Psha1DerivedKeyGenerator.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / WCF / IdentityModel / System / IdentityModel / Psha1DerivedKeyGenerator.cs / 1305376 / Psha1DerivedKeyGenerator.cs
                        
                        
                            //------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------

namespace System.IdentityModel 
{
    using System; 
    using System.IO; 
    using System.Security.Cryptography;
    using System.Text; 
    using System.ServiceModel.Diagnostics;

    sealed class Psha1DerivedKeyGenerator
    { 
        byte[] key;
 
        public Psha1DerivedKeyGenerator(byte[] key) 
        {
            if (key == null) 
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull("key");
            }
            this.key = key; 
        }
 
        public byte[] GenerateDerivedKey(byte[] label, byte[] nonce, int derivedKeySize, int position) 
        {
            if (label == null) 
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull("label");
            }
            if (nonce == null) 
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull("nonce"); 
            } 
            ManagedPsha1 dkcp = new ManagedPsha1(key, label, nonce);
            return dkcp.GetDerivedKey(derivedKeySize, position); 
        }

        // private class to do the real work
        // Note: Though named ManagedPsha1, this works for both fips and non-fips compliance 
        sealed class ManagedPsha1
        { 
            byte[] aValue; 
            byte[] buffer;
            byte[] chunk; 
            KeyedHashAlgorithm hmac;
            int index;
            int position;
            byte[] secret; 
            byte[] seed;
 
            // assume arguments are already validated 
            public ManagedPsha1(byte[] secret, byte[] label, byte[] seed)
            { 
                this.secret = secret;
                this.seed = DiagnosticUtility.Utility.AllocateByteArray(checked(label.Length + seed.Length));
                label.CopyTo(this.seed, 0);
                seed.CopyTo(this.seed, label.Length); 

                this.aValue = this.seed; 
                this.chunk = new byte[0]; 
                this.index = 0;
                this.position = 0; 
                this.hmac = CryptoHelper.NewHmacSha1KeyedHashAlgorithm(secret);

                this.buffer = DiagnosticUtility.Utility.AllocateByteArray(checked(this.hmac.HashSize / 8 + this.seed.Length));
            } 

            public byte[] GetDerivedKey(int derivedKeySize, int position) 
            { 
                if (derivedKeySize < 0)
                { 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("derivedKeySize", SR.GetString(SR.ValueMustBeNonNegative)));
                }
                if (this.position > position)
                { 
                    throw  DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("position", SR.GetString(SR.ValueMustBeInRange, 0, this.position)));
                } 
 
                // Seek to the desired position in the pseudo-random stream.
                while (this.position < position) 
                {
                    GetByte();
                }
                int sizeInBytes = derivedKeySize / 8; 
                byte[] derivedKey = new byte[sizeInBytes];
                for (int i = 0; i < sizeInBytes; i++) 
                { 
                    derivedKey[i] = GetByte();
                } 
                return derivedKey;
            }

            byte GetByte() 
            {
                if (index >= chunk.Length) 
                { 
                    // Calculate A(i) = HMAC_SHA1(secret, A(i-1)).
                    hmac.Initialize(); 
                    this.aValue = hmac.ComputeHash(this.aValue);
                    // Calculate P_SHA1(secret, seed)[j] = HMAC_SHA1(secret, A(j+1) || seed).
                    this.aValue.CopyTo(buffer, 0);
                    this.seed.CopyTo(buffer, this.aValue.Length); 
                    hmac.Initialize();
                    this.chunk = hmac.ComputeHash(buffer); 
                    index = 0; 
                }
                position++; 
                return chunk[index++];
            }
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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Psha1DerivedKeyGenerator.cs source code in C# .NET

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