update checksum create/validate code based on Pieter Wuille's recent …

…research

README.md

@@ -48,3 +48,63 @@ sudo make install
 
 Now you can again try to build libbech32.
 
+### C++ Usage Example
+
+```cpp
+#include "libbech32.h"
+#include <iostream>
+#include <cassert>
+
+int main() {
+    // simple human readable part with some data
+    std::string hrp = "hello";
+    std::vector<unsigned char> data = {14, 15, 3, 31, 13};
+
+    // encode
+    std::string bstr = bech32::encode(hrp, data);
+
+    // prints "hello1w0rldcs7fw6" : "hello" + Bech32.separator + encoded data + 6 char checksum
+    std::cout << bstr << std::endl;
+
+    // decode
+    bech32::HrpAndDp hd = bech32::decode(bstr);
+
+    assert(hrp == hd.hrp);
+    assert(data == hd.dp);
+}
+```
+
+### C Usage Example
+
+```C
+#include "libbech32.h"
+#include <string.h>
+#include <stdio.h>
+#include <assert.h>
+
+int main() {
+    // simple human readable part with some data
+    char hrp[] = "hello";
+    unsigned char dp[] = {14, 15, 3, 31, 13};
+
+    // create output array for bech32 string
+    char bstr[sizeof(hrp) + 1 + sizeof(dp) + 6] = {0};
+
+    // encode
+    assert(bech32_encode(bstr, sizeof(bstr), hrp, sizeof(hrp), dp, sizeof(dp)) == E_BECH32_SUCCESS);
+
+    // prints "hello1w0rldcs7fw6" : "hello" + Bech32.separator + encoded data + 6 char checksum
+    printf("bech32 encoding of human-readable part \'hello\' and data part \'[14, 15, 3, 31, 13]\' is:\n");
+    printf("%s\n", bstr);
+
+    // allocate memory for decoded data
+    bech32_HrpAndDp * hrpdp = create_HrpAndDp_storage(bstr);
+
+    // decode
+    assert(bech32_decode(hrpdp, bstr, sizeof(bstr)) == E_BECH32_SUCCESS);
+    assert(strcmp(hrpdp->hrp, "hello") == 0);
+
+    // free memory
+    free_HrpAndDp_storage(hrpdp);
+}
+```

examples/CMakeLists.txt

@@ -7,10 +7,30 @@ set_target_properties(bech32_cpp_example PROPERTIES CXX_EXTENSIONS OFF)
 
 target_link_libraries(bech32_cpp_example bech32)
 
+##
+
+add_executable(bech32_cpp_usage_example cpp_usage_example.cpp)
+
+target_compile_features(bech32_cpp_usage_example PRIVATE cxx_std_11)
+target_compile_options(bech32_cpp_usage_example PRIVATE ${DCD_CXX_FLAGS})
+set_target_properties(bech32_cpp_usage_example PROPERTIES CXX_EXTENSIONS OFF)
+
+target_link_libraries(bech32_cpp_usage_example bech32)
+
+##
 
 add_executable(bech32_c_example c_example.c)
 
 target_compile_features(bech32_c_example PRIVATE c_std_99)
 set_target_properties(bech32_c_example PROPERTIES C_EXTENSIONS OFF)
 
 target_link_libraries(bech32_c_example bech32)
+
+##
+
+add_executable(bech32_c_usage_example c_usage_example.c)
+
+target_compile_features(bech32_c_usage_example PRIVATE c_std_99)
+set_target_properties(bech32_c_usage_example PROPERTIES C_EXTENSIONS OFF)
+
+target_link_libraries(bech32_c_usage_example bech32)

examples/c_example.c

@@ -6,7 +6,7 @@
 #undef NDEBUG
 #include <assert.h>
 
-int main() {
+void encodeAndDecode() {
 
     // hrp and data to encode
     char hrp[] = "example";
@@ -16,7 +16,7 @@ int main() {
     char bstr[sizeof(hrp) + 1 + sizeof(dp) + 6] = {0};
 
     // expected bech32 string output
-    char expected[] = "example1qpzry9x8gvmqvdw";
+    char expected[] = "example1qpzry9x8gnylnjs";
 
     // encode
     assert(bech32_encode(bstr, sizeof(bstr), hrp, sizeof(hrp), dp, sizeof(dp)) == E_BECH32_SUCCESS);
@@ -38,3 +38,66 @@ int main() {
     free_HrpAndDp_storage(hrpdp);
 
 }
+
+void decodeAndEncode() {
+
+    // bech32 string with extra invalid characters
+    char bstr[] = " example1:qpz!r--y9#x8&%&%gn-y-lnjs ";
+    // expected bech32 string output
+    char expected[] = "example1qpzry9x8gnylnjs";
+
+    // strip unwanted chars from bstr
+    bech32_stripUnknownChars(bstr, sizeof(bstr), bstr, sizeof(bstr));
+
+    // allocate memory for decoded data
+    bech32_HrpAndDp * hrpdp = create_HrpAndDp_storage(bstr);
+
+    // decode
+    assert(bech32_decode(hrpdp, bstr, sizeof(bstr)) == E_BECH32_SUCCESS);
+    assert(strcmp(hrpdp->hrp, "example") == 0);
+    assert(hrpdp->dp[0] == 0);
+    assert(hrpdp->dp[8] == 8);
+
+    // free memory
+    free_HrpAndDp_storage(hrpdp);
+
+}
+
+void badEncoding() {
+
+    // hrp and data to encode
+    char hrp[] = "example";
+    unsigned char dp[] = {0, 1, 2, 3, 4, 5, 6, 7, 33};
+
+    // create output array for bech32 string
+    char bstr[sizeof(hrp) + 1 + sizeof(dp) + 6] = {0};
+
+    // encode
+    assert(bech32_encode(bstr, sizeof(bstr), hrp, sizeof(hrp), dp, sizeof(dp)) == E_BECH32_UNKNOWN_ERROR);
+
+}
+
+void badDecoding() {
+
+    // bech32 string with extra invalid characters
+    char bstr[] = "example1qpzry9x8gnylnjs";
+    // simulate corrupted data--checksum verification will fail
+    bstr[10] = 'x';
+
+    // allocate memory for decoded data
+    bech32_HrpAndDp * hrpdp = create_HrpAndDp_storage(bstr);
+
+    // decode
+    assert(bech32_decode(hrpdp, bstr, sizeof(bstr)) == E_BECH32_INVALID_CHECKSUM);
+
+    // free memory
+    free_HrpAndDp_storage(hrpdp);
+
+}
+
+int main() {
+    encodeAndDecode();
+    decodeAndEncode();
+    badEncoding();
+    badDecoding();
+}

examples/c_usage_example.c

@@ -0,0 +1,33 @@
+#include "libbech32.h"
+#include <string.h>
+#include <stdio.h>
+
+// make sure we can check these examples even when building a release version
+#undef NDEBUG
+#include <assert.h>
+
+int main() {
+    // simple human readable part with some data
+    char hrp[] = "hello";
+    unsigned char dp[] = {14, 15, 3, 31, 13};
+
+    // create output array for bech32 string
+    char bstr[sizeof(hrp) + 1 + sizeof(dp) + 6] = {0};
+
+    // encode
+    assert(bech32_encode(bstr, sizeof(bstr), hrp, sizeof(hrp), dp, sizeof(dp)) == E_BECH32_SUCCESS);
+
+    // prints "hello1w0rldcs7fw6" : "hello" + Bech32.separator + encoded data + 6 char checksum
+    printf("bech32 encoding of human-readable part \'hello\' and data part \'[14, 15, 3, 31, 13]\' is:\n");
+    printf("%s\n", bstr);
+
+    // allocate memory for decoded data
+    bech32_HrpAndDp * hrpdp = create_HrpAndDp_storage(bstr);
+
+    // decode
+    assert(bech32_decode(hrpdp, bstr, sizeof(bstr)) == E_BECH32_SUCCESS);
+    assert(strcmp(hrpdp->hrp, "hello") == 0);
+
+    // free memory
+    free_HrpAndDp_storage(hrpdp);
+}

examples/cpp_example.cpp

@@ -15,36 +15,79 @@ void encodeAndDecode() {
     // encode
     std::string bstr = bech32::encode(hrp, data);
 
-    // will print "example1qpzry9x8gvmqvdw" ... last 6 characters are the checksum
+    // will print "example1qpzry9x8gnylnjs" ... last 6 characters are the checksum
     std::cout << R"(bech32 encoding of human-readable part 'example' and data part '[0, 1, 2, 3, 4, 5, 6, 7, 8]' is:)" << std::endl;
     std::cout << bstr << std::endl;
 
     // decode
-    bech32::HrpAndDp b = bech32::decode(bstr);
+    bech32::HrpAndDp hd = bech32::decode(bstr);
 
-    assert(hrp == b.hrp);
-    assert(data == b.dp);
+    assert(hrp == hd.hrp);
+    assert(data == hd.dp);
 }
 
 void decodeAndEncode() {
 
     // bech32 string with extra invalid characters
-    std::string bstr = "tx1:yjk!0-uq#ay-z%u4x-nk6u&-pc";
-    std::string expected = "tx1yjk0uqayzu4xnk6upc";
+    std::string bstr = " example1:qpz!r--y9#x8&%&%gn-y-lnjs ";
+    std::string expected = "example1qpzry9x8gnylnjs";
     // decode - make sure to strip invalid characters before trying to decode
-    bech32::HrpAndDp b = bech32::decode(bech32::stripUnknownChars(bstr));
+    bech32::HrpAndDp hd = bech32::decode(bech32::stripUnknownChars(bstr));
+
+    // verify decoding
+    assert(!hd.hrp.empty() && !hd.dp.empty());
 
     // encode
-    bstr = bech32::encode(b.hrp, b.dp);
+    bstr = bech32::encode(hd.hrp, hd.dp);
 
     // encoding of "cleaned" decoded data should match expected string
     assert(bstr == expected);
+
+    // simulate corrupted data--checksum verification will fail
+    bstr[10] = 'x';
+
+    // decode - make sure to strip invalid characters before trying to decode
+    hd = bech32::decode(bech32::stripUnknownChars(bstr));
+
+    // verify decoding failed
+    assert(hd.hrp.empty() && hd.dp.empty());
+
 }
 
-int main() {
+void badEncoding() {
 
-    encodeAndDecode();
+    // human-readable part
+    std::string hrp = "example";
+    // data values can be 0-31
+    std::vector<unsigned char> data = {0, 1, 2, 3, 4, 5, 6, 7, 33};
 
-    decodeAndEncode();
+    // encode
+    try {
+        std::string bstr = bech32::encode(hrp, data);
+    }
+    catch (std::exception &e) {
+        assert(strcmp(e.what(), "data value is out of range") == 0);
+    }
+}
+
+void badDecoding() {
+
+    // valid bech32 string
+    std::string bstr = "example1qpzry9x8gnylnjs";
+    // simulate corrupted data--checksum verification will fail
+    bstr[10] = 'x';
+
+    // decode
+    bech32::HrpAndDp hd = bech32::decode(bstr);
 
+    // verify decoding failed
+    assert(hd.hrp.empty() && hd.dp.empty());
+
+}
+
+int main() {
+    encodeAndDecode();
+    decodeAndEncode();
+    badEncoding();
+    badDecoding();
 }

examples/cpp_usage_example.cpp

@@ -0,0 +1,25 @@
+#include "libbech32.h"
+#include <iostream>
+
+// make sure we can check these examples even when building a release version
+#undef NDEBUG
+#include <cassert>
+
+int main() {
+    // simple human readable part with some data
+    std::string hrp = "hello";
+    std::vector<unsigned char> data = {14, 15, 3, 31, 13};
+
+    // encode
+    std::string bstr = bech32::encode(hrp, data);
+
+    // prints "hello1w0rldcs7fw6" : "hello" + Bech32.separator + encoded data + 6 char checksum
+    std::cout << R"(bech32 encoding of human-readable part 'hello' and data part '[14, 15, 3, 31, 13]' is:)" << std::endl;
+    std::cout << bstr << std::endl;
+
+    // decode
+    bech32::HrpAndDp hd = bech32::decode(bstr);
+
+    assert(hrp == hd.hrp);
+    assert(data == hd.dp);
+}

include/libbech32/libbech32.h

@@ -89,6 +89,7 @@ typedef enum bech32_error_e
     E_BECH32_UNKNOWN_ERROR,
     E_BECH32_NULL_ARGUMENT,
     E_BECH32_LENGTH_TOO_SHORT,
+    E_BECH32_INVALID_CHECKSUM,
     E_BECH32_MAX_ERROR
 } bech32_error;