Unordered: Initial stab at siphash example.

[SVN r81973]
2012-12-15 16:42:44 +00:00
parent 64994d76dd
commit bf1f24ab04
6 changed files with 413 additions and 0 deletions
@@ -0,0 +1,91 @@
+
+// Copyright 2012 Daniel James.
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// This is also released into the public domain.
+
+#include "siphash.hpp"
+
+namespace hash
+{
+    const unsigned siphash_c = 2;
+    const unsigned siphash_d = 4;
+
+    siphash_state::siphash_state(sipkey const& key) :
+        v0(0x736f6d6570736575ull ^ key.k0),
+        v1(0x646f72616e646f6dull ^ key.k1),
+        v2(0x6c7967656e657261ull ^ key.k0),
+        v3(0x7465646279746573ull ^ key.k1),
+        buffered(0), b(0)
+    {
+    }
+
+    namespace
+    {
+        inline boost::uint64_t rotate_left(boost::uint64_t x, unsigned c)
+        {
+            return (x << c) | (x >> (64-c));
+        }
+    }
+
+    void siphash_state::sip_round(unsigned rounds)
+    {
+        for (unsigned i = 0; i < rounds; ++i) {
+            v0 += v1;
+            v1 = rotate_left(v1, 13);
+            v1 ^= v0;
+            v0 = rotate_left(v0, 32);
+
+            v2 += v3;
+            v3 = rotate_left(v3, 16);
+            v3 ^= v2;
+
+            v2 += v1;
+            v1 = rotate_left(v1, 17);
+            v1 ^= v2;
+            v2 = rotate_left(v2, 32);
+
+            v0 += v3;
+            v3 = rotate_left(v3, 21);
+            v3 ^= v0;
+        }
+    }
+
+    void siphash_state::update(void const* data, unsigned length)
+    {
+        char const* ptr = static_cast<char const*>(data);
+
+        while (length > 0) {
+            buffer[buffered++] = *ptr++;
+            ++b;
+            --length;
+
+            if (buffered == 8)
+            {
+                v3 ^= m;
+                sip_round(siphash_c);
+                v0 ^= m;
+                buffered = 0;
+            }
+        }
+    }
+
+    boost::uint64_t siphash_state::finalize()
+    {
+        // Compress the final 8 bytes.
+        while (buffered < 7) buffer[buffered++] = 0;
+        buffer[7] = b;
+
+        v3 ^= m;
+        sip_round(siphash_c);
+        v0 ^= m;
+
+        // Finalize the hash
+
+        v2 ^= 0xff;
+        sip_round(siphash_d);
+
+        return v0 ^ v1 ^ v2 ^ v3;
+    }
+}