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[mono.git] / mcs / class / corlib / System.Security.Cryptography / Rfc2898DeriveBytes.cs

diff --git a/mcs/class/corlib/System.Security.Cryptography/Rfc2898DeriveBytes.cs b/mcs/class/corlib/System.Security.Cryptography/Rfc2898DeriveBytes.cs
index a6b5a816ee63992c6e9821a7d0447b28952b285c..98d7e1f8e780b5b11961f0d4824ddfd32c6a6295 100755 (executable)
--- a/mcs/class/corlib/System.Security.Cryptography/Rfc2898DeriveBytes.cs
+++ b/mcs/class/corlib/System.Security.Cryptography/Rfc2898DeriveBytes.cs
@@ -19,9 +19,13 @@ namespace System.Security.Cryptography {
        public class Rfc2898DeriveBytes : DeriveBytes {
 
                private const int defaultIterations = 1000;
+
                private int _iteration;
                private byte[] _salt;
                private HMACSHA1 _hmac;
+               private byte[] _buffer;
+               private int _pos;
+               private int _f;
 
                // constructors
 
@@ -103,27 +107,42 @@ namespace System.Security.Cryptography {
 
                public override byte[] GetBytes (int cb) 
                {
+                       if (cb < 1)
+                               throw new ArgumentOutOfRangeException ("cb");
+
                        int l = cb / 20;        // HMACSHA1 == 160 bits == 20 bytes
                        int r = cb % 20;        // remainder
                        if (r != 0)
                                l++;            // rounding up
 
                        byte[] result = new byte [cb];
-                       int pos = 0;
+                       int rpos = 0;
+                       if (_pos > 0) {
+                               int count = Math.Min (20 - _pos, cb);
+                               Buffer.BlockCopy (_buffer, _pos, result, 0, count);
+                               if (count >= cb)
+                                       return result;
+                               _pos = 0;
+                               rpos = 20 - cb;
+                               r = cb - rpos;
+                       }
 
-                       for (int i=0; i < l; i++) {
-                               byte[] t =  F (_salt, _iteration, l);
-                               int count = ((i == l - 1) ? r : 20);
-                               Buffer.BlockCopy (t, 0, result, pos, count);
-                               pos += count;
+                       for (int i=1; i <= l; i++) {
+                               _buffer = F (_salt, _iteration, ++_f);
+                               int count = ((i == l) ? r : 20);
+                               Buffer.BlockCopy (_buffer, _pos, result, rpos, count);
+                               rpos += _pos + count;
+                               _pos = ((count == 20) ? 0 : count);
                        }
 
                        return result;
                }
                
-               [MonoTODO]
                public override void Reset () 
                {
+                       _buffer = null;
+                       _pos = 0;
+                       _f = 0;
                }
        } 
 }