diff --git a/src/Makefile.am b/src/Makefile.am --- a/src/Makefile.am +++ b/src/Makefile.am @@ -92,6 +92,7 @@ base58.h \ bloom.h \ blockencodings.h \ + cashaddr.h \ chain.h \ chainparams.h \ chainparamsbase.h \ @@ -320,6 +321,7 @@ libbitcoin_common_a_SOURCES = \ amount.cpp \ base58.cpp \ + cashaddr.cpp \ chainparams.cpp \ coins.cpp \ compressor.cpp \ diff --git a/src/Makefile.test.include b/src/Makefile.test.include --- a/src/Makefile.test.include +++ b/src/Makefile.test.include @@ -80,6 +80,7 @@ test/blockencodings_tests.cpp \ test/bloom_tests.cpp \ test/bswap_tests.cpp \ + test/cashaddr_tests.cpp \ test/coins_tests.cpp \ test/compress_tests.cpp \ test/config_tests.cpp \ diff --git a/src/cashaddr.h b/src/cashaddr.h new file mode 100644 --- /dev/null +++ b/src/cashaddr.h @@ -0,0 +1,25 @@ +// Copyright (c) 2017 Pieter Wuille +// Copyright (c) 2017 The Bitcoin developers +// Distributed under the MIT software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +// Cashaddr is an address format inspired by bech32. + +#include +#include +#include + +namespace cashaddr { + +/** + * Encode a cashaddr string. Returns the empty string in case of failure. + */ +std::string Encode(const std::string &prefix, + const std::vector &values); + +/** + * Decode a cashaddr string. Returns (prefix, data). Empty prefix means failure. + */ +std::pair> Decode(const std::string &str); + +} // namespace cashaddr diff --git a/src/cashaddr.cpp b/src/cashaddr.cpp new file mode 100644 --- /dev/null +++ b/src/cashaddr.cpp @@ -0,0 +1,295 @@ +// Copyright (c) 2017 Pieter Wuille +// Copyright (c) 2017 The Bitcoin developers +// Distributed under the MIT software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +#include "cashaddr.h" + +namespace { + +typedef std::vector data; + +/** + * The cashaddr character set for encoding. + */ +const char *CHARSET = "qpzry9x8gf2tvdw0s3jn54khce6mua7l"; + +/** + * The cashaddr character set for decoding. + */ +const int8_t CHARSET_REV[128] = { + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 15, -1, 10, 17, 21, 20, 26, 30, 7, + 5, -1, -1, -1, -1, -1, -1, -1, 29, -1, 24, 13, 25, 9, 8, 23, -1, 18, 22, + 31, 27, 19, -1, 1, 0, 3, 16, 11, 28, 12, 14, 6, 4, 2, -1, -1, -1, -1, + -1, -1, 29, -1, 24, 13, 25, 9, 8, 23, -1, 18, 22, 31, 27, 19, -1, 1, 0, + 3, 16, 11, 28, 12, 14, 6, 4, 2, -1, -1, -1, -1, -1}; + +/** + * Concatenate two byte arrays. + */ +data Cat(data x, const data &y) { + x.insert(x.end(), y.begin(), y.end()); + return x; +} + +/** + * This function will compute what 8 5-bit values to XOR into the last 8 input + * values, in order to make the checksum 0. These 8 values are packed together + * in a single 40-bit integer. The higher bits correspond to earlier values. + */ +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) = 1*x^5 + v0*x^4 + v1*x^3 + v2*x^2 + v3*x + v4. + * The implicit 1 guarantees that [v0,v1,v2,...] has a distinct checksum + * from [0,v0,v1,v2,...]. + * + * The output is a 40-bit integer whose 5-bit groups are the coefficients of + * the remainder of v(x) mod g(x), where g(x) is the cashaddr generator, x^8 + * + {19}*x^7 + {3}*x^6 + {25}*x^5 + {11}*x^4 + {25}*x^3 + {3}*x^2 + {19}*x + * + {1}. g(x) is chosen in such a way that the resulting code is a BCH + * code, guaranteeing detection of up to 4 errors within a window of 1025 + * characters. Among the various possible BCH codes, one was selected to in + * fact guarantee detection of up to 5 errors within a window of 160 + * characters and 6 erros within a window of 126 characters. In addition, + * the code guarantee the detection of a burst of up to 8 errors. + * + * Note that the coefficients are elements of GF(32), here represented as + * decimal numbers between {}. In this finite field, addition is just XOR of + * the corresponding numbers. For example, {27} + {13} = {27 ^ 13} = {22}. + * Multiplication is more complicated, and requires treating the bits of + * values themselves as coefficients of a polynomial over a smaller field, + * GF(2), and multiplying those polynomials mod a^5 + a^3 + 1. For example, + * {5} * {26} = (a^2 + 1) * (a^4 + a^3 + a) = (a^4 + a^3 + a) * a^2 + (a^4 + + * a^3 + a) = a^6 + a^5 + a^4 + a = a^3 + 1 (mod a^5 + a^3 + 1) = {9}. + * + * During the course of the loop below, `c` contains the bitpacked + * coefficients of the polynomial constructed from just the values of v that + * were processed so far, mod g(x). In the above example, `c` initially + * corresponds to 1 mod (x), and after processing 2 inputs of v, it + * corresponds to x^2 + v0*x + v1 mod g(x). As 1 mod g(x) = 1, that is the + * starting value for `c`. + */ + uint64_t c = 1; + for (uint8_t d : v) { + /** + * We want to update `c` to correspond to a polynomial with one extra + * term. If the initial value of `c` consists of the coefficients of + * c(x) = f(x) mod g(x), we modify it to correspond to + * c'(x) = (f(x) * x + d) mod g(x), where d is the next input to + * process. + * + * Simplifying: + * c'(x) = (f(x) * x + d) mod g(x) + * ((f(x) mod g(x)) * x + d) mod g(x) + * (c(x) * x + d) mod g(x) + * If c(x) = c0*x^5 + c1*x^4 + c2*x^3 + c3*x^2 + c4*x + c5, we want to + * compute + * c'(x) = (c0*x^5 + c1*x^4 + c2*x^3 + c3*x^2 + c4*x + c5) * x + d + * mod g(x) + * = c0*x^6 + c1*x^5 + c2*x^4 + c3*x^3 + c4*x^2 + c5*x + d + * mod g(x) + * = c0*(x^6 mod g(x)) + c1*x^5 + c2*x^4 + c3*x^3 + c4*x^2 + + * c5*x + d + * If we call (x^6 mod g(x)) = k(x), this can be written as + * c'(x) = (c1*x^5 + c2*x^4 + c3*x^3 + c4*x^2 + c5*x + d) + c0*k(x) + */ + + // First, determine the value of c0: + uint8_t c0 = c >> 35; + + // Then compute c1*x^5 + c2*x^4 + c3*x^3 + c4*x^2 + c5*x + d: + c = ((c & 0x07ffffffff) << 5) ^ d; + + // Finally, for each set bit n in c0, conditionally add {2^n}k(x): + if (c0 & 0x01) { + // k(x) = {19}*x^7 + {3}*x^6 + {25}*x^5 + {11}*x^4 + {25}*x^3 + + // {3}*x^2 + {19}*x + {1} + c ^= 0x98f2bc8e61; + } + + if (c0 & 0x02) { + // {2}k(x) = {15}*x^7 + {6}*x^6 + {27}*x^5 + {22}*x^4 + {27}*x^3 + + // {6}*x^2 + {15}*x + {2} + c ^= 0x79b76d99e2; + } + + if (c0 & 0x04) { + // {4}k(x) = {30}*x^7 + {12}*x^6 + {31}*x^5 + {5}*x^4 + {31}*x^3 + + // {12}*x^2 + {30}*x + {4} + c ^= 0xf33e5fb3c4; + } + + if (c0 & 0x08) { + // {8}k(x) = {21}*x^7 + {24}*x^6 + {23}*x^5 + {10}*x^4 + {23}*x^3 + + // {24}*x^2 + {21}*x + {8} + c ^= 0xae2eabe2a8; + } + + if (c0 & 0x10) { + // {16}k(x) = {3}*x^7 + {25}*x^6 + {7}*x^5 + {20}*x^4 + {7}*x^3 + + // {25}*x^2 + {3}*x + {16} + c ^= 0x1e4f43e470; + } + } + + return c; +} + +/** + * Convert to lower case. + * + * Assume the input is a character. + */ +inline uint8_t LowerCase(uint8_t c) { + // ASCII black magic. + return c | 0x20; +} + +/** + * Expand the address prefix for the checksum computation. + */ +data ExpandPrefix(const std::string &prefix) { + data ret; + ret.resize(prefix.size() + 1); + for (size_t i = 0; i < prefix.size(); ++i) { + ret[i] = prefix[i] & 0x1f; + } + + ret[prefix.size()] = 0; + return ret; +} + +/** + * Verify a checksum. + */ +bool VerifyChecksum(const std::string &prefix, const data &values) { + /** + * PolyMod computes what value to xor into the final values to make the + * checksum 0. However, if we required that the checksum was 0, it would be + * the case that appending a 0 to a valid list of values would result in a + * new valid list. For that reason, cashaddr requires the resulting checksum + * to be 1 instead. + */ + return PolyMod(Cat(ExpandPrefix(prefix), values)) == 1; +} + +/** + * Create a checksum. + */ +data CreateChecksum(const std::string &prefix, const data &values) { + data enc = Cat(ExpandPrefix(prefix), values); + // Append 8 zeroes. + enc.resize(enc.size() + 8); + // Determine what to XOR into those 8 zeroes. + uint64_t mod = PolyMod(enc) ^ 1; + data ret(8); + for (size_t i = 0; i < 8; ++i) { + // Convert the 5-bit groups in mod to checksum values. + ret[i] = (mod >> (5 * (7 - i))) & 0x1f; + } + + return ret; +} + +} // namespace + +namespace cashaddr { + +/** + * Encode a cashaddr string. + */ +std::string Encode(const std::string &prefix, const data &values) { + data checksum = CreateChecksum(prefix, values); + data combined = Cat(values, checksum); + std::string ret = prefix + ':'; + + ret.reserve(ret.size() + combined.size()); + for (uint8_t c : combined) { + ret += CHARSET[c]; + } + + return ret; +} + +/** + * Decode a cashaddr string. + */ +std::pair Decode(const std::string &str) { + // Go over the string and do some sanity checks. + bool lower = false, upper = false; + size_t prefixSize = 0; + for (size_t i = 0; i < str.size(); ++i) { + uint8_t c = str[i]; + if (c >= 'a' && c <= 'z') { + lower = true; + continue; + } + + if (c >= 'A' && c <= 'Z') { + upper = true; + continue; + } + + if (c >= '0' && c <= '9') { + // We cannot have numbers in the prefix. + if (prefixSize == 0) { + return {}; + } + + continue; + } + + if (c == ':') { + // The separator must not be the first character, and there must not + // be 2 separators. + if (i == 0 || prefixSize != 0) { + return {}; + } + + prefixSize = i; + continue; + } + + // We have an unexpected character. + return {}; + } + + // We must have a prefix and a data part and we can't have both uppercase + // and lowercase. + if ((prefixSize == 0) || (upper && lower)) { + return {}; + } + + // Get the prefix. + std::string prefix; + prefix.reserve(prefixSize); + for (size_t i = 0; i < prefixSize; ++i) { + prefix += LowerCase(str[i]); + } + + // Decode values. + const size_t valuesSize = str.size() - 1 - prefixSize; + data values(valuesSize); + for (size_t i = 0; i < valuesSize; ++i) { + uint8_t c = str[i + prefixSize + 1]; + // We have an invalid char in there. + if (c > 127 || CHARSET_REV[c] == -1) { + return {}; + } + + values[i] = CHARSET_REV[c]; + } + + // Verify the checksum. + if (!VerifyChecksum(prefix, values)) { + return {}; + } + + return {prefix, data(values.begin(), values.end() - 8)}; +} + +} // namespace cashaddr diff --git a/src/test/cashaddr_tests.cpp b/src/test/cashaddr_tests.cpp new file mode 100644 --- /dev/null +++ b/src/test/cashaddr_tests.cpp @@ -0,0 +1,87 @@ +// Copyright (c) 2017 Pieter Wuille +// Copyright (c) 2017 The Bitcoin developers +// Distributed under the MIT software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +#include "cashaddr.h" +#include "test/test_bitcoin.h" + +#include + +BOOST_FIXTURE_TEST_SUITE(cashaddr_tests, BasicTestingSetup) + +bool CaseInsensitiveEqual(const std::string &s1, const std::string &s2) { + if (s1.size() != s2.size()) { + return false; + } + + for (size_t i = 0; i < s1.size(); ++i) { + char c1 = s1[i]; + if (c1 >= 'A' && c1 <= 'Z') { + c1 -= ('A' - 'a'); + } + char c2 = s2[i]; + if (c2 >= 'A' && c2 <= 'Z') { + c2 -= ('A' - 'a'); + } + if (c1 != c2) { + return false; + } + } + + return true; +} + +BOOST_AUTO_TEST_CASE(cashaddr_testvectors_valid) { + static const std::string CASES[] = { + "prefix:x64nx6hz", + "PREFIX:X64NX6HZ", + "p:gpf8m4h7", + "bitcoincash:qpzry9x8gf2tvdw0s3jn54khce6mua7lcw20ayyn", + "bcctest:testnetaddressqm3zpk4w", + "bccreg:555555555555555555555555555555555555555555555lmxjk3an", + }; + for (const std::string &str : CASES) { + auto ret = cashaddr::Decode(str); + BOOST_CHECK_MESSAGE(!ret.first.empty(), str); + std::string recode = cashaddr::Encode(ret.first, ret.second); + BOOST_CHECK_MESSAGE(!recode.empty(), str); + BOOST_CHECK_MESSAGE(CaseInsensitiveEqual(str, recode), str); + } +} + +BOOST_AUTO_TEST_CASE(cashaddr_testvectors_invalid) { + static const std::string CASES[] = { + "prefix:x32nx6hz", + "prEfix:x64nx6hz", + "prefix:x64nx6Hz", + "pref1x:6m8cxv73", + "prefix:", + ":u9wsx07j", + "bccreg:555555555555555555x55555555555555555555555555lmxjk3an", + "bccreg:555555555555555555555555555555551555555555555lmxjk3an", + "pre:fix:x32nx6hz", + "prefixx64nx6hz", + }; + for (const std::string &str : CASES) { + auto ret = cashaddr::Decode(str); + BOOST_CHECK_MESSAGE(ret.first.empty(), str); + } +} + +BOOST_AUTO_TEST_CASE(cashaddr_rawencode) { + typedef std::pair> raw; + + raw toEncode; + toEncode.first = "helloworld"; + toEncode.second = {0x1f, 0x0d}; + + std::string encoded = cashaddr::Encode(toEncode.first, toEncode.second); + raw decoded = cashaddr::Decode(encoded); + + BOOST_CHECK_EQUAL(toEncode.first, decoded.first); + BOOST_CHECK_EQUAL_COLLECTIONS(begin(toEncode.second), end(toEncode.second), + begin(decoded.second), end(decoded.second)); +} + +BOOST_AUTO_TEST_SUITE_END()