#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
using System;
using System.IO;
using Org.BouncyCastle.Crypto.Modes;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Crypto.Tls
{
public class TlsAeadCipher
: TlsCipher
{
// TODO[draft-zauner-tls-aes-ocb-04] Apply data volume limit described in section 8.4
public const int NONCE_RFC5288 = 1;
/*
* draft-zauner-tls-aes-ocb-04 specifies the nonce construction from draft-ietf-tls-chacha20-poly1305-04
*/
internal const int NONCE_DRAFT_CHACHA20_POLY1305 = 2;
protected readonly TlsContext context;
protected readonly int macSize;
// TODO SecurityParameters.record_iv_length
protected readonly int record_iv_length;
protected readonly IAeadBlockCipher encryptCipher;
protected readonly IAeadBlockCipher decryptCipher;
protected readonly byte[] encryptImplicitNonce, decryptImplicitNonce;
protected readonly int nonceMode;
/// <exception cref="IOException"></exception>
public TlsAeadCipher(TlsContext context, IAeadBlockCipher clientWriteCipher, IAeadBlockCipher serverWriteCipher,
int cipherKeySize, int macSize)
: this(context, clientWriteCipher, serverWriteCipher, cipherKeySize, macSize, NONCE_RFC5288)
{
}
/// <exception cref="IOException"></exception>
internal TlsAeadCipher(TlsContext context, IAeadBlockCipher clientWriteCipher, IAeadBlockCipher serverWriteCipher,
int cipherKeySize, int macSize, int nonceMode)
{
if (!TlsUtilities.IsTlsV12(context))
throw new TlsFatalAlert(AlertDescription.internal_error);
this.nonceMode = nonceMode;
// TODO SecurityParameters.fixed_iv_length
int fixed_iv_length;
switch (nonceMode)
{
case NONCE_RFC5288:
fixed_iv_length = 4;
this.record_iv_length = 8;
break;
case NONCE_DRAFT_CHACHA20_POLY1305:
fixed_iv_length = 12;
this.record_iv_length = 0;
break;
default:
throw new TlsFatalAlert(AlertDescription.internal_error);
}
this.context = context;
this.macSize = macSize;
int key_block_size = (2 * cipherKeySize) + (2 * fixed_iv_length);
byte[] key_block = TlsUtilities.CalculateKeyBlock(context, key_block_size);
int offset = 0;
KeyParameter client_write_key = new KeyParameter(key_block, offset, cipherKeySize);
offset += cipherKeySize;
KeyParameter server_write_key = new KeyParameter(key_block, offset, cipherKeySize);
offset += cipherKeySize;
byte[] client_write_IV = Arrays.CopyOfRange(key_block, offset, offset + fixed_iv_length);
offset += fixed_iv_length;
byte[] server_write_IV = Arrays.CopyOfRange(key_block, offset, offset + fixed_iv_length);
offset += fixed_iv_length;
if (offset != key_block_size)
throw new TlsFatalAlert(AlertDescription.internal_error);
KeyParameter encryptKey, decryptKey;
if (context.IsServer)
{
this.encryptCipher = serverWriteCipher;
this.decryptCipher = clientWriteCipher;
this.encryptImplicitNonce = server_write_IV;
this.decryptImplicitNonce = client_write_IV;
encryptKey = server_write_key;
decryptKey = client_write_key;
}
else
{
this.encryptCipher = clientWriteCipher;
this.decryptCipher = serverWriteCipher;
this.encryptImplicitNonce = client_write_IV;
this.decryptImplicitNonce = server_write_IV;
encryptKey = client_write_key;
decryptKey = server_write_key;
}
byte[] dummyNonce = new byte[fixed_iv_length + record_iv_length];
this.encryptCipher.Init(true, new AeadParameters(encryptKey, 8 * macSize, dummyNonce));
this.decryptCipher.Init(false, new AeadParameters(decryptKey, 8 * macSize, dummyNonce));
}
public virtual int GetPlaintextLimit(int ciphertextLimit)
{
// TODO We ought to be able to ask the decryptCipher (independently of it's current state!)
return ciphertextLimit - macSize - record_iv_length;
}
/// <exception cref="IOException"></exception>
public virtual byte[] EncodePlaintext(long seqNo, byte type, byte[] plaintext, int offset, int len)
{
byte[] nonce = new byte[encryptImplicitNonce.Length + record_iv_length];
switch (nonceMode)
{
case NONCE_RFC5288:
Array.Copy(encryptImplicitNonce, 0, nonce, 0, encryptImplicitNonce.Length);
// RFC 5288/6655: The nonce_explicit MAY be the 64-bit sequence number.
TlsUtilities.WriteUint64(seqNo, nonce, encryptImplicitNonce.Length);
break;
case NONCE_DRAFT_CHACHA20_POLY1305:
TlsUtilities.WriteUint64(seqNo, nonce, nonce.Length - 8);
for (int i = 0; i < encryptImplicitNonce.Length; ++i)
{
nonce[i] ^= encryptImplicitNonce[i];
}
break;
default:
throw new TlsFatalAlert(AlertDescription.internal_error);
}
int plaintextOffset = offset;
int plaintextLength = len;
int ciphertextLength = encryptCipher.GetOutputSize(plaintextLength);
byte[] output = new byte[record_iv_length + ciphertextLength];
if (record_iv_length != 0)
{
Array.Copy(nonce, nonce.Length - record_iv_length, output, 0, record_iv_length);
}
int outputPos = record_iv_length;
byte[] additionalData = GetAdditionalData(seqNo, type, plaintextLength);
AeadParameters parameters = new AeadParameters(null, 8 * macSize, nonce, additionalData);
try
{
encryptCipher.Init(true, parameters);
outputPos += encryptCipher.ProcessBytes(plaintext, plaintextOffset, plaintextLength, output, outputPos);
outputPos += encryptCipher.DoFinal(output, outputPos);
}
catch (Exception e)
{
throw new TlsFatalAlert(AlertDescription.internal_error, e);
}
if (outputPos != output.Length)
{
// NOTE: Existing AEAD cipher implementations all give exact output lengths
throw new TlsFatalAlert(AlertDescription.internal_error);
}
return output;
}
/// <exception cref="IOException"></exception>
public virtual byte[] DecodeCiphertext(long seqNo, byte type, byte[] ciphertext, int offset, int len)
{
if (GetPlaintextLimit(len) < 0)
throw new TlsFatalAlert(AlertDescription.decode_error);
byte[] nonce = new byte[decryptImplicitNonce.Length + record_iv_length];
switch (nonceMode)
{
case NONCE_RFC5288:
Array.Copy(decryptImplicitNonce, 0, nonce, 0, decryptImplicitNonce.Length);
Array.Copy(ciphertext, offset, nonce, nonce.Length - record_iv_length, record_iv_length);
break;
case NONCE_DRAFT_CHACHA20_POLY1305:
TlsUtilities.WriteUint64(seqNo, nonce, nonce.Length - 8);
for (int i = 0; i < decryptImplicitNonce.Length; ++i)
{
nonce[i] ^= decryptImplicitNonce[i];
}
break;
default:
throw new TlsFatalAlert(AlertDescription.internal_error);
}
int ciphertextOffset = offset + record_iv_length;
int ciphertextLength = len - record_iv_length;
int plaintextLength = decryptCipher.GetOutputSize(ciphertextLength);
byte[] output = new byte[plaintextLength];
int outputPos = 0;
byte[] additionalData = GetAdditionalData(seqNo, type, plaintextLength);
AeadParameters parameters = new AeadParameters(null, 8 * macSize, nonce, additionalData);
try
{
decryptCipher.Init(false, parameters);
outputPos += decryptCipher.ProcessBytes(ciphertext, ciphertextOffset, ciphertextLength, output, outputPos);
outputPos += decryptCipher.DoFinal(output, outputPos);
}
catch (Exception e)
{
throw new TlsFatalAlert(AlertDescription.bad_record_mac, e);
}
if (outputPos != output.Length)
{
// NOTE: Existing AEAD cipher implementations all give exact output lengths
throw new TlsFatalAlert(AlertDescription.internal_error);
}
return output;
}
/// <exception cref="IOException"></exception>
protected virtual byte[] GetAdditionalData(long seqNo, byte type, int len)
{
/*
* additional_data = seq_num + TLSCompressed.type + TLSCompressed.version +
* TLSCompressed.length
*/
byte[] additional_data = new byte[13];
TlsUtilities.WriteUint64(seqNo, additional_data, 0);
TlsUtilities.WriteUint8(type, additional_data, 8);
TlsUtilities.WriteVersion(context.ServerVersion, additional_data, 9);
TlsUtilities.WriteUint16(len, additional_data, 11);
return additional_data;
}
}
}
#endif