1 files changed, 129 insertions, 2 deletions
diff --git a/src/lib/mac/poly1305/poly1305.cpp b/src/lib/mac/poly1305/poly1305.cpp
index 8cf42abbb..5241afcd7 100644
--- a/src/lib/mac/poly1305/poly1305.cpp
+++ b/src/lib/mac/poly1305/poly1305.cpp
@@ -1,5 +1,8 @@
 /*
-* Poly1305
+* Derived from poly1305-donna-64.h by Andrew Moon <[email protected]>
+* in https://github.com/floodyberry/poly1305-donna
+*
+* (C) 2014 Andrew Moon
 * (C) 2014 Jack Lloyd
 *
 * Botan is released under the Simplified BSD License (see license.txt)
@@ -7,12 +10,136 @@
 
 #include <botan/internal/mac_utils.h>
 #include <botan/poly1305.h>
-#include <botan/internal/poly1305_donna.h>
+#include <botan/loadstor.h>
+#include <botan/mul128.h>
+#include <botan/internal/donna128.h>
 
 namespace Botan {
 
 BOTAN_REGISTER_MAC_NOARGS(Poly1305);
 
+namespace {
+
+void poly1305_init(secure_vector<u64bit>& X, const byte key[32])
+   {
+   /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
+   const u64bit t0 = load_le<u64bit>(key, 0);
+   const u64bit t1 = load_le<u64bit>(key, 1);
+
+   X[0] = ( t0                    ) & 0xffc0fffffff;
+   X[1] = ((t0 >> 44) | (t1 << 20)) & 0xfffffc0ffff;
+   X[2] = ((t1 >> 24)             ) & 0x00ffffffc0f;
+
+   /* h = 0 */
+   X[3] = 0;
+   X[4] = 0;
+   X[5] = 0;
+
+   /* save pad for later */
+   X[6] = load_le<u64bit>(key, 2);
+   X[7] = load_le<u64bit>(key, 3);
+   }
+
+void poly1305_blocks(secure_vector<u64bit>& X, const byte *m, size_t blocks, bool is_final = false)
+   {
+#if !defined(BOTAN_TARGET_HAS_NATIVE_UINT128)
+   typedef donna128 uint128_t;
+#endif
+
+   const u64bit hibit = is_final ? 0 : (static_cast<u64bit>(1) << 40); /* 1 << 128 */
+
+   const u64bit r0 = X[0];
+   const u64bit r1 = X[1];
+   const u64bit r2 = X[2];
+
+   u64bit h0 = X[3+0];
+   u64bit h1 = X[3+1];
+   u64bit h2 = X[3+2];
+
+   const u64bit s1 = r1 * (5 << 2);
+   const u64bit s2 = r2 * (5 << 2);
+
+   while(blocks--)
+      {
+      /* h += m[i] */
+      const u64bit t0 = load_le<u64bit>(m, 0);
+      const u64bit t1 = load_le<u64bit>(m, 1);
+
+      h0 += (( t0                    ) & 0xfffffffffff);
+      h1 += (((t0 >> 44) | (t1 << 20)) & 0xfffffffffff);
+      h2 += (((t1 >> 24)             ) & 0x3ffffffffff) | hibit;
+
+      /* h *= r */
+      uint128_t d0 = uint128_t(h0) * r0 + uint128_t(h1) * s2 + uint128_t(h2) * s1;
+      uint128_t d1 = uint128_t(h0) * r1 + uint128_t(h1) * r0 + uint128_t(h2) * s2;
+      uint128_t d2 = uint128_t(h0) * r2 + uint128_t(h1) * r1 + uint128_t(h2) * r0;
+
+      /* (partial) h %= p */
+      u64bit        c = carry_shift(d0, 44); h0 = d0 & 0xfffffffffff;
+      d1 += c;      c = carry_shift(d1, 44); h1 = d1 & 0xfffffffffff;
+      d2 += c;      c = carry_shift(d2, 42); h2 = d2 & 0x3ffffffffff;
+      h0  += c * 5; c = carry_shift(h0, 44); h0 = h0 & 0xfffffffffff;
+      h1  += c;
+
+      m += 16;
+      }
+
+   X[3+0] = h0;
+   X[3+1] = h1;
+   X[3+2] = h2;
+   }
+
+void poly1305_finish(secure_vector<u64bit>& X, byte mac[16])
+   {
+   /* fully carry h */
+   u64bit h0 = X[3+0];
+   u64bit h1 = X[3+1];
+   u64bit h2 = X[3+2];
+
+   u64bit c;
+                c = (h1 >> 44); h1 &= 0xfffffffffff;
+   h2 += c;     c = (h2 >> 42); h2 &= 0x3ffffffffff;
+   h0 += c * 5; c = (h0 >> 44); h0 &= 0xfffffffffff;
+   h1 += c;     c = (h1 >> 44); h1 &= 0xfffffffffff;
+   h2 += c;     c = (h2 >> 42); h2 &= 0x3ffffffffff;
+   h0 += c * 5; c = (h0 >> 44); h0 &= 0xfffffffffff;
+   h1 += c;
+
+   /* compute h + -p */
+   u64bit g0 = h0 + 5; c = (g0 >> 44); g0 &= 0xfffffffffff;
+   u64bit g1 = h1 + c; c = (g1 >> 44); g1 &= 0xfffffffffff;
+   u64bit g2 = h2 + c - (static_cast<u64bit>(1) << 42);
+
+   /* select h if h < p, or h + -p if h >= p */
+   c = (g2 >> ((sizeof(u64bit) * 8) - 1)) - 1;
+   g0 &= c;
+   g1 &= c;
+   g2 &= c;
+   c = ~c;
+   h0 = (h0 & c) | g0;
+   h1 = (h1 & c) | g1;
+   h2 = (h2 & c) | g2;
+
+   /* h = (h + pad) */
+   const u64bit t0 = X[6];
+   const u64bit t1 = X[7];
+
+   h0 += (( t0                    ) & 0xfffffffffff)    ; c = (h0 >> 44); h0 &= 0xfffffffffff;
+   h1 += (((t0 >> 44) | (t1 << 20)) & 0xfffffffffff) + c; c = (h1 >> 44); h1 &= 0xfffffffffff;
+   h2 += (((t1 >> 24)             ) & 0x3ffffffffff) + c;                 h2 &= 0x3ffffffffff;
+
+   /* mac = h % (2^128) */
+   h0 = ((h0      ) | (h1 << 44));
+   h1 = ((h1 >> 20) | (h2 << 24));
+
+   store_le(&mac[0], h0, h1);
+
+   /* zero out the state */
+   zero_mem(&X[0], X.size());
+   }
+
+}
+
 void Poly1305::clear()
    {
    zap(m_poly);