base64Transforms.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / Security / Cryptography / base64Transforms.cs / 1305376 / base64Transforms.cs
                        
                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
// [....]
// 
 
//
// Base64Transform.cs 
//

// This file contains two ICryptoTransforms: ToBase64Transform and FromBase64Transform
// they may be attached to a CryptoStream in either read or write mode 

namespace System.Security.Cryptography { 
    using System; 
    using System.IO;
    using System.Text; 
    using System.Diagnostics.Contracts;

#if !SILVERLIGHT
    [Serializable] 
[System.Runtime.InteropServices.ComVisible(true)]
#endif // !SILVERLIGHT 
    public enum FromBase64TransformMode { 
        IgnoreWhiteSpaces = 0,
        DoNotIgnoreWhiteSpaces = 1, 
    }

#if !SILVERLIGHT
[System.Runtime.InteropServices.ComVisible(true)] 
    public class ToBase64Transform : ICryptoTransform {
        // converting to Base64 takes 3 bytes input and generates 4 bytes output 
        public int InputBlockSize { 
            get { return(3); }
        } 

        public int OutputBlockSize {
            get { return(4); }
        } 

        public bool CanTransformMultipleBlocks { 
            get { return(false); } 
        }
 
        public virtual bool CanReuseTransform {
            get { return(true); }
        }
 
        public int TransformBlock(byte[] inputBuffer, int inputOffset, int inputCount, byte[] outputBuffer, int outputOffset) {
            // Do some validation 
            if (inputBuffer == null) throw new ArgumentNullException("inputBuffer"); 
            if (inputOffset < 0) throw new ArgumentOutOfRangeException("inputOffset", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
            if (inputCount < 0 || (inputCount > inputBuffer.Length)) throw new ArgumentException(Environment.GetResourceString("Argument_InvalidValue")); 
            if ((inputBuffer.Length - inputCount) < inputOffset) throw new ArgumentException(Environment.GetResourceString("Argument_InvalidOffLen"));
            Contract.EndContractBlock();

            // for now, only convert 3 bytes to 4 
            char[] temp = new char[4];
            Convert.ToBase64CharArray(inputBuffer, inputOffset, 3, temp, 0); 
            byte[] tempBytes = Encoding.ASCII.GetBytes(temp); 
            if (tempBytes.Length != 4) throw new CryptographicException(Environment.GetResourceString( "Cryptography_SSE_InvalidDataSize" ));
            Buffer.BlockCopy(tempBytes, 0, outputBuffer, outputOffset, tempBytes.Length); 
            return(tempBytes.Length);
        }

        public byte[] TransformFinalBlock(byte[] inputBuffer, int inputOffset, int inputCount) { 
            // Do some validation
            if (inputBuffer == null) throw new ArgumentNullException("inputBuffer"); 
            if (inputOffset < 0) throw new ArgumentOutOfRangeException("inputOffset", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum")); 
            if (inputCount < 0 || (inputCount > inputBuffer.Length)) throw new ArgumentException(Environment.GetResourceString("Argument_InvalidValue"));
            if ((inputBuffer.Length - inputCount) < inputOffset) throw new ArgumentException(Environment.GetResourceString("Argument_InvalidOffLen")); 
            Contract.EndContractBlock();

            // Convert.ToBase64CharArray already does padding, so all we have to check is that
            // the inputCount wasn't 0 

            // again, for now only a block at a time 
            if (inputCount == 0) { 
                return(new byte[0]);
            } else { 
                char[] temp = new char[4];
                Convert.ToBase64CharArray(inputBuffer, inputOffset, inputCount, temp, 0);
                byte[] tempBytes = Encoding.ASCII.GetBytes(temp);
                return(tempBytes); 
            }
        } 
 
        // must implement IDisposable, but in this case there's nothing to do.
 
        public void Dispose() {
            Clear();
        }
 
        public void Clear() {
            Dispose(true); 
            GC.SuppressFinalize(this); 
        }
 
        protected virtual void Dispose(bool disposing) {
        }

        ~ToBase64Transform() { 
            //
            // A finalizer is not necessary here, however since we shipped a finalizer that called 
            // Dispose(false) in v2.0, we need to keep it around in case any existing code had subclassed 
            // this transform and expects to have a base class finalizer call its dispose method
            // 

            Dispose(false);
        }
    } 
#endif // !SILVERLIGHT
 
#if !SILVERLIGHT 
[System.Runtime.InteropServices.ComVisible(true)]
#endif // !SILVERLIGHT 
    public class FromBase64Transform : ICryptoTransform {
        private byte[] _inputBuffer = new byte[4];
        private int    _inputIndex;
 
        private FromBase64TransformMode _whitespaces;
 
        // Constructors 
        public FromBase64Transform() : this(FromBase64TransformMode.IgnoreWhiteSpaces) {}
        public FromBase64Transform(FromBase64TransformMode whitespaces) { 
            _whitespaces = whitespaces;
            _inputIndex = 0;
        }
 
        // converting from Base64 generates 3 bytes output from each 4 bytes input block
        public int InputBlockSize { 
            get { return(1); } 
        }
 
        public int OutputBlockSize {
            get { return(3); }
        }
 
        public bool CanTransformMultipleBlocks {
            get { return(false); } 
        } 

        public virtual bool CanReuseTransform { 
            get { return(true); }
        }

        [System.Security.SecuritySafeCritical]  // auto-generated 
        public int TransformBlock(byte[] inputBuffer, int inputOffset, int inputCount, byte[] outputBuffer, int outputOffset) {
            // Do some validation 
            if (inputBuffer == null) throw new ArgumentNullException("inputBuffer"); 
            if (inputOffset < 0) throw new ArgumentOutOfRangeException("inputOffset", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
            if (inputCount < 0 || (inputCount > inputBuffer.Length)) throw new ArgumentException(Environment.GetResourceString("Argument_InvalidValue")); 
            if ((inputBuffer.Length - inputCount) < inputOffset) throw new ArgumentException(Environment.GetResourceString("Argument_InvalidOffLen"));
            Contract.EndContractBlock();

            if (_inputBuffer == null) 
                throw new ObjectDisposedException(null, Environment.GetResourceString("ObjectDisposed_Generic"));
 
            byte[] temp = new byte[inputCount]; 
            char[] tempChar;
            int effectiveCount; 

            if (_whitespaces == FromBase64TransformMode.IgnoreWhiteSpaces) {
                temp = DiscardWhiteSpaces(inputBuffer, inputOffset, inputCount);
                effectiveCount = temp.Length; 
            } else {
                Buffer.InternalBlockCopy(inputBuffer, inputOffset, temp, 0, inputCount); 
                effectiveCount = inputCount; 
            }
 
            if (effectiveCount + _inputIndex < 4) {
                Buffer.InternalBlockCopy(temp, 0, _inputBuffer, _inputIndex, effectiveCount);
                _inputIndex += effectiveCount;
                return 0; 
            }
 
            // Get the number of 4 bytes blocks to transform 
            int numBlocks = (effectiveCount + _inputIndex) / 4;
            byte[] transformBuffer = new byte[_inputIndex + effectiveCount]; 
            Buffer.InternalBlockCopy(_inputBuffer, 0, transformBuffer, 0, _inputIndex);
            Buffer.InternalBlockCopy(temp, 0, transformBuffer, _inputIndex, effectiveCount);
            _inputIndex = (effectiveCount + _inputIndex) % 4;
            Buffer.InternalBlockCopy(temp, effectiveCount - _inputIndex, _inputBuffer, 0, _inputIndex); 

#if !SILVERLIGHT 
            tempChar = Encoding.ASCII.GetChars(transformBuffer, 0, 4*numBlocks); 
#else // !SILVERLIGHT
            tempChar = Encoding.UTF8.GetChars(transformBuffer, 0, 4 * numBlocks); 
#endif // !SILVERLIGHT

            byte[] tempBytes = Convert.FromBase64CharArray(tempChar, 0, 4*numBlocks);
            Buffer.BlockCopy(tempBytes, 0, outputBuffer, outputOffset, tempBytes.Length); 
            return(tempBytes.Length);
        } 
 
        [System.Security.SecuritySafeCritical]  // auto-generated
        public byte[] TransformFinalBlock(byte[] inputBuffer, int inputOffset, int inputCount) { 
            // Do some validation
            if (inputBuffer == null) throw new ArgumentNullException("inputBuffer");
            if (inputOffset < 0) throw new ArgumentOutOfRangeException("inputOffset", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
            if (inputCount < 0 || (inputCount > inputBuffer.Length)) throw new ArgumentException(Environment.GetResourceString("Argument_InvalidValue")); 
            if ((inputBuffer.Length - inputCount) < inputOffset) throw new ArgumentException(Environment.GetResourceString("Argument_InvalidOffLen"));
            Contract.EndContractBlock(); 
 
            if (_inputBuffer == null)
                throw new ObjectDisposedException(null, Environment.GetResourceString("ObjectDisposed_Generic")); 

            byte[] temp = new byte[inputCount];
            char[] tempChar;
            int effectiveCount; 

            if (_whitespaces == FromBase64TransformMode.IgnoreWhiteSpaces) { 
                temp = DiscardWhiteSpaces(inputBuffer, inputOffset, inputCount); 
                effectiveCount = temp.Length;
            } else { 
                Buffer.InternalBlockCopy(inputBuffer, inputOffset, temp, 0, inputCount);
                effectiveCount = inputCount;
            }
 
            if (effectiveCount + _inputIndex < 4) {
                Reset(); 
                return (new byte[0]); 
            }
 
            // Get the number of 4 bytes blocks to transform
            int numBlocks = (effectiveCount + _inputIndex) / 4;
            byte[] transformBuffer = new byte[_inputIndex + effectiveCount];
            Buffer.InternalBlockCopy(_inputBuffer, 0, transformBuffer, 0, _inputIndex); 
            Buffer.InternalBlockCopy(temp, 0, transformBuffer, _inputIndex, effectiveCount);
            _inputIndex = (effectiveCount + _inputIndex) % 4; 
            Buffer.InternalBlockCopy(temp, effectiveCount - _inputIndex, _inputBuffer, 0, _inputIndex); 

#if !SILVERLIGHT 
            tempChar = Encoding.ASCII.GetChars(transformBuffer, 0, 4*numBlocks);
#else // !SILVERLIGHT
            tempChar = Encoding.UTF8.GetChars(transformBuffer, 0, 4 * numBlocks);
#endif // !SILVERLIGHT 

            byte[] tempBytes = Convert.FromBase64CharArray(tempChar, 0, 4*numBlocks); 
            // reinitialize the transform 
            Reset();
            return(tempBytes); 
        }

        private byte[] DiscardWhiteSpaces(byte[] inputBuffer, int inputOffset, int inputCount) {
            int i, iCount = 0; 
            for (i=0; i
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