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// file : butl/sha256 -*- C++ -*-
// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
// license : MIT; see accompanying LICENSE file
#ifndef BUTL_SHA256
#define BUTL_SHA256
#include <string>
#include <cstring> // strlen()
#include <cstdint>
#include <cstddef> // size_t
#include <butl/export>
namespace butl
{
// SHA256 checksum calculator.
//
// For a single chunk of data a sum can be obtained in one line, for
// example:
//
// cerr << sha256 ("123").string () << endl;
//
class LIBBUTL_EXPORT sha256
{
public:
sha256 ();
// Append binary data.
//
void
append (const void*, std::size_t);
sha256 (const void* b, std::size_t n): sha256 () {append (b, n);}
// Append string.
//
// Note that the hash includes the '\0' terminator. Failed that, a call
// with an empty string will be indistinguishable from no call at all.
//
void
append (const std::string& s) {append (s.c_str (), s.size () + 1);}
void
append (const char* s) {append (s, std::strlen (s) + 1);}
explicit
sha256 (const std::string& s): sha256 () {append (s);}
explicit
sha256 (const char* s): sha256 () {append (s);}
// Extract result.
//
// It can be obtained as either a 32-byte binary digest or as a 64-
// character hex-encoded C-string.
//
using digest_type = std::uint8_t[32];
const digest_type&
binary () const;
const char*
string () const;
public:
struct context
{
std::uint32_t state[8];
std::uint64_t count;
std::uint8_t buf[64];
};
private:
union
{
mutable context ctx_;
mutable char str_[65];
};
mutable digest_type bin_;
mutable bool done_;
};
// Convert a SHA256 string representation (64 hex digits) to the fingerprint
// canonical representation (32 colon-separated upper case hex digit pairs,
// like 01:AB:CD:...). Throw invalid_argument if the argument is not a valid
// SHA256 string.
//
LIBBUTL_EXPORT std::string
sha256_to_fingerprint (const std::string&);
// Convert a fingerprint (32 colon-separated hex digit pairs) to the SHA256
// string representation (64 lower case hex digits). Throw invalid_argument
// if the argument is not a valid fingerprint.
//
LIBBUTL_EXPORT std::string
fingerprint_to_sha256 (const std::string&);
};
#endif // BUTL_SHA256
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