-
Notifications
You must be signed in to change notification settings - Fork 50
/
EtM_CBC.cs
224 lines (195 loc) · 10.9 KB
/
EtM_CBC.cs
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
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
using System;
using System.Runtime.CompilerServices;
using System.Security.Cryptography;
using System.Threading;
namespace SecurityDriven.Inferno
{
public static partial class EtM_CBC
{
static readonly Func<Aes> _aesFactory = Cipher.AesFactories.Aes;
static readonly Func<Mac.HMAC2> _hmacFactory = Mac.HMACFactories.HMACSHA384;
static readonly CryptoRandom _cryptoRandom = new CryptoRandom();
const int AES_IV_LENGTH = Cipher.AesConstants.AES_BLOCK_SIZE;
const int MAC_LENGTH = 16;
const int MAC_KEY_LENGTH = MAC_LENGTH;
const int ENC_KEY_LENGTH = 32;
static readonly int HMAC_LENGTH = _hmacFactory().HashSize / 8;
static readonly int CONTEXT_TWEAK_LENGTH = Math.Max(ENC_KEY_LENGTH - AES_IV_LENGTH, 0);
static readonly int CONTEXT_BUFFER_LENGTH = CONTEXT_TWEAK_LENGTH + AES_IV_LENGTH;
static readonly ThreadLocal<byte[]> _iv = new ThreadLocal<byte[]>(() => new byte[AES_IV_LENGTH]);
static readonly ThreadLocal<byte[]> _contextBuffer = new ThreadLocal<byte[]>(() => new byte[CONTEXT_BUFFER_LENGTH]);
static readonly ThreadLocal<byte[]> _encKey = new ThreadLocal<byte[]>(() => new byte[ENC_KEY_LENGTH]);
static readonly ThreadLocal<byte[]> _macKey = new ThreadLocal<byte[]>(() => new byte[MAC_KEY_LENGTH]);
static readonly ThreadLocal<byte[]> _sessionKey = new ThreadLocal<byte[]>(() => new byte[HMAC_LENGTH]);
public static int CalculateCiphertextLength(ArraySegment<byte> plaintext)
{
int finalBlockLength = plaintext.Count - (plaintext.Count & (-Cipher.AesConstants.AES_BLOCK_SIZE));
int paddingLength = AES_IV_LENGTH - finalBlockLength;
return CONTEXT_BUFFER_LENGTH + plaintext.Count + paddingLength + MAC_LENGTH;
}
static void ValidateAes(Aes aes) // detect & fix any Mode/Padding deviation
{
if (aes.Mode == CipherMode.CBC && aes.Padding == PaddingMode.PKCS7) return;
aes.Mode = CipherMode.CBC;
aes.Padding = PaddingMode.PKCS7;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
static void ClearKeyMaterial()
{
Array.Clear(_encKey.Value, 0, ENC_KEY_LENGTH);
Array.Clear(_macKey.Value, 0, MAC_KEY_LENGTH);
Array.Clear(_sessionKey.Value, 0, HMAC_LENGTH);
}
public static void Encrypt(byte[] masterKey, ArraySegment<byte> plaintext, byte[] output, int outputOffset, ArraySegment<byte>? salt = null, uint counter = 1)
{
int fullBlockLength = plaintext.Count & (-Cipher.AesConstants.AES_BLOCK_SIZE);
int finalBlockLength = plaintext.Count % Cipher.AesConstants.AES_BLOCK_SIZE;
int paddingLength = Cipher.AesConstants.AES_BLOCK_SIZE - finalBlockLength;
int ciphertextLength = CONTEXT_BUFFER_LENGTH + plaintext.Count + paddingLength + MAC_LENGTH;
if (output.Length - outputOffset < ciphertextLength) throw new ArgumentOutOfRangeException(nameof(output), $"'{nameof(output)}' array segment is not big enough for the ciphertext");
try
{
var iv = _iv.Value;
var contextBuffer = _contextBuffer.Value;
var encKey = _encKey.Value;
var macKey = _macKey.Value;
var sessionKey = _sessionKey.Value;
using (var aes = _aesFactory())
{
EtM_CBC.ValidateAes(aes);
_cryptoRandom.NextBytes(contextBuffer, 0, CONTEXT_BUFFER_LENGTH);
Utils.BlockCopy(contextBuffer, CONTEXT_TWEAK_LENGTH, iv, 0, AES_IV_LENGTH);
Kdf.SP800_108_Ctr.DeriveKey(hmacFactory: _hmacFactory, key: masterKey, label: salt, context: contextBuffer.AsArraySegment(), derivedOutput: sessionKey.AsArraySegment(), counter: counter);
Utils.BlockCopy(sessionKey, 0, macKey, 0, MAC_KEY_LENGTH);
Utils.BlockCopy(sessionKey, MAC_KEY_LENGTH, encKey, 0, ENC_KEY_LENGTH);
Utils.BlockCopy(contextBuffer, 0, output, outputOffset, CONTEXT_BUFFER_LENGTH);
using (var aesEncryptor = aes.CreateEncryptor(encKey, iv))
{
if (fullBlockLength > 0)
aesEncryptor.TransformBlock(inputBuffer: plaintext.Array, inputOffset: plaintext.Offset, inputCount: fullBlockLength, outputBuffer: output, outputOffset: outputOffset + CONTEXT_BUFFER_LENGTH);
var finalBlockBuffer = aesEncryptor.TransformFinalBlock(inputBuffer: plaintext.Array, inputOffset: plaintext.Offset + fullBlockLength, inputCount: finalBlockLength);
Utils.BlockCopy(finalBlockBuffer, 0, output, outputOffset + CONTEXT_BUFFER_LENGTH + fullBlockLength, finalBlockBuffer.Length);
}// using aesEncryptor
}// using aes
using (var hmac = _hmacFactory())
{
hmac.Key = macKey;
hmac.TransformBlock(output, outputOffset + CONTEXT_TWEAK_LENGTH, AES_IV_LENGTH + plaintext.Count + paddingLength, null, 0);
hmac.TransformFinalBlock(output, 0, 0);
var fullmac = hmac.HashInner;
Utils.BlockCopy(fullmac, 0, output, outputOffset + ciphertextLength - MAC_LENGTH, MAC_LENGTH);
}// using hmac
}
finally { EtM_CBC.ClearKeyMaterial(); }
}// Encrypt()
public static byte[] Encrypt(byte[] masterKey, ArraySegment<byte> plaintext, ArraySegment<byte>? salt = null, uint counter = 1)
{
//int fullBlockLength = plaintext.Count & (-Cipher.AesConstants.AES_BLOCK_SIZE);
int finalBlockLength = plaintext.Count % Cipher.AesConstants.AES_BLOCK_SIZE;
int paddingLength = Cipher.AesConstants.AES_BLOCK_SIZE - finalBlockLength;
int ciphertextLength = CONTEXT_BUFFER_LENGTH + plaintext.Count + paddingLength + MAC_LENGTH;
byte[] buffer = new byte[ciphertextLength];
EtM_CBC.Encrypt(masterKey: masterKey, plaintext: plaintext, output: buffer, outputOffset: 0, salt: salt, counter: counter);
return buffer;
}// Encrypt()
public static void Decrypt(byte[] masterKey, ArraySegment<byte> ciphertext, ref ArraySegment<byte>? outputSegment, ArraySegment<byte>? salt = null, uint counter = 1)
{
int cipherLength = ciphertext.Count - CONTEXT_BUFFER_LENGTH - MAC_LENGTH;
if (cipherLength < Cipher.AesConstants.AES_BLOCK_SIZE) { outputSegment = null; return; }
int fullBlockLength = cipherLength - AES_IV_LENGTH;
byte[] finalBlock = null;
try
{
var iv = _iv.Value;
var encKey = _encKey.Value;
var macKey = _macKey.Value;
var sessionKey = _sessionKey.Value;
Kdf.SP800_108_Ctr.DeriveKey(hmacFactory: _hmacFactory, key: masterKey, label: salt, context: new ArraySegment<byte>(ciphertext.Array, ciphertext.Offset, CONTEXT_BUFFER_LENGTH), derivedOutput: sessionKey.AsArraySegment(), counter: counter);
Utils.BlockCopy(sessionKey, 0, macKey, 0, MAC_KEY_LENGTH);
using (var hmac = _hmacFactory())
{
hmac.Key = macKey;
hmac.TransformBlock(ciphertext.Array, ciphertext.Offset + CONTEXT_TWEAK_LENGTH, AES_IV_LENGTH + cipherLength, null, 0);
hmac.TransformFinalBlock(ciphertext.Array, 0, 0);
var fullmacActual = hmac.HashInner;
if (!Utils.ConstantTimeEqual(fullmacActual, 0, ciphertext.Array, ciphertext.Offset + ciphertext.Count - MAC_LENGTH, MAC_LENGTH)) { outputSegment = null; return; };
}// using hmac
Utils.BlockCopy(ciphertext.Array, ciphertext.Offset + CONTEXT_TWEAK_LENGTH, iv, 0, AES_IV_LENGTH);
Utils.BlockCopy(sessionKey, MAC_KEY_LENGTH, encKey, 0, ENC_KEY_LENGTH);
using (var aes = _aesFactory())
{
EtM_CBC.ValidateAes(aes);
using (var aesDecryptor = aes.CreateDecryptor(encKey, iv))
{
int fullBlockTransformed = 0;
if (fullBlockLength > 0)
fullBlockTransformed = aesDecryptor.TransformBlock(inputBuffer: ciphertext.Array, inputOffset: ciphertext.Offset + CONTEXT_BUFFER_LENGTH, inputCount: fullBlockLength, outputBuffer: outputSegment.Value.Array, outputOffset: outputSegment.Value.Offset);
finalBlock = aesDecryptor.TransformFinalBlock(ciphertext.Array, ciphertext.Offset + CONTEXT_BUFFER_LENGTH + fullBlockLength, cipherLength - fullBlockLength);
Utils.BlockCopy(finalBlock, 0, outputSegment.Value.Array, outputSegment.Value.Offset + fullBlockTransformed, finalBlock.Length);
outputSegment = new ArraySegment<byte>?(new ArraySegment<byte>(outputSegment.Value.Array, outputSegment.Value.Offset, fullBlockTransformed + finalBlock.Length));
}// using aesDecryptor
}// using aes
}
finally
{
EtM_CBC.ClearKeyMaterial();
if (finalBlock != null) Array.Clear(finalBlock, 0, finalBlock.Length);
}
}// Decrypt()
public static byte[] Decrypt(byte[] masterKey, ArraySegment<byte> ciphertext, ArraySegment<byte>? salt = null, uint counter = 1)
{
int cipherLength = ciphertext.Count - CONTEXT_BUFFER_LENGTH - MAC_LENGTH;
if (cipherLength < Cipher.AesConstants.AES_BLOCK_SIZE) return null;
try
{
var iv = _iv.Value;
var encKey = _encKey.Value;
var macKey = _macKey.Value;
var sessionKey = _sessionKey.Value;
Kdf.SP800_108_Ctr.DeriveKey(hmacFactory: _hmacFactory, key: masterKey, label: salt, context: new ArraySegment<byte>(ciphertext.Array, ciphertext.Offset, CONTEXT_BUFFER_LENGTH), derivedOutput: sessionKey.AsArraySegment(), counter: counter);
Utils.BlockCopy(sessionKey, 0, macKey, 0, MAC_KEY_LENGTH);
using (var hmac = _hmacFactory())
{
hmac.Key = macKey;
hmac.TransformBlock(ciphertext.Array, ciphertext.Offset + CONTEXT_TWEAK_LENGTH, AES_IV_LENGTH + cipherLength, null, 0);
hmac.TransformFinalBlock(ciphertext.Array, 0, 0);
var fullmacActual = hmac.HashInner;
if (!Utils.ConstantTimeEqual(fullmacActual, 0, ciphertext.Array, ciphertext.Offset + ciphertext.Count - MAC_LENGTH, MAC_LENGTH)) return null;
}// using hmac
Utils.BlockCopy(ciphertext.Array, ciphertext.Offset + CONTEXT_TWEAK_LENGTH, iv, 0, AES_IV_LENGTH);
Utils.BlockCopy(sessionKey, MAC_KEY_LENGTH, encKey, 0, ENC_KEY_LENGTH);
using (var aes = _aesFactory())
{
EtM_CBC.ValidateAes(aes);
using (var aesDecryptor = aes.CreateDecryptor(encKey, iv))
{
return aesDecryptor.TransformFinalBlock(ciphertext.Array, ciphertext.Offset + CONTEXT_BUFFER_LENGTH, cipherLength);
}// using aesDecryptor
}// using aes
}
finally { EtM_CBC.ClearKeyMaterial(); }
}// Decrypt()
public static bool Authenticate(byte[] masterKey, ArraySegment<byte> ciphertext, ArraySegment<byte>? salt = null, uint counter = 1)
{
int cipherLength = ciphertext.Count - CONTEXT_BUFFER_LENGTH - MAC_LENGTH;
if (cipherLength < Cipher.AesConstants.AES_BLOCK_SIZE) return false;
try
{
var macKey = _macKey.Value;
var sessionKey = _sessionKey.Value;
Kdf.SP800_108_Ctr.DeriveKey(hmacFactory: _hmacFactory, key: masterKey, label: salt, context: new ArraySegment<byte>(ciphertext.Array, ciphertext.Offset, CONTEXT_BUFFER_LENGTH), derivedOutput: sessionKey.AsArraySegment(), counter: counter);
Utils.BlockCopy(sessionKey, 0, macKey, 0, MAC_KEY_LENGTH);
using (var hmac = _hmacFactory())
{
hmac.Key = macKey;
hmac.TransformBlock(ciphertext.Array, ciphertext.Offset + CONTEXT_TWEAK_LENGTH, AES_IV_LENGTH + cipherLength, null, 0);
hmac.TransformFinalBlock(ciphertext.Array, 0, 0);
var fullmacActual = hmac.HashInner;
if (!Utils.ConstantTimeEqual(fullmacActual, 0, ciphertext.Array, ciphertext.Offset + ciphertext.Count - MAC_LENGTH, MAC_LENGTH)) return false;
}// using hmac
return true;
}
finally { EtM_CBC.ClearKeyMaterial(); }
}// Authenticate()
}//class EtM_CBC
}//ns