From 8466467a35e2b5ce14693103fd37bfe0ae67c3ce Mon Sep 17 00:00:00 2001
From: Sean Bowe <ewillbefull@gmail.com>
Date: Thu, 31 Mar 2016 14:23:56 -0600
Subject: [PATCH] Added SHA256Compress to Bitcoin's SHA256 implementation.

---
 src/Makefile.test.include         |  3 ++-
 src/crypto/sha256.cpp             | 10 +++++++++
 src/crypto/sha256.h               |  1 +
 src/test/sha256compress_tests.cpp | 35 +++++++++++++++++++++++++++++++
 4 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 src/test/sha256compress_tests.cpp

diff --git a/src/Makefile.test.include b/src/Makefile.test.include
index 825e7130d..e87b2238a 100644
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -76,7 +76,8 @@ BITCOIN_TESTS =\
   test/transaction_tests.cpp \
   test/uint256_tests.cpp \
   test/univalue_tests.cpp \
-  test/util_tests.cpp
+  test/util_tests.cpp \
+  test/sha256compress_tests.cpp
 
 if ENABLE_WALLET
 BITCOIN_TESTS += \
diff --git a/src/crypto/sha256.cpp b/src/crypto/sha256.cpp
index 5b9f00a0a..39583c26a 100644
--- a/src/crypto/sha256.cpp
+++ b/src/crypto/sha256.cpp
@@ -7,6 +7,7 @@
 #include "crypto/common.h"
 
 #include <string.h>
+#include <stdexcept>
 
 // Internal implementation code.
 namespace
@@ -171,6 +172,15 @@ void CSHA256::Finalize(unsigned char hash[OUTPUT_SIZE])
     WriteBE64(sizedesc, bytes << 3);
     Write(pad, 1 + ((119 - (bytes % 64)) % 64));
     Write(sizedesc, 8);
+    FinalizeNoPadding(hash, false);
+}
+
+void CSHA256::FinalizeNoPadding(unsigned char hash[OUTPUT_SIZE], bool enforce_compression)
+{
+    if (enforce_compression && bytes != 64) {
+        throw std::length_error("SHA256Compress should be invoked with a 512-bit block");
+    }
+
     WriteBE32(hash, s[0]);
     WriteBE32(hash + 4, s[1]);
     WriteBE32(hash + 8, s[2]);
diff --git a/src/crypto/sha256.h b/src/crypto/sha256.h
index 85cf33739..1c449b834 100644
--- a/src/crypto/sha256.h
+++ b/src/crypto/sha256.h
@@ -22,6 +22,7 @@ public:
     CSHA256();
     CSHA256& Write(const unsigned char* data, size_t len);
     void Finalize(unsigned char hash[OUTPUT_SIZE]);
+    void FinalizeNoPadding(unsigned char hash[OUTPUT_SIZE], bool enforce_compression = true);
     CSHA256& Reset();
 };
 
diff --git a/src/test/sha256compress_tests.cpp b/src/test/sha256compress_tests.cpp
new file mode 100644
index 000000000..aec36f073
--- /dev/null
+++ b/src/test/sha256compress_tests.cpp
@@ -0,0 +1,35 @@
+#include "test/test_bitcoin.h"
+#include "crypto/sha256.h"
+#include "uint256.h"
+
+#include <stdexcept>
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_FIXTURE_TEST_SUITE(sha256compress_tests, BasicTestingSetup)
+
+BOOST_AUTO_TEST_CASE(compression)
+{
+	{
+		unsigned char preimage[64] = {};
+		CSHA256 hasher;
+		hasher.Write(&preimage[0], 64);
+
+		uint256 digest;
+
+		hasher.FinalizeNoPadding(digest.begin());
+
+		BOOST_CHECK_MESSAGE(digest == uint256S("d8a93718eaf9feba4362d2c091d4e58ccabe9f779957336269b4b917be9856da"),
+			                digest.GetHex());
+	}
+
+	{
+		unsigned char preimage[63] = {};
+		CSHA256 hasher;
+		hasher.Write(&preimage[0], 63);
+		uint256 digest;
+		BOOST_CHECK_THROW(hasher.FinalizeNoPadding(digest.begin()), std::length_error);
+	}
+}
+
+BOOST_AUTO_TEST_SUITE_END()