Merge #595: Add unit test for the PolyMod method in b(l)ech32

4a218cd Fix linter by exporting b(l)ech32 internals (Steven Roose)
99b047c Add additional blech32 unit test (Steven Roose)
6412970 Fix bug in blech32 (Steven Roose)
0de2b05 Add unit test for the PolyMod method in b(l)ech32 (Steven Roose)

Pull request description:

Tree-SHA512: 9d574376b6471742283d0d145359d8d674b7e95fd40f52396c6fc5f671dc262526624d1d15cb8ab7b4517a8b2501405dd0f680f69dfc41dabb0eb11d7bbbfe88

src/Makefile.test.include

@@ -39,6 +39,7 @@ BITCOIN_TESTS =\
   test/base58_tests.cpp \
   test/base64_tests.cpp \
   test/bech32_tests.cpp \
+  test/blech32_tests.cpp \
   test/bip32_tests.cpp \
   test/blockchain_tests.cpp \
   test/blockencodings_tests.cpp \

src/bech32.cpp

@@ -4,7 +4,7 @@
 
 #include <bech32.h>
 
-namespace
+namespace bech32
 {
 
 typedef std::vector<uint8_t> data;
@@ -138,11 +138,6 @@ data CreateChecksum(const std::string& hrp, const data& values)
     return ret;
 }
 
-} // namespace
-
-namespace bech32
-{
-
 /** Encode a Bech32 string. */
 std::string Encode(const std::string& hrp, const data& values) {
     data checksum = CreateChecksum(hrp, values);

src/bech32.h

@@ -25,6 +25,9 @@ std::string Encode(const std::string& hrp, const std::vector<uint8_t>& values);
 /** Decode a Bech32 string. Returns (hrp, data). Empty hrp means failure. */
 std::pair<std::string, std::vector<uint8_t>> Decode(const std::string& str);
 
+/// Exported for testing.
+uint32_t PolyMod(const std::vector<uint8_t>& v);
+
 } // namespace bech32
 
 #endif // BITCOIN_BECH32_H

src/blech32.cpp

@@ -11,7 +11,7 @@
  * TODO: Update comments
  */
 
-namespace
+namespace blech32
 {
 
 typedef std::vector<uint8_t> data;
@@ -41,7 +41,7 @@ data Cat(data x, const data& y)
 /** This function will compute what 6 5-bit values to XOR into the last 6 input values, in order to
  *  make the checksum 0. These 6 values are packed together in a single 30-bit integer. The higher
  *  bits correspond to earlier values. */
-uint32_t PolyMod(const data& v)
+uint64_t PolyMod(const data& v)
 {
     // The input is interpreted as a list of coefficients of a polynomial over F = GF(32), with an
     // implicit 1 in front. If the input is [v0,v1,v2,v3,v4], that polynomial is v(x) =
@@ -136,7 +136,7 @@ data CreateChecksum(const std::string& hrp, const data& values)
 {
     data enc = Cat(ExpandHRP(hrp), values);
     enc.resize(enc.size() + 12); // ELEMENTS: Append 6->12 zeroes
-    uint32_t mod = PolyMod(enc) ^ 1; // Determine what to XOR into those 6 zeroes.
+    uint64_t mod = PolyMod(enc) ^ 1; // Determine what to XOR into those 6 zeroes.
     data ret(12); // ELEMENTS: 6->12
     for (size_t i = 0; i < 12; ++i) { // ELEMENTS: 6->12
         // Convert the 5-bit groups in mod to checksum values.
@@ -145,11 +145,6 @@ data CreateChecksum(const std::string& hrp, const data& values)
     return ret;
 }
 
-} // namespace
-
-namespace blech32
-{
-
 /** Encode a Blech32 string. */
 std::string Encode(const std::string& hrp, const data& values) {
     data checksum = CreateChecksum(hrp, values);

src/blech32.h

@@ -25,6 +25,11 @@ std::string Encode(const std::string& hrp, const std::vector<uint8_t>& values);
 /** Decode a Bech32 string. Returns (hrp, data). Empty hrp means failure. */
 std::pair<std::string, std::vector<uint8_t>> Decode(const std::string& str);
 
+/// Exported for testing.
+uint64_t PolyMod(const std::vector<uint8_t>& v);
+/// Exported for testing.
+std::vector<uint8_t> CreateChecksum(const std::string& hrp, const std::vector<uint8_t>& values);
+
 } // namespace blech32
 
 #endif // BITCOIN_BLECH32_H

src/test/bech32_tests.cpp

@@ -66,4 +66,22 @@ BOOST_AUTO_TEST_CASE(bip173_testvectors_invalid)
     }
 }
 
+BOOST_AUTO_TEST_CASE(bech32_polymod_sanity)
+{
+    std::vector<unsigned char> data(40);
+    GetRandBytes(data.data(), data.size());
+
+    std::vector<unsigned char> base32;
+    ConvertBits<8, 5, true>([&](unsigned char c) { base32.push_back(c); }, data.begin(), data.end());
+    uint64_t plm1 = bech32::PolyMod(base32);
+
+    // Now add 1023 zeros.
+    for (auto i = 0; i < 1023; i++) {
+        base32.push_back(0);
+    }
+    uint64_t plm2 = bech32::PolyMod(base32);
+
+    BOOST_CHECK_EQUAL(plm1, plm2);
+}
+
 BOOST_AUTO_TEST_SUITE_END()

src/test/blech32_tests.cpp

@@ -0,0 +1,46 @@
+// Copyright (c) 2017 Pieter Wuille
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <blech32.h>
+#include <random.h>
+#include <utilstrencodings.h>
+#include <test/test_bitcoin.h>
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_FIXTURE_TEST_SUITE(blech32_tests, BasicTestingSetup)
+
+BOOST_AUTO_TEST_CASE(blech32_polymod_sanity)
+{
+    std::vector<unsigned char> data(40);
+    GetRandBytes(data.data(), data.size());
+
+    std::vector<unsigned char> base32;
+    ConvertBits<8, 5, true>([&](unsigned char c) { base32.push_back(c); }, data.begin(), data.end());
+    uint64_t plm1 = blech32::PolyMod(base32);
+
+    // Now add 1023 zeros.
+    for (auto i = 0; i < 1023; i++) {
+        base32.push_back(0);
+    }
+    uint64_t plm2 = blech32::PolyMod(base32);
+
+    BOOST_CHECK_EQUAL(plm1, plm2);
+}
+
+BOOST_AUTO_TEST_CASE(blech32_checksum)
+{
+    std::vector<unsigned char> vector{7,2,3,4,5,6,7,8,9,234,123,213,16};
+    std::vector<unsigned char> b32;
+    ConvertBits<8, 5, true>([&](unsigned char c) { b32.push_back(c); }, vector.begin(), vector.end());
+    std::vector<unsigned char> cs = blech32::CreateChecksum("lq", b32);
+
+    std::vector<unsigned char> expected_cs{22,13,13,5,4,4,23,7,28,21,30,12};
+    for (size_t i = 0; i < expected_cs.size(); i++) {
+        BOOST_CHECK_EQUAL(expected_cs[i], cs[i]);
+    }
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+