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// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
// <OWNER>[....]</OWNER>
//
//
// TripleDESCryptoServiceProvider.cs
//
namespace System.Security.Cryptography {
[System.Runtime.InteropServices.ComVisible(true)]
public sealed class TripleDESCryptoServiceProvider : TripleDES {
//
// public constructors
//
[System.Security.SecuritySafeCritical] // auto-generated
public TripleDESCryptoServiceProvider () {
if (!Utils.HasAlgorithm(Constants.CALG_3DES, 0))
throw new CryptographicException(Environment.GetResourceString("Cryptography_CSP_AlgorithmNotAvailable"));
// Since the CSP only supports a CFB feedback of 8, make that the default
FeedbackSizeValue = 8;
}
//
// public methods
//
[System.Security.SecuritySafeCritical] // auto-generated
public override ICryptoTransform CreateEncryptor (byte[] rgbKey, byte[] rgbIV) {
if (IsWeakKey(rgbKey))
throw new CryptographicException(Environment.GetResourceString("Cryptography_InvalidKey_Weak"),"TripleDES");
#if MONO
return new TripleDESTransform (this, true, rgbKey, rgbIV);
#else
return _NewEncryptor(rgbKey, ModeValue, rgbIV, FeedbackSizeValue, CryptoAPITransformMode.Encrypt);
#endif
}
[System.Security.SecuritySafeCritical] // auto-generated
public override ICryptoTransform CreateDecryptor (byte[] rgbKey, byte[] rgbIV) {
if (IsWeakKey(rgbKey))
throw new CryptographicException(Environment.GetResourceString("Cryptography_InvalidKey_Weak"),"TripleDES");
#if MONO
return new TripleDESTransform (this, false, rgbKey, rgbIV);
#else
return _NewEncryptor(rgbKey, ModeValue, rgbIV, FeedbackSizeValue, CryptoAPITransformMode.Decrypt);
#endif
}
public override void GenerateKey () {
KeyValue = new byte[KeySizeValue/8];
Utils.StaticRandomNumberGenerator.GetBytes(KeyValue);
// Never hand back a weak or semi-weak key
while (TripleDES.IsWeakKey(KeyValue)) {
Utils.StaticRandomNumberGenerator.GetBytes(KeyValue);
}
}
public override void GenerateIV () {
// IV is always 8 bytes/64 bits because block size is always 64 bits
IVValue = new byte[8];
Utils.StaticRandomNumberGenerator.GetBytes(IVValue);
}
//
// private methods
//
#if !MONO
[System.Security.SecurityCritical] // auto-generated
private ICryptoTransform _NewEncryptor (byte[] rgbKey, CipherMode mode, byte[] rgbIV, int feedbackSize, CryptoAPITransformMode encryptMode) {
int cArgs = 0;
int[] rgArgIds = new int[10];
Object[] rgArgValues = new Object[10];
int algid = Constants.CALG_3DES;
// Check for bad values
// 1) we don't support OFB mode in TripleDESCryptoServiceProvider
if (mode == CipherMode.OFB)
throw new CryptographicException(Environment.GetResourceString("Cryptography_CSP_OFBNotSupported"));
// 2) we only support CFB with a feedback size of 8 bits
if ((mode == CipherMode.CFB) && (feedbackSize != 8))
throw new CryptographicException(Environment.GetResourceString("Cryptography_CSP_CFBSizeNotSupported"));
// Build the key if one does not already exist
if (rgbKey == null) {
rgbKey = new byte[KeySizeValue/8];
Utils.StaticRandomNumberGenerator.GetBytes(rgbKey);
}
// Set the mode for the encryptor (defaults to CBC)
if (mode != CipherMode.CBC) {
rgArgIds[cArgs] = Constants.KP_MODE;
rgArgValues[cArgs] = mode;
cArgs += 1;
}
// If not ECB mode -- pass in an IV
if (mode != CipherMode.ECB) {
if (rgbIV == null) {
rgbIV = new byte[8];
Utils.StaticRandomNumberGenerator.GetBytes(rgbIV);
}
//
// We truncate IV's that are longer than the block size to 8 bytes : this is
// done to maintain backward compatibility with the behavior shipped in V1.x.
// The call to set the IV in CryptoAPI will ignore any bytes after the first 8
// bytes. We'll still reject IV's that are shorter than the block size though.
//
if (rgbIV.Length < 8)
throw new CryptographicException(Environment.GetResourceString("Cryptography_InvalidIVSize"));
rgArgIds[cArgs] = Constants.KP_IV;
rgArgValues[cArgs] = rgbIV;
cArgs += 1;
}
// If doing OFB or CFB, then we need to set the feed back loop size
if ((mode == CipherMode.OFB) || (mode == CipherMode.CFB)) {
rgArgIds[cArgs] = Constants.KP_MODE_BITS;
rgArgValues[cArgs] = feedbackSize;
cArgs += 1;
}
// If the size of rgbKey is 16 bytes, then we're doing two-key 3DES, so switch algids
// Note that we assume that if a CSP supports CALG_3DES then it also supports CALG_3DES_112
if (rgbKey.Length == 16) {
algid = Constants.CALG_3DES_112;
}
// Create the encryptor object
return new CryptoAPITransform(algid, cArgs, rgArgIds,
rgArgValues, rgbKey, PaddingValue,
mode, BlockSizeValue, feedbackSize, false,
encryptMode);
}
#endif
}
}
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