SHA-256 Merkle tree: Difference between revisions
Added C++ solution
(Added C solution) |
(Added C++ solution) |
||
Line 78:
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}</lang>
{{out}}
<pre>
a4f902cf9d51fe51eda156a6792e1445dff65edf3a217a1f3334cc9cf1495c2c
</pre>
=={{header|C++}}==
{{libheader|OpenSSL}}
<lang cpp>#include <cstdlib>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <vector>
#include <openssl/sha.h>
class sha256 {
public:
sha256() { reset(); }
sha256(const sha256&) = delete;
sha256& operator=(const sha256&) = delete;
bool reset() {
return SHA256_Init(&context_) != 0;
}
bool update(const void* data, size_t length) {
return SHA256_Update(&context_, data, length) != 0;
}
bool finalize() {
return SHA256_Final(digest_, &context_) != 0;
}
const unsigned char* digest() const {
return digest_;
}
size_t length() const {
return SHA256_DIGEST_LENGTH;
}
private:
unsigned char digest_[SHA256_DIGEST_LENGTH];
SHA256_CTX context_;
};
void print_digest(std::ostream& out, const std::vector<unsigned char>& digest) {
out << std::hex;
for (size_t i = 0; i < digest.size(); ++i)
out << std::setw(2) << std::setfill('0') << static_cast<int>(digest[i]);
out << '\n';
}
std::vector<unsigned char> sha256_merkle_tree(std::istream& in, size_t block_size) {
std::vector<std::vector<unsigned char>> hashes;
std::vector<char> buffer(block_size);
sha256 md;
while (in) {
in.read(buffer.data(), block_size);
size_t bytes = in.gcount();
if (bytes == 0)
break;
md.reset();
md.update(buffer.data(), bytes);
md.finalize();
hashes.emplace_back(md.digest(), md.digest() + md.length());
}
if (hashes.empty())
return {};
size_t length = hashes.size();
while (length > 1) {
size_t j = 0;
for (size_t i = 0; i < length; i += 2, ++j) {
auto& digest1 = hashes[i];
auto& digest_out = hashes[j];
if (i + 1 < length) {
auto& digest2 = hashes[i + 1];
md.reset();
md.update(digest1.data(), digest1.size());
md.update(digest2.data(), digest2.size());
md.finalize();
digest_out.assign(md.digest(), md.digest() + md.length());
} else {
digest_out = digest1;
}
}
length = j;
}
return hashes[0];
}
int main(int argc, char** argv) {
if (argc != 2) {
std::cerr << "usage: " << argv[0] << " filename\n";
return EXIT_FAILURE;
}
std::ifstream in(argv[1]);
if (!in) {
std::cerr << "Cannot open file " << argv[1] << ".\n";
return EXIT_FAILURE;
}
print_digest(std::cout, sha256_merkle_tree(in, 1024));
return EXIT_SUCCESS;
}</lang>
| |||