52 lines
1.9 KiB
C#
52 lines
1.9 KiB
C#
//------------------------------------------------------------------------------
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// <copyright file="CryptographicKey.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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//------------------------------------------------------------------------------
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namespace System.Web.Security.Cryptography {
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using System;
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using System.Web.Util;
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// Represents a key that can be used for a cryptographic operation.
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internal sealed class CryptographicKey {
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private readonly byte[] _keyMaterial;
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public CryptographicKey(byte[] keyMaterial) {
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_keyMaterial = keyMaterial;
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}
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// Returns the length of the key (in bits).
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public int KeyLength {
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get {
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return checked(_keyMaterial.Length * 8);
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}
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}
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// Extracts the specified number of bits at the specified offset
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// and returns a new CryptographicKey. This is not appropriate
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// for subkey derivation, but it can be used if this cryptographic
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// key is actually two keys (like encryption + validation)
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// concatenated together. Inputs are specified as bit lengths.
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public CryptographicKey ExtractBits(int offset, int count) {
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Debug.Assert(offset % 8 == 0, "Offset must be divisible by 8.");
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Debug.Assert(count % 8 == 0, "Count must be divisible by 8.");
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int offsetBytes = offset / 8;
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int countBytes = count / 8;
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byte[] newKey = new byte[countBytes];
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Buffer.BlockCopy(_keyMaterial, offsetBytes, newKey, 0, countBytes);
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return new CryptographicKey(newKey);
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}
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// Returns the raw key material as a byte array.
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public byte[] GetKeyMaterial() {
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return _keyMaterial;
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}
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}
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}
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