//------------------------------------------------------------ // 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++]; } } } }