| public CalculateMac ( Org.BouncyCastle.Crypto.Tls.ContentType type, byte message, int offset, int len ) : byte[] | ||
| type | Org.BouncyCastle.Crypto.Tls.ContentType | |
| message | byte | |
| offset | int | |
| len | int | |
| Результат | byte[] | |
public virtual byte[] EncodePlaintext(ContentType type, byte[] plaintext, int offset, int len)
{
int blocksize = encryptCipher.GetBlockSize();
int padding_length = blocksize - 1 - ((len + wMac.Size) % blocksize);
//bool isTls = context.ServerVersion.FullVersion >= ProtocolVersion.TLSv10.FullVersion;
bool isTls = true;
if (isTls)
{
// Add a random number of extra blocks worth of padding
int maxExtraPadBlocks = (255 - padding_length) / blocksize;
int actualExtraPadBlocks = ChooseExtraPadBlocks(context.SecureRandom, maxExtraPadBlocks);
padding_length += actualExtraPadBlocks * blocksize;
}
int totalsize = len + wMac.Size + padding_length + 1;
byte[] outbuf = new byte[totalsize];
Array.Copy(plaintext, offset, outbuf, 0, len);
byte[] mac = wMac.CalculateMac(type, plaintext, offset, len);
Array.Copy(mac, 0, outbuf, len, mac.Length);
int paddoffset = len + mac.Length;
for (int i = 0; i <= padding_length; i++)
{
outbuf[i + paddoffset] = (byte)padding_length;
}
for (int i = 0; i < totalsize; i += blocksize)
{
encryptCipher.ProcessBlock(outbuf, i, outbuf, i);
}
return(outbuf);
}
internal override byte[] EncodePlaintext(
short type,
byte[] plaintext,
int offset,
int len)
{
int blocksize = encryptCipher.GetBlockSize();
int paddingsize = blocksize
- ((len + writeMac.Size + 1) % blocksize);
int totalsize = len + writeMac.Size + paddingsize + 1;
byte[] outbuf = new byte[totalsize];
Array.Copy(plaintext, offset, outbuf, 0, len);
byte[] mac = writeMac.CalculateMac(type, plaintext, offset, len);
Array.Copy(mac, 0, outbuf, len, mac.Length);
int paddoffset = len + mac.Length;
for (int i = 0; i <= paddingsize; i++)
{
outbuf[i + paddoffset] = (byte)paddingsize;
}
for (int i = 0; i < totalsize; i += blocksize)
{
encryptCipher.ProcessBlock(outbuf, i, outbuf, i);
}
return(outbuf);
}
public byte[] EncodePlaintext(short type, byte[] plaintext, int offset, int len)
{
int blocksize = encryptCipher.GetBlockSize();
// Add a random number of extra blocks worth of padding
int minPaddingSize = blocksize - ((len + writeMac.Size + 1) % blocksize);
int maxExtraPadBlocks = (255 - minPaddingSize) / blocksize;
int actualExtraPadBlocks = ChooseExtraPadBlocks(handler.Random, maxExtraPadBlocks);
int paddingsize = minPaddingSize + (actualExtraPadBlocks * blocksize);
int totalsize = len + writeMac.Size + paddingsize + 1;
byte[] outbuf = new byte[totalsize];
Array.Copy(plaintext, offset, outbuf, 0, len);
byte[] mac = writeMac.CalculateMac(type, plaintext, offset, len);
Array.Copy(mac, 0, outbuf, len, mac.Length);
int paddoffset = len + mac.Length;
for (int i = 0; i <= paddingsize; i++)
{
outbuf[i + paddoffset] = (byte)paddingsize;
}
for (int i = 0; i < totalsize; i += blocksize)
{
encryptCipher.ProcessBlock(outbuf, i, outbuf, i);
}
return(outbuf);
}
/// <exception cref="IOException"></exception>
public virtual byte[] DecodeCiphertext(long seqNo, byte type, byte[] ciphertext, int offset, int len)
{
if (readMac == null)
{
return(Arrays.CopyOfRange(ciphertext, offset, offset + len));
}
int macSize = readMac.Size;
if (len < macSize)
{
throw new TlsFatalAlert(AlertDescription.decode_error);
}
int macInputLen = len - macSize;
byte[] receivedMac = Arrays.CopyOfRange(ciphertext, offset + macInputLen, offset + len);
byte[] computedMac = readMac.CalculateMac(seqNo, type, ciphertext, offset, macInputLen);
if (!Arrays.ConstantTimeAreEqual(receivedMac, computedMac))
{
throw new TlsFatalAlert(AlertDescription.bad_record_mac);
}
return(Arrays.CopyOfRange(ciphertext, offset, offset + macInputLen));
}
protected virtual void CheckMac(long seqNo, byte type, byte[] recBuf, int recStart, int recEnd, byte[] calcBuf, int calcOff, int calcLen)
{
byte[] a = Arrays.CopyOfRange(recBuf, recStart, recEnd);
byte[] b = readMac.CalculateMac(seqNo, type, calcBuf, calcOff, calcLen);
if (!Arrays.ConstantTimeAreEqual(a, b))
{
throw new TlsFatalAlert(20);
}
}
/// <exception cref="IOException"></exception>
protected virtual void CheckMac(long seqNo, byte type, byte[] recBuf, int recStart, int recEnd, byte[] calcBuf, int calcOff, int calcLen)
{
byte[] receivedMac = Arrays.CopyOfRange(recBuf, recStart, recEnd);
byte[] computedMac = readMac.CalculateMac(seqNo, type, calcBuf, calcOff, calcLen);
if (!Arrays.ConstantTimeAreEqual(receivedMac, computedMac))
{
throw new TlsFatalAlert(AlertDescription.bad_record_mac);
}
}
public byte[] EncodePlaintext(byte type, byte[] plaintext, int offset, int len)
{
byte[] mac = writeMac.CalculateMac(type, plaintext, offset, len);
int size = len + mac.Length;
byte[] outbuf = new byte[size];
encryptCipher.ProcessBytes(plaintext, offset, len, outbuf, 0);
encryptCipher.ProcessBytes(mac, 0, mac.Length, outbuf, len);
return(outbuf);
}
public virtual byte[] EncodePlaintext(long seqNo, byte type, byte[] plaintext, int offset, int len)
{
if (usesNonce)
{
UpdateIV(encryptCipher, forEncryption: true, seqNo);
}
byte[] array = new byte[len + writeMac.Size];
encryptCipher.ProcessBytes(plaintext, offset, len, array, 0);
byte[] array2 = writeMac.CalculateMac(seqNo, type, plaintext, offset, len);
encryptCipher.ProcessBytes(array2, 0, array2.Length, array, len);
return(array);
}
public virtual byte[] EncodePlaintext(long seqNo, byte type, byte[] plaintext, int offset, int len)
{
if (writeMac == null)
{
return(Arrays.CopyOfRange(plaintext, offset, offset + len));
}
byte[] array = writeMac.CalculateMac(seqNo, type, plaintext, offset, len);
byte[] array2 = new byte[len + array.Length];
Array.Copy(plaintext, offset, array2, 0, len);
Array.Copy(array, 0, array2, len, array.Length);
return(array2);
}
/// <exception cref="IOException"></exception>
public virtual byte[] EncodePlaintext(long seqNo, byte type, byte[] plaintext, int offset, int len)
{
if (writeMac == null)
{
return(Arrays.CopyOfRange(plaintext, offset, offset + len));
}
byte[] mac = writeMac.CalculateMac(seqNo, type, plaintext, offset, len);
byte[] ciphertext = new byte[len + mac.Length];
Array.Copy(plaintext, offset, ciphertext, 0, len);
Array.Copy(mac, 0, ciphertext, len, mac.Length);
return(ciphertext);
}
public virtual byte[] EncodePlaintext(long seqNo, byte type, byte[] plaintext, int offset, int len)
{
if (usesNonce)
{
UpdateIV(encryptCipher, true, seqNo);
}
byte[] outBuf = new byte[len + writeMac.Size];
encryptCipher.ProcessBytes(plaintext, offset, len, outBuf, 0);
byte[] mac = writeMac.CalculateMac(seqNo, type, plaintext, offset, len);
encryptCipher.ProcessBytes(mac, 0, mac.Length, outBuf, len);
return(outBuf);
}
public byte[] DecodeCiphertext(byte type, byte[] ciphertext, int offset, int len)
{
byte[] deciphered = new byte[len];
decryptCipher.ProcessBytes(ciphertext, offset, len, deciphered, 0);
int plaintextSize = deciphered.Length - readMac.Size;
byte[] plainText = CopyData(deciphered, 0, plaintextSize);
byte[] receivedMac = CopyData(deciphered, plaintextSize, readMac.Size);
byte[] computedMac = readMac.CalculateMac(type, plainText, 0, plainText.Length);
if (!Arrays.ConstantTimeAreEqual(receivedMac, computedMac))
{
throw new TlsFatalAlert(AlertDescription.bad_record_mac);
}
return(plainText);
}
public virtual byte[] EncodePlaintext(long seqNo, byte type, byte[] plaintext, int offset, int len)
{
/*
* draft-josefsson-salsa20-tls-04 2.1 Note that Salsa20 requires a 64-bit nonce. That
* nonce is updated on the encryption of every TLS record, and is set to be the 64-bit TLS
* record sequence number. In case of DTLS the 64-bit nonce is formed as the concatenation
* of the 16-bit epoch with the 48-bit sequence number.
*/
if (usesNonce)
{
UpdateIV(encryptCipher, true, seqNo);
}
byte[] outBuf = new byte[len + writeMac.Size];
encryptCipher.ProcessBytes(plaintext, offset, len, outBuf, 0);
byte[] mac = writeMac.CalculateMac(seqNo, type, plaintext, offset, len);
encryptCipher.ProcessBytes(mac, 0, mac.Length, outBuf, len);
return(outBuf);
}
public virtual byte[] DecodeCiphertext(long seqNo, byte type, byte[] ciphertext, int offset, int len)
{
if (readMac == null)
{
return(Arrays.CopyOfRange(ciphertext, offset, offset + len));
}
int size = readMac.Size;
if (len < size)
{
throw new TlsFatalAlert(50);
}
int num = len - size;
byte[] a = Arrays.CopyOfRange(ciphertext, offset + num, offset + len);
byte[] b = readMac.CalculateMac(seqNo, type, ciphertext, offset, num);
if (!Arrays.ConstantTimeAreEqual(a, b))
{
throw new TlsFatalAlert(20);
}
return(Arrays.CopyOfRange(ciphertext, offset, offset + num));
}
public virtual byte[] DecodeCiphertext(long seqNo, byte type, byte[] ciphertext, int offset, int len)
{
int blockSize = decryptCipher.GetBlockSize();
int size = mReadMac.Size;
int num = blockSize;
num = ((!encryptThenMac) ? Math.Max(num, size + 1) : (num + size));
if (useExplicitIV)
{
num += blockSize;
}
if (len < num)
{
throw new TlsFatalAlert(50);
}
int num2 = len;
if (encryptThenMac)
{
num2 -= size;
}
if (num2 % blockSize != 0)
{
throw new TlsFatalAlert(21);
}
if (encryptThenMac)
{
int num3 = offset + len;
byte[] b = Arrays.CopyOfRange(ciphertext, num3 - size, num3);
byte[] a = mReadMac.CalculateMac(seqNo, type, ciphertext, offset, len - size);
if (!Arrays.ConstantTimeAreEqual(a, b))
{
throw new TlsFatalAlert(20);
}
}
if (useExplicitIV)
{
decryptCipher.Init(forEncryption: false, new ParametersWithIV(null, ciphertext, offset, blockSize));
offset += blockSize;
num2 -= blockSize;
}
for (int i = 0; i < num2; i += blockSize)
{
decryptCipher.ProcessBlock(ciphertext, offset + i, ciphertext, offset + i);
}
int num4 = CheckPaddingConstantTime(ciphertext, offset, num2, blockSize, (!encryptThenMac) ? size : 0);
bool flag = num4 == 0;
int num5 = num2 - num4;
if (!encryptThenMac)
{
num5 -= size;
int num6 = num5;
int num7 = offset + num6;
byte[] b2 = Arrays.CopyOfRange(ciphertext, num7, num7 + size);
byte[] a2 = mReadMac.CalculateMacConstantTime(seqNo, type, ciphertext, offset, num6, num2 - size, randomData);
flag |= !Arrays.ConstantTimeAreEqual(a2, b2);
}
if (flag)
{
throw new TlsFatalAlert(20);
}
return(Arrays.CopyOfRange(ciphertext, offset, offset + num5));
}
public byte[] DecodeCiphertext(short type, byte[] ciphertext, int offset, int len)
{
// TODO TLS 1.1 (RFC 4346) introduces an explicit IV
int minLength = readMac.Size + 1;
int blocksize = decryptCipher.GetBlockSize();
bool decrypterror = false;
/*
* ciphertext must be at least (macsize + 1) bytes long
*/
if (len < minLength)
{
handler.FailWithError(TlsProtocolHandler.AL_fatal, TlsProtocolHandler.AP_decode_error);
}
/*
* ciphertext must be a multiple of blocksize
*/
if (len % blocksize != 0)
{
handler.FailWithError(TlsProtocolHandler.AL_fatal, TlsProtocolHandler.AP_decryption_failed);
}
/*
* Decrypt all the ciphertext using the blockcipher
*/
for (int i = 0; i < len; i += blocksize)
{
decryptCipher.ProcessBlock(ciphertext, i + offset, ciphertext, i + offset);
}
/*
* Check if padding is correct
*/
int lastByteOffset = offset + len - 1;
byte paddingsizebyte = ciphertext[lastByteOffset];
int paddingsize = paddingsizebyte;
int maxPaddingSize = len - minLength;
if (paddingsize > maxPaddingSize)
{
decrypterror = true;
paddingsize = 0;
}
else
{
/*
* Now, check all the padding-bytes (constant-time comparison).
*/
byte diff = 0;
for (int i = lastByteOffset - paddingsize; i < lastByteOffset; ++i)
{
diff |= (byte)(ciphertext[i] ^ paddingsizebyte);
}
if (diff != 0)
{
/* Wrong padding */
decrypterror = true;
paddingsize = 0;
}
}
/*
* We now don't care if padding verification has failed or not, we will calculate
* the mac to give an attacker no kind of timing profile he can use to find out if
* mac verification failed or padding verification failed.
*/
int plaintextlength = len - minLength - paddingsize;
byte[] calculatedMac = readMac.CalculateMac(type, ciphertext, offset, plaintextlength);
/*
* Check all bytes in the mac (constant-time comparison).
*/
byte[] decryptedMac = new byte[calculatedMac.Length];
Array.Copy(ciphertext, offset + plaintextlength, decryptedMac, 0, calculatedMac.Length);
if (!Arrays.ConstantTimeAreEqual(calculatedMac, decryptedMac))
{
decrypterror = true;
}
/*
* Now, it is safe to fail.
*/
if (decrypterror)
{
handler.FailWithError(TlsProtocolHandler.AL_fatal, TlsProtocolHandler.AP_bad_record_mac);
}
byte[] plaintext = new byte[plaintextlength];
Array.Copy(ciphertext, offset, plaintext, 0, plaintextlength);
return(plaintext);
}
internal override byte[] DecodeCiphertext(
short type,
byte[] ciphertext,
int offset,
int len,
TlsProtocolHandler handler)
{
int blocksize = decryptCipher.GetBlockSize();
bool decrypterror = false;
/*
* Decrypt all the ciphertext using the blockcipher
*/
for (int i = 0; i < len; i += blocksize)
{
decryptCipher.ProcessBlock(ciphertext, i + offset, ciphertext, i
+ offset);
}
/*
* Check if padding is correct
*/
int paddingsize = ciphertext[offset + len - 1];
if (offset + len - 1 - paddingsize < 0)
{
/*
* This would lead to an negativ array index, so this padding
* must be incorrect!
*/
decrypterror = true;
paddingsize = 0;
}
else
{
/*
* Now, check all the padding-bytes.
*/
for (int i = 0; i <= paddingsize; i++)
{
if (ciphertext[offset + len - 1 - i] != paddingsize)
{
/* Wrong padding */
decrypterror = true;
}
}
}
/*
* We now don't care if padding verification has failed or not,
* we will calculate the mac to give an attacker no kind of timing
* profile he can use to find out if mac verification failed or
* padding verification failed.
*/
int plaintextlength = len - readMac.Size - paddingsize - 1;
byte[] calculatedMac = readMac.CalculateMac(type, ciphertext, offset,
plaintextlength);
/*
* Check all bytes in the mac.
*/
for (int i = 0; i < calculatedMac.Length; i++)
{
if (ciphertext[offset + plaintextlength + i] != calculatedMac[i])
{
decrypterror = true;
}
}
/*
* Now, it is save to fail.
*/
if (decrypterror)
{
handler.FailWithError(TlsProtocolHandler.AL_fatal,
TlsProtocolHandler.AP_bad_record_mac);
}
byte[] plaintext = new byte[plaintextlength];
Array.Copy(ciphertext, offset, plaintext, 0, plaintextlength);
return(plaintext);
}
/// <exception cref="IOException"></exception>
public virtual byte[] DecodeCiphertext(long seqNo, byte type, byte[] ciphertext, int offset, int len)
{
int blockSize = decryptCipher.GetBlockSize();
int macSize = mReadMac.Size;
int minLen = blockSize;
if (encryptThenMac)
{
minLen += macSize;
}
else
{
minLen = System.Math.Max(minLen, macSize + 1);
}
if (useExplicitIV)
{
minLen += blockSize;
}
if (len < minLen)
{
throw new TlsFatalAlert(AlertDescription.decode_error);
}
int blocks_length = len;
if (encryptThenMac)
{
blocks_length -= macSize;
}
if (blocks_length % blockSize != 0)
{
throw new TlsFatalAlert(AlertDescription.decryption_failed);
}
if (encryptThenMac)
{
int end = offset + len;
byte[] receivedMac = Arrays.CopyOfRange(ciphertext, end - macSize, end);
byte[] calculatedMac = mReadMac.CalculateMac(seqNo, type, ciphertext, offset, len - macSize);
bool badMacEtm = !Arrays.ConstantTimeAreEqual(calculatedMac, receivedMac);
if (badMacEtm)
{
/*
* RFC 7366 3. The MAC SHALL be evaluated before any further processing such as
* decryption is performed, and if the MAC verification fails, then processing SHALL
* terminate immediately. For TLS, a fatal bad_record_mac MUST be generated [2]. For
* DTLS, the record MUST be discarded, and a fatal bad_record_mac MAY be generated
* [4]. This immediate response to a bad MAC eliminates any timing channels that may
* be available through the use of manipulated packet data.
*/
throw new TlsFatalAlert(AlertDescription.bad_record_mac);
}
}
if (useExplicitIV)
{
decryptCipher.Init(false, new ParametersWithIV(null, ciphertext, offset, blockSize));
offset += blockSize;
blocks_length -= blockSize;
}
for (int i = 0; i < blocks_length; i += blockSize)
{
decryptCipher.ProcessBlock(ciphertext, offset + i, ciphertext, offset + i);
}
// If there's anything wrong with the padding, this will return zero
int totalPad = CheckPaddingConstantTime(ciphertext, offset, blocks_length, blockSize, encryptThenMac ? 0 : macSize);
bool badMac = (totalPad == 0);
int dec_output_length = blocks_length - totalPad;
if (!encryptThenMac)
{
dec_output_length -= macSize;
int macInputLen = dec_output_length;
int macOff = offset + macInputLen;
byte[] receivedMac = Arrays.CopyOfRange(ciphertext, macOff, macOff + macSize);
byte[] calculatedMac = mReadMac.CalculateMacConstantTime(seqNo, type, ciphertext, offset, macInputLen,
blocks_length - macSize, randomData);
badMac |= !Arrays.ConstantTimeAreEqual(calculatedMac, receivedMac);
}
if (badMac)
{
throw new TlsFatalAlert(AlertDescription.bad_record_mac);
}
return(Arrays.CopyOfRange(ciphertext, offset, offset + dec_output_length));
}
public virtual byte[] EncodePlaintext(long seqNo, byte type, byte[] plaintext, int offset, int len)
{
int blockSize = encryptCipher.GetBlockSize();
int macSize = mWriteMac.Size;
ProtocolVersion version = context.ServerVersion;
int enc_input_length = len;
if (!encryptThenMac)
{
enc_input_length += macSize;
}
int padding_length = blockSize - 1 - (enc_input_length % blockSize);
// TODO[DTLS] Consider supporting in DTLS (without exceeding send limit though)
if (!version.IsDtls && !version.IsSsl)
{
// Add a random number of extra blocks worth of padding
int maxExtraPadBlocks = (255 - padding_length) / blockSize;
int actualExtraPadBlocks = ChooseExtraPadBlocks(context.SecureRandom, maxExtraPadBlocks);
padding_length += actualExtraPadBlocks * blockSize;
}
int totalSize = len + macSize + padding_length + 1;
if (useExplicitIV)
{
totalSize += blockSize;
}
byte[] outBuf = new byte[totalSize];
int outOff = 0;
if (useExplicitIV)
{
byte[] explicitIV = new byte[blockSize];
context.NonceRandomGenerator.NextBytes(explicitIV);
encryptCipher.Init(true, new ParametersWithIV(null, explicitIV));
Array.Copy(explicitIV, 0, outBuf, outOff, blockSize);
outOff += blockSize;
}
int blocks_start = outOff;
Array.Copy(plaintext, offset, outBuf, outOff, len);
outOff += len;
if (!encryptThenMac)
{
byte[] mac = mWriteMac.CalculateMac(seqNo, type, plaintext, offset, len);
Array.Copy(mac, 0, outBuf, outOff, mac.Length);
outOff += mac.Length;
}
for (int i = 0; i <= padding_length; i++)
{
outBuf[outOff++] = (byte)padding_length;
}
for (int i = blocks_start; i < outOff; i += blockSize)
{
encryptCipher.ProcessBlock(outBuf, i, outBuf, i);
}
if (encryptThenMac)
{
byte[] mac = mWriteMac.CalculateMac(seqNo, type, outBuf, 0, outOff);
Array.Copy(mac, 0, outBuf, outOff, mac.Length);
outOff += mac.Length;
}
// assert outBuf.length == outOff;
return(outBuf);
}
/// <exception cref="IOException"></exception>
public virtual byte[] DecodeCiphertext(long seqNo, byte type, byte[] ciphertext, int offset, int len)
{
int blockSize = decryptCipher.GetBlockSize();
int macSize = mReadMac.Size;
int minLen = blockSize;
if (encryptThenMac)
{
minLen += macSize;
}
else
{
minLen = System.Math.Max(minLen, macSize + 1);
}
if (useExplicitIV)
{
minLen += blockSize;
}
if (len < minLen)
{
throw new TlsFatalAlert(AlertDescription.decode_error);
}
int blocks_length = len;
if (encryptThenMac)
{
blocks_length -= macSize;
}
if (blocks_length % blockSize != 0)
{
throw new TlsFatalAlert(AlertDescription.decryption_failed);
}
if (encryptThenMac)
{
int end = offset + len;
byte[] receivedMac = Arrays.CopyOfRange(ciphertext, end - macSize, end);
byte[] calculatedMac = mReadMac.CalculateMac(seqNo, type, ciphertext, offset, len - macSize);
bool badMac = !Arrays.ConstantTimeAreEqual(calculatedMac, receivedMac);
if (badMac)
{
throw new TlsFatalAlert(AlertDescription.bad_record_mac);
}
}
if (useExplicitIV)
{
decryptCipher.Init(false, new ParametersWithIV(null, ciphertext, offset, blockSize));
offset += blockSize;
blocks_length -= blockSize;
}
for (int i = 0; i < blocks_length; i += blockSize)
{
decryptCipher.ProcessBlock(ciphertext, offset + i, ciphertext, offset + i);
}
// If there's anything wrong with the padding, this will return zero
int totalPad = CheckPaddingConstantTime(ciphertext, offset, blocks_length, blockSize, encryptThenMac ? 0 : macSize);
int dec_output_length = blocks_length - totalPad;
if (!encryptThenMac)
{
dec_output_length -= macSize;
int macInputLen = dec_output_length;
int macOff = offset + macInputLen;
byte[] receivedMac = Arrays.CopyOfRange(ciphertext, macOff, macOff + macSize);
byte[] calculatedMac = mReadMac.CalculateMacConstantTime(seqNo, type, ciphertext, offset, macInputLen,
blocks_length - macSize, randomData);
bool badMac = !Arrays.ConstantTimeAreEqual(calculatedMac, receivedMac);
if (badMac || totalPad == 0)
{
throw new TlsFatalAlert(AlertDescription.bad_record_mac);
}
}
return(Arrays.CopyOfRange(ciphertext, offset, offset + dec_output_length));
}
public virtual byte[] EncodePlaintext(long seqNo, byte type, byte[] plaintext, int offset, int len)
{
int blockSize = encryptCipher.GetBlockSize();
int size = mWriteMac.Size;
ProtocolVersion serverVersion = context.ServerVersion;
int num = len;
if (!encryptThenMac)
{
num += size;
}
int num2 = blockSize - 1 - num % blockSize;
if (!serverVersion.IsDtls && !serverVersion.IsSsl)
{
int max = (255 - num2) / blockSize;
int num3 = ChooseExtraPadBlocks(context.SecureRandom, max);
num2 += num3 * blockSize;
}
int num4 = len + size + num2 + 1;
if (useExplicitIV)
{
num4 += blockSize;
}
byte[] array = new byte[num4];
int num5 = 0;
if (useExplicitIV)
{
byte[] array2 = new byte[blockSize];
context.NonceRandomGenerator.NextBytes(array2);
encryptCipher.Init(forEncryption: true, new ParametersWithIV(null, array2));
global::System.Array.Copy((global::System.Array)array2, 0, (global::System.Array)array, num5, blockSize);
num5 += blockSize;
}
int num6 = num5;
global::System.Array.Copy((global::System.Array)plaintext, offset, (global::System.Array)array, num5, len);
num5 += len;
if (!encryptThenMac)
{
byte[] array3 = mWriteMac.CalculateMac(seqNo, type, plaintext, offset, len);
global::System.Array.Copy((global::System.Array)array3, 0, (global::System.Array)array, num5, array3.Length);
num5 += array3.Length;
}
for (int i = 0; i <= num2; i++)
{
array[num5++] = (byte)num2;
}
for (int j = num6; j < num5; j += blockSize)
{
encryptCipher.ProcessBlock(array, j, array, j);
}
if (encryptThenMac)
{
byte[] array4 = mWriteMac.CalculateMac(seqNo, type, array, 0, num5);
global::System.Array.Copy((global::System.Array)array4, 0, (global::System.Array)array, num5, array4.Length);
num5 += array4.Length;
}
return(array);
}