From d928de165f8bb896ee77f5668f35611f57429c93 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Sun, 28 Feb 2016 13:15:23 +0200
Subject: Add SHA256 calculator

Based on the sha256c.c file from the FreeBSD project and ported to compile on
Linux, Mac OS, and Windows. The file is licensed under the simplified/2-clause
BSD license so the library is now MIT/BSD-licensed.
---
 butl/sha256 | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 butl/sha256

(limited to 'butl/sha256')

diff --git a/butl/sha256 b/butl/sha256
new file mode 100644
index 0000000..3fc9e63
--- /dev/null
+++ b/butl/sha256
@@ -0,0 +1,76 @@
+// 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
+
+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 sha256
+  {
+  public:
+    sha256 ();
+    explicit sha256 (const std::string& s): sha256 () {append (s);}
+    explicit sha256 (const char* s): sha256 () {append (s);}
+    sha256 (const void* b, std::size_t n): sha256 () {append (b, n);}
+
+    // Append string (without the traling '\0').
+    //
+    void
+    append (const std::string& s) {append (s.c_str (), s.size ());}
+
+    // Append C-string (without the traling '\0').
+    //
+    void
+    append (const char* s) {append (s, std::strlen (s));}
+
+    // Append binary data.
+    //
+    void
+    append (const void*, std::size_t);
+
+    // 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_;
+  };
+};
+
+#endif // BUTL_SHA256
-- 
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