Code:
/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / clr / src / BCL / System / Security / Cryptography / RC2CryptoServiceProvider.cs / 1 / RC2CryptoServiceProvider.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // // RC2CryptoServiceProvider.cs // namespace System.Security.Cryptography { using System.Globalization; [System.Runtime.InteropServices.ComVisible(true)] public sealed class RC2CryptoServiceProvider : RC2 { private bool m_use40bitSalt = false; private static KeySizes[] s_legalKeySizes = { new KeySizes(40, 128, 8) // cryptoAPI implementation only goes up to 128 }; // // public constructors // public RC2CryptoServiceProvider () { if (Utils.FipsAlgorithmPolicy == 1) throw new InvalidOperationException(Environment.GetResourceString("Cryptography_NonCompliantFIPSAlgorithm")); if (!Utils.HasAlgorithm(Constants.CALG_RC2, 0)) throw new CryptographicException(Environment.GetResourceString("Cryptography_CSP_AlgorithmNotAvailable")); // Acquire a Type 1 provider. This will be the Enhanced provider if available, otherwise // it will be the base provider. LegalKeySizesValue = s_legalKeySizes; // Since the CSP only supports a CFB feedback of 8, make that the default FeedbackSizeValue = 8; } // // public methods // public override int EffectiveKeySize { get { return KeySizeValue; } set { if (value != KeySizeValue) throw new CryptographicUnexpectedOperationException(Environment.GetResourceString("Cryptography_RC2_EKSKS2")); } } [System.Runtime.InteropServices.ComVisible(false)] public bool UseSalt { get { return m_use40bitSalt; } set { m_use40bitSalt = value; } } public override ICryptoTransform CreateEncryptor (byte[] rgbKey, byte[] rgbIV) { return _NewEncryptor(rgbKey, ModeValue, rgbIV, EffectiveKeySizeValue, FeedbackSizeValue, CryptoAPITransformMode.Encrypt); } public override ICryptoTransform CreateDecryptor (byte[] rgbKey, byte[] rgbIV) { return _NewEncryptor(rgbKey, ModeValue, rgbIV, EffectiveKeySizeValue, FeedbackSizeValue, CryptoAPITransformMode.Decrypt); } public override void GenerateKey () { KeyValue = new byte[KeySizeValue/8]; Utils.StaticRandomNumberGenerator.GetBytes(KeyValue); } public override void GenerateIV () { // block size is always 64 bits so IV is always 64 bits == 8 bytes IVValue = new byte[8]; Utils.StaticRandomNumberGenerator.GetBytes(IVValue); } // // private methods // private ICryptoTransform _NewEncryptor (byte[] rgbKey, CipherMode mode, byte[] rgbIV, int effectiveKeySize, int feedbackSize, CryptoAPITransformMode encryptMode) { int cArgs = 0; int[] rgArgIds = new int[10]; Object[] rgArgValues = new Object[10]; // Check for bad values // 1) we don't support OFB mode in RC2_CSP 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")); if (rgbKey == null) { rgbKey = new byte[KeySizeValue/8]; Utils.StaticRandomNumberGenerator.GetBytes(rgbKey); } // Check the rgbKey size int keySizeValue = rgbKey.Length * 8; if (!ValidKeySize(keySizeValue)) throw new CryptographicException(Environment.GetResourceString("Cryptography_InvalidKeySize")); // Deal with effective key length questions rgArgIds[cArgs] = Constants.KP_EFFECTIVE_KEYLEN; if (EffectiveKeySizeValue == 0) { rgArgValues[cArgs] = keySizeValue; } else { rgArgValues[cArgs] = effectiveKeySize; } cArgs += 1; // 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 (!Utils.HasAlgorithm(Constants.CALG_RC2, keySizeValue)) throw new CryptographicException(String.Format(CultureInfo.CurrentCulture, Environment.GetResourceString("Cryptography_CSP_AlgKeySizeNotAvailable"), keySizeValue)); // Create the encryptor/decryptor object return new CryptoAPITransform(Constants.CALG_RC2, cArgs, rgArgIds, rgArgValues, rgbKey, PaddingValue, mode, BlockSizeValue, feedbackSize, m_use40bitSalt, encryptMode); } } }
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