ (x | ~z))
+
+// This is the central step in the MD5 algorithm.
+#define MD5STEP(f, w, x, y, z, data, s) \
+  (w += f(x, y, z) + data, w = w << s | w >> (32 - s), w += x)
+
+// The core of the MD5 algorithm, this alters an existing MD5 hash to
+// reflect the addition of 16 longwords of new data.  MD5Update blocks
+// the data and converts bytes into longwords for this routine.
+void MD5Transform(uint32 buf[4], const uint32 in[16]) {
+  uint32 a = buf[0];
+  uint32 b = buf[1];
+  uint32 c = buf[2];
+  uint32 d = buf[3];
+
+  MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
+  MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
+  MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
+  MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
+  MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
+  MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
+  MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
+  MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
+  MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
+  MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
+  MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
+  MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
+  MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
+  MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
+  MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
+  MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);
+
+  MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
+  MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
+  MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
+  MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
+  MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
+  MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
+  MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
+  MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
+  MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
+  MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
+  MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
+  MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
+  MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
+  MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
+  MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
+  MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);
+
+  MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
+  MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
+  MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
+  MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
+  MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
+  MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
+  MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
+  MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
+  MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
+  MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
+  MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
+  MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
+  MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
+  MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
+  MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
+  MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);
+
+  MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
+  MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
+  MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
+  MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
+  MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
+  MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
+  MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
+  MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
+  MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
+  MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
+  MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
+  MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
+  MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
+  MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
+  MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
+  MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);
+  buf[0] += a;
+  buf[1] += b;
+  buf[2] += c;
+  buf[3] += d;
+}
+
+void MD5(const uint8_t* to_hash, size_t to_hash_length, uint8_t* output) {
+  MD5Context md5_context;
+  MD5Init(&md5_context);
+  MD5Update(&md5_context, to_hash, to_hash_length);
+  MD5Final(output, &md5_context);
+}
+
+}  // namespace
+
+string MD5Hash(const string& to_hash) {
+  std::vector<uint8_t> buffer;
+  buffer.resize(kMd5DigestSize);
+  MD5(reinterpret_cast<const uint8_t*>(to_hash.data()), to_hash.length(),
+      &buffer[0]);
+  return dynamic_depth::strings::b2a_hex(
+      reinterpret_cast<const char*>(&buffer[0]), kMd5DigestSize);
+}
+
+}  // namespace photos_editing_formats