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// file : butl/sha256.cxx -*- C++ -*-
// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
// license : MIT; see accompanying LICENSE file
#include <butl/sha256>
// C interface for sha256c.
//
#include <stdint.h>
#include <stddef.h> // size_t
#include <cctype> // isxdigit(), toupper(), tolower()
#include <stdexcept> // invalid_argument
using SHA256_CTX = butl::sha256::context;
extern "C"
{
static void SHA256_Init (SHA256_CTX*);
static void SHA256_Update (SHA256_CTX*, const void*, size_t);
static void SHA256_Final (uint8_t[32], SHA256_CTX*);
#include "sha256c.c"
}
using namespace std;
namespace butl
{
// sha256
//
sha256::
sha256 ()
: done_ (false)
{
SHA256_Init (&ctx_);
}
void sha256::
append (const void* b, size_t n)
{
SHA256_Update (&ctx_, b, n);
}
const sha256::digest_type& sha256::
binary () const
{
if (!done_)
{
SHA256_Final (bin_, &ctx_);
done_ = true;
str_[0] = '\0'; // Indicate we haven't computed the string yet.
}
return bin_;
}
static const char hex_map[16] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'a', 'b', 'c', 'd', 'e', 'f'};
const char* sha256::
string () const
{
if (!done_)
binary ();
if (str_[0] == '\0')
{
for (size_t i (0); i != 32; ++i)
{
str_[i * 2] = hex_map[bin_[i] >> 4];
str_[i * 2 + 1] = hex_map[bin_[i] & 0x0f];
}
str_[64] = '\0';
}
return str_;
}
// Conversion functions
//
string
sha256_to_fingerprint (const string& s)
{
auto bad = []() {throw invalid_argument ("invalid SHA256 string");};
size_t n (s.size ());
if (n != 64)
bad ();
string f;
f.reserve (n + 31);
for (size_t i (0); i < n; ++i)
{
char c (s[i]);
if (!isxdigit (c))
bad ();
if (i > 0 && i % 2 == 0)
f += ":";
f += toupper (c);
}
return f;
}
string
fingerprint_to_sha256 (const string& f)
{
auto bad = []() {throw invalid_argument ("invalid fingerprint");};
size_t n (f.size ());
if (n != 32 * 3 - 1)
bad ();
string s;
s.reserve (64);
for (size_t i (0); i < n; ++i)
{
char c (f[i]);
if ((i + 1) % 3 == 0)
{
if (c != ':')
bad ();
}
else
{
if (!isxdigit (c))
bad ();
s += tolower (c);
}
}
return s;
}
}
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