RSAPKCS1SignatureDeformatter.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / Security / Cryptography / RSAPKCS1SignatureDeformatter.cs / 1305376 / RSAPKCS1SignatureDeformatter.cs
                        

                        
                            using System.Diagnostics.Contracts; 
// ==++==
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// ==--==
// [....] 
// 

// 
// RSAPKCS1SignatureDeformatter.cs
//

namespace System.Security.Cryptography { 
    [System.Runtime.InteropServices.ComVisible(true)]
    public class RSAPKCS1SignatureDeformatter : AsymmetricSignatureDeformatter { 
        // 
        //  This class provides the PKCS#1 v1.5 signature format processing during
        //  the verification process (i.e. decrypting the object).  The class has 
        //  some special code for dealing with the CSP based RSA keys as the
        //  formatting and verification is done within the CSP rather than in
        //  managed code.
        // 

        private RSA    _rsaKey; // RSA Key value to do decrypt operation 
        private String _strOID; // OID value for the HASH algorithm 

        // 
        // public constructors
        //

        public RSAPKCS1SignatureDeformatter() {} 
        public RSAPKCS1SignatureDeformatter(AsymmetricAlgorithm key) {
            if (key == null) 
                throw new ArgumentNullException("key"); 
            Contract.EndContractBlock();
            _rsaKey = (RSA) key; 
        }

        //
        // public methods 
        //
 
        public override void SetKey(AsymmetricAlgorithm key) { 
            if (key == null)
                throw new ArgumentNullException("key"); 
            Contract.EndContractBlock();
            _rsaKey = (RSA) key;
        }
 
        public override void SetHashAlgorithm(String strName) {
            _strOID = CryptoConfig.MapNameToOID(strName); 
        } 

        [System.Security.SecuritySafeCritical]  // auto-generated 
        public override bool VerifySignature(byte[] rgbHash, byte[] rgbSignature) {
            if (rgbHash == null)
                throw new ArgumentNullException("rgbHash");
            if (rgbSignature == null) 
                throw new ArgumentNullException("rgbSignature");
            Contract.EndContractBlock(); 
 
            if (_strOID == null)
                throw new CryptographicUnexpectedOperationException(Environment.GetResourceString("Cryptography_MissingOID")); 
            if (_rsaKey == null)
                throw new CryptographicUnexpectedOperationException(Environment.GetResourceString("Cryptography_MissingKey"));

            // Two cases here -- if we are talking to the CSP version or if we are talking to some other RSA provider. 
            if (_rsaKey is RSACryptoServiceProvider) {
                return ((RSACryptoServiceProvider) _rsaKey).VerifyHash(rgbHash, _strOID, rgbSignature); 
            } 
            else {
                byte[] pad = Utils.RsaPkcs1Padding(_rsaKey, CryptoConfig.EncodeOID(_strOID), rgbHash); 
                // Apply the public key to the signature data to get back the padded buffer actually signed.
                // Compare the two buffers to see if they match; ignoring any leading zeros
                return Utils.CompareBigIntArrays(_rsaKey.EncryptValue(rgbSignature), pad);
            } 
        }
    } 
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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