- Add lib/crypto.

crypto/sha1.dart

Index: crypto/sha1.dart
===================================================================
--- crypto/sha1.dart	(revision 0)
+++ crypto/sha1.dart	(revision 0)
@@ -0,0 +1,72 @@
+class SHA1 {

[Mads Ager (google), 2012/04/24 09:57:46]

Copyright.

[Søren Gjesse, 2012/04/24 10:30:56]

Shouldn't we define an interface common for all hash algorithms?

[Ivan Posva, 2012/04/24 13:02:36]

Since this has only a static method an implementing an interface is unnecessary.
Mads has volunteered to define the logical extension of this to implement a
shared interface between different hashing algorithms which can be used with
chunked data and or streaming.

[Ivan Posva, 2012/04/24 13:02:36]

Done.

+  static List<int> digest(List<int> input,
+                          [int offset = 0,
+                           int len = null]) {
+    var input_len = input.length;
+    if ((offset < 0) || (offset > input_len)) {
+      throw new IllegalArgumentException("Invalid offset ($offset).");
+    }
+    if (len == null) {
+      len = input_len - offset;

[Ivan Posva, 2012/04/24 09:23:53]

It might be bad form to overwrite the input, what do you think?

[Søren Gjesse, 2012/04/24 10:30:56]

I have no problem with that.

+    }
+    if ((len < 0) || ((offset + len) > input_len)) {
+      throw new IllegalArgumentException("Invalid length ($len) for "
+          "offset ($offset) and input length (input_len).");
+    }
+
+    // Round up to 512 bit size.
+    var m_len = _roundUp((len * _BITS_PER_BYTE) + 65, _BITS_PER_CHUNK);
+    m_len = m_len ~/ _BITS_PER_WORD;
+    var m = new List<int>(m_len);
+        
+    _bytesToWords(input, offset, len, m, 0, m_len);
+ 
+    var l = len * 8;
+    var w = new List<int>(80);
+    var H0 = 0x67452301;
+    var H1 = 0xEFCDAB89;
+    var H2 = 0x98BADCFE;
+    var H3 = 0x10325476;
+    var H4 = 0xC3D2E1F0;
+ 
+    m[l >> 5] |= 0x80 << (24 - l % 32);
+    m[(((l + 64) >> 9) << 4) + 15] = l;

[Søren Gjesse, 2012/04/24 10:30:56]

If length is larger than (2^32 - 1) it should be split into two words.

[Ivan Posva, 2012/04/24 13:02:36]

Added a TODO to deal with this once we support arrays large enough to run into
this issue.

+
+    for (var i = 0; i < m_len; i += 16) {
+      var a = H0;
+      var b = H1;
+      var c = H2;
+      var d = H3;
+      var e = H4;
+      
+      for (var j = 0; j < 80; j++) {
+        if (j < 16) {
+          w[j] = m[i + j];
+        } else {
+          var n = w[j - 3] ^ w[j - 8] ^ w[j - 14] ^ w[j - 16];
+          w[j] = _rotl32(n, 1);
+        }
+
+        var t = _rotl32(a, 5) + e + w[j] +
+          ((j < 20) ? (((b & c) | (~b & d)) + 0x5A827999) :

[Mads Ager (google), 2012/04/24 09:57:46]

I would prefer the more readable version with if statements.

[Ivan Posva, 2012/04/24 13:02:36]

Done.

+           (j < 40) ? ((b ^ c ^ d) + 0x6ED9EBA1) :
+           (j < 60) ? (((b & c) | (b & d) | (c & d)) + 0x8F1BBCDC) :
+                      ((b ^ c ^ d) + 0xCA62C1D6));
+        e = d;
+        d = c;
+        c = _rotl32(b, 30);
+        b = a;
+        a = t & _MASK_32;
+      }
+      H0 = _add32(H0, a);
+      H1 = _add32(H1, b);
+      H2 = _add32(H2, c);
+      H3 = _add32(H3, d);
+      H4 = _add32(H4, e);
+    }
+    return _wordsToBytes([H0, H1, H2, H3, H4]);
+  }
+  
+  static final int _BITS_PER_CHUNK = 512;
+}
+