1 files changed, 142 insertions, 0 deletions
diff --git a/libbutl/sha256.cxx b/libbutl/sha256.cxx
new file mode 100644
index 0000000..09f6844
--- /dev/null
+++ b/libbutl/sha256.cxx
@@ -0,0 +1,142 @@
+// file      : libbutl/sha256.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#include <libbutl/sha256.hxx>
+
+// C interface for sha256c.
+//
+#include <stdint.h>
+#include <stddef.h> // size_t
+
+#include <cctype>    // isxdigit()
+#include <stdexcept> // invalid_argument
+
+#include <libbutl/utility.hxx> // ucase(), lcase()
+
+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 += ucase (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 += lcase (c);
+      }
+    }
+
+    return s;
+  }
+}