1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
|
//------------------------------------------------------------------------------
// <copyright file="CryptographicKey.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Web.Security.Cryptography {
using System;
using System.Web.Util;
// Represents a key that can be used for a cryptographic operation.
internal sealed class CryptographicKey {
private readonly byte[] _keyMaterial;
public CryptographicKey(byte[] keyMaterial) {
_keyMaterial = keyMaterial;
}
// Returns the length of the key (in bits).
public int KeyLength {
get {
return checked(_keyMaterial.Length * 8);
}
}
// Extracts the specified number of bits at the specified offset
// and returns a new CryptographicKey. This is not appropriate
// for subkey derivation, but it can be used if this cryptographic
// key is actually two keys (like encryption + validation)
// concatenated together. Inputs are specified as bit lengths.
public CryptographicKey ExtractBits(int offset, int count) {
Debug.Assert(offset % 8 == 0, "Offset must be divisible by 8.");
Debug.Assert(count % 8 == 0, "Count must be divisible by 8.");
int offsetBytes = offset / 8;
int countBytes = count / 8;
byte[] newKey = new byte[countBytes];
Buffer.BlockCopy(_keyMaterial, offsetBytes, newKey, 0, countBytes);
return new CryptographicKey(newKey);
}
// Returns the raw key material as a byte array.
public byte[] GetKeyMaterial() {
return _keyMaterial;
}
}
}
|
