From 9c8593d2b4e25ef628172ceadbedf0ef078d01ef Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Mon, 27 Jun 2016 16:06:17 +0200
Subject: [PATCH] Implement SipHash in Python

---
 qa/rpc-tests/test_framework/siphash.py | 64 ++++++++++++++++++++++++++
 src/test/hash_tests.cpp                |  4 ++
 2 files changed, 68 insertions(+)
 create mode 100644 qa/rpc-tests/test_framework/siphash.py

diff --git a/qa/rpc-tests/test_framework/siphash.py b/qa/rpc-tests/test_framework/siphash.py
new file mode 100644
index 000000000..9c0574bd9
--- /dev/null
+++ b/qa/rpc-tests/test_framework/siphash.py
@@ -0,0 +1,64 @@
+#!/usr/bin/env python3
+# Copyright (c) 2016 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#
+# siphash.py - Specialized SipHash-2-4 implementations
+#
+# This implements SipHash-2-4 for 256-bit integers.
+
+def rotl64(n, b):
+    return n >> (64 - b) | (n & ((1 << (64 - b)) - 1)) << b
+
+def siphash_round(v0, v1, v2, v3):
+    v0 = (v0 + v1) & ((1 << 64) - 1)
+    v1 = rotl64(v1, 13)
+    v1 ^= v0
+    v0 = rotl64(v0, 32)
+    v2 = (v2 + v3) & ((1 << 64) - 1)
+    v3 = rotl64(v3, 16)
+    v3 ^= v2
+    v0 = (v0 + v3) & ((1 << 64) - 1)
+    v3 = rotl64(v3, 21)
+    v3 ^= v0
+    v2 = (v2 + v1) & ((1 << 64) - 1)
+    v1 = rotl64(v1, 17)
+    v1 ^= v2
+    v2 = rotl64(v2, 32)
+    return (v0, v1, v2, v3)
+
+def siphash256(k0, k1, h):
+    n0 = h & ((1 << 64) - 1)
+    n1 = (h >> 64) & ((1 << 64) - 1)
+    n2 = (h >> 128) & ((1 << 64) - 1)
+    n3 = (h >> 192) & ((1 << 64) - 1)
+    v0 = 0x736f6d6570736575 ^ k0
+    v1 = 0x646f72616e646f6d ^ k1
+    v2 = 0x6c7967656e657261 ^ k0
+    v3 = 0x7465646279746573 ^ k1 ^ n0
+    v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
+    v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
+    v0 ^= n0
+    v3 ^= n1
+    v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
+    v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
+    v0 ^= n1
+    v3 ^= n2
+    v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
+    v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
+    v0 ^= n2
+    v3 ^= n3
+    v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
+    v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
+    v0 ^= n3
+    v3 ^= 0x2000000000000000
+    v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
+    v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
+    v0 ^= 0x2000000000000000
+    v2 ^= 0xFF
+    v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
+    v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
+    v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
+    v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
+    return v0 ^ v1 ^ v2 ^ v3
diff --git a/src/test/hash_tests.cpp b/src/test/hash_tests.cpp
index 82d61209b..fa9624f13 100644
--- a/src/test/hash_tests.cpp
+++ b/src/test/hash_tests.cpp
@@ -122,6 +122,10 @@ BOOST_AUTO_TEST_CASE(siphash)
         hasher3.Write(uint64_t(x)|(uint64_t(x+1)<<8)|(uint64_t(x+2)<<16)|(uint64_t(x+3)<<24)|
                      (uint64_t(x+4)<<32)|(uint64_t(x+5)<<40)|(uint64_t(x+6)<<48)|(uint64_t(x+7)<<56));
     }
+
+    CHashWriter ss(SER_DISK, CLIENT_VERSION);
+    ss << CTransaction();
+    BOOST_CHECK_EQUAL(SipHashUint256(1, 2, ss.GetHash()), 0x79751e980c2a0a35ULL);
 }
 
 BOOST_AUTO_TEST_SUITE_END()