Buffer sizes

	workingBlock should be the InputBlockSize and currentBlock the
	OutputBlockSize. Allocate currentBlock lazily.

	Test contributed by Bassam Tabbara.
	Fixes bug #644740.

mcs/class/corlib/System.Security.Cryptography/CryptoStream.cs

@@ -71,14 +71,7 @@ namespace System.Security.Cryptography {
 			_mode = mode;
 			_disposed = false;
 			if (transform != null) {
-				if (mode == CryptoStreamMode.Read) {
-					_currentBlock = new byte [transform.InputBlockSize];
-					_workingBlock = new byte [transform.InputBlockSize];
-				}
-				else if (mode == CryptoStreamMode.Write) {
-					_currentBlock = new byte [transform.OutputBlockSize];
-					_workingBlock = new byte [transform.OutputBlockSize];
-				}
+				_workingBlock = new byte [transform.InputBlockSize];
 			}
 		}
 
@@ -250,7 +243,7 @@ namespace System.Security.Cryptography {
 			}
 
 			if (_stream == null)
-				throw new ArgumentNullException ("inner stream was diposed");
+				throw new ArgumentNullException ("inner stream was disposed");
 
 			int buffer_length = count;
 
@@ -267,6 +260,9 @@ namespace System.Security.Cryptography {
 			int bufferPos = offset;
 			while (count > 0) {
 				if (_partialCount == _transform.InputBlockSize) {
+					if (_currentBlock == null)
+						_currentBlock = new byte [_transform.OutputBlockSize];
+
 					// use partial block to avoid (re)allocation
 					int len = _transform.TransformBlock (_workingBlock, 0, _partialCount, _currentBlock, 0);
 					_stream.Write (_currentBlock, 0, len);

mcs/class/corlib/Test/System.Security.Cryptography/CryptoStreamTest.cs

@@ -1457,6 +1457,16 @@ namespace MonoTests.System.Security.Cryptography {
 			CryptoStream cs = new CryptoStream (Stream.Null, SHA1.Create (), (CryptoStreamMode) 0xff);
 		}
 
+		[Test]
+		public void OutputBlock_Smaller ()
+		{
+			// The OutputBlockSize is smaller than the InputBlockSize
+			using (CryptoStream cs = new CryptoStream(Stream.Null, new MyCryptAlgorithm(), CryptoStreamMode.Write)) {
+				byte[] buffer = new byte[512 * 1024];
+				cs.Write(buffer, 0, buffer.Length);
+			}
+		}
+
 		class MyCryptoStream : CryptoStream {
 			public bool DisposeCalled { get; private set;}
 
@@ -1629,6 +1639,25 @@ namespace MonoTests.System.Security.Cryptography {
 			}
 		}
 
+		class MyCryptAlgorithm : ICryptoTransform {
+			public bool CanReuseTransform { get { return true; } }
+			public bool CanTransformMultipleBlocks { get { return false; } }
+			public int InputBlockSize { get { return 128 * 1024; } }
+			public int OutputBlockSize { get { return 64 * 1024; } }
+
+			public int TransformBlock(byte[] inputBuffer, int inputOffset, int inputCount, byte[] outputBuffer, int outputOffset)
+			{
+				return this.OutputBlockSize;
+			}
+
+			public byte[] TransformFinalBlock(byte[] inputBuffer, int inputOffset, int inputCount)
+			{
+				return new byte[this.OutputBlockSize];
+			}
+
+			public void Dispose() {}
+		}
+
 		class MyStream : Stream {
 			public bool FlushCounterEnabled;
 			public int FlushCounter;