private static byte[] EncryptKeyData(
byte[] rawKeyData,
SymmetricKeyAlgorithmTag encAlgorithm,
char[] passPhrase,
SecureRandom random,
out S2k s2k,
out byte[] iv)
{
IBufferedCipher c;
try
{
string cName = PgpUtilities.GetSymmetricCipherName(encAlgorithm);
c = CipherUtilities.GetCipher(cName + "/CFB/NoPadding");
}
catch (Exception e)
{
throw new PgpException("Exception creating cipher", e);
}
byte[] s2kIV = new byte[8];
random.NextBytes(s2kIV);
s2k = new S2k(HashAlgorithmTag.Sha1, s2kIV, 0x60);
KeyParameter kp = PgpUtilities.MakeKeyFromPassPhrase(encAlgorithm, s2k, passPhrase);
iv = new byte[c.GetBlockSize()];
random.NextBytes(iv);
c.Init(true, new ParametersWithRandom(new ParametersWithIV(kp, iv), random));
return(c.DoFinal(rawKeyData));
}
private IBufferedCipher CreateStreamCipher(
SymmetricKeyAlgorithmTag keyAlgorithm)
{
string mode = (encData is SymmetricEncIntegrityPacket)
? "CFB"
: "OpenPGPCFB";
string cName = PgpUtilities.GetSymmetricCipherName(keyAlgorithm)
+ "/" + mode + "/NoPadding";
return(CipherUtilities.GetCipher(cName));
}
public override void AddSessionInfo(
byte[] si,
SecureRandom random)
{
string cName = PgpUtilities.GetSymmetricCipherName(encAlgorithm);
IBufferedCipher c = CipherUtilities.GetCipher(cName + "/CFB/NoPadding");
byte[] iv = new byte[c.GetBlockSize()];
c.Init(true, new ParametersWithRandom(new ParametersWithIV(key, iv), random));
this.sessionInfo = c.DoFinal(si, 0, si.Length - 2);
}
/// <summary>Return the decrypted input stream, using the passed in passphrase.</summary>
public Stream GetDataStream(
char[] passPhrase)
{
try
{
SymmetricKeyAlgorithmTag keyAlgorithm = keyData.EncAlgorithm;
KeyParameter key = PgpUtilities.MakeKeyFromPassPhrase(
keyAlgorithm, keyData.S2k, passPhrase);
byte[] secKeyData = keyData.GetSecKeyData();
if (secKeyData != null && secKeyData.Length > 0)
{
IBufferedCipher keyCipher = CipherUtilities.GetCipher(
PgpUtilities.GetSymmetricCipherName(keyAlgorithm) + "/CFB/NoPadding");
keyCipher.Init(false,
new ParametersWithIV(key, new byte[keyCipher.GetBlockSize()]));
byte[] keyBytes = keyCipher.DoFinal(secKeyData);
keyAlgorithm = (SymmetricKeyAlgorithmTag)keyBytes[0];
key = ParameterUtilities.CreateKeyParameter(
PgpUtilities.GetSymmetricCipherName(keyAlgorithm),
keyBytes, 1, keyBytes.Length - 1);
}
IBufferedCipher c = CreateStreamCipher(keyAlgorithm);
byte[] iv = new byte[c.GetBlockSize()];
c.Init(false, new ParametersWithIV(key, iv));
encStream = BcpgInputStream.Wrap(new CipherStream(encData.GetInputStream(), c, null));
if (encData is SymmetricEncIntegrityPacket)
{
truncStream = new TruncatedStream(encStream);
string digestName = PgpUtilities.GetDigestName(HashAlgorithmTag.Sha1);
IDigest digest = DigestUtilities.GetDigest(digestName);
encStream = new DigestStream(truncStream, digest, null);
}
if (Streams.ReadFully(encStream, iv, 0, iv.Length) < iv.Length)
{
throw new EndOfStreamException("unexpected end of stream.");
}
int v1 = encStream.ReadByte();
int v2 = encStream.ReadByte();
if (v1 < 0 || v2 < 0)
{
throw new EndOfStreamException("unexpected end of stream.");
}
// Note: the oracle attack on the "quick check" bytes is not deemed
// a security risk for PBE (see PgpPublicKeyEncryptedData)
bool repeatCheckPassed =
iv[iv.Length - 2] == (byte)v1 &&
iv[iv.Length - 1] == (byte)v2;
// Note: some versions of PGP appear to produce 0 for the extra
// bytes rather than repeating the two previous bytes
bool zeroesCheckPassed =
v1 == 0 &&
v2 == 0;
if (!repeatCheckPassed && !zeroesCheckPassed)
{
throw new PgpDataValidationException("quick check failed.");
}
return(encStream);
}
catch (PgpException e)
{
throw e;
}
catch (Exception e)
{
throw new PgpException("Exception creating cipher", e);
}
}
private byte[] ExtractKeyData(
char[] passPhrase)
{
SymmetricKeyAlgorithmTag alg = secret.EncAlgorithm;
byte[] encData = secret.GetSecretKeyData();
if (alg == SymmetricKeyAlgorithmTag.Null)
{
return(encData);
}
byte[] data;
IBufferedCipher c = null;
try
{
string cName = PgpUtilities.GetSymmetricCipherName(alg);
c = CipherUtilities.GetCipher(cName + "/CFB/NoPadding");
}
catch (Exception e)
{
throw new PgpException("Exception creating cipher", e);
}
// TODO Factor this block out as 'encryptData'
try
{
KeyParameter key = PgpUtilities.MakeKeyFromPassPhrase(secret.EncAlgorithm, secret.S2k, passPhrase);
byte[] iv = secret.GetIV();
if (secret.PublicKeyPacket.Version == 4)
{
c.Init(false, new ParametersWithIV(key, iv));
data = c.DoFinal(encData);
bool useSha1 = secret.S2kUsage == SecretKeyPacket.UsageSha1;
byte[] check = Checksum(useSha1, data, (useSha1) ? data.Length - 20 : data.Length - 2);
for (int i = 0; i != check.Length; i++)
{
if (check[i] != data[data.Length - check.Length + i])
{
throw new PgpException("Checksum mismatch at " + i + " of " + check.Length);
}
}
}
else // version 2 or 3, RSA only.
{
data = new byte[encData.Length];
//
// read in the four numbers
//
int pos = 0;
for (int i = 0; i != 4; i++)
{
c.Init(false, new ParametersWithIV(key, iv));
int encLen = (((encData[pos] << 8) | (encData[pos + 1] & 0xff)) + 7) / 8;
data[pos] = encData[pos];
data[pos + 1] = encData[pos + 1];
pos += 2;
c.DoFinal(encData, pos, encLen, data, pos);
pos += encLen;
if (i != 3)
{
Array.Copy(encData, pos - iv.Length, iv, 0, iv.Length);
}
}
//
// verify Checksum
//
int cs = ((encData[pos] << 8) & 0xff00) | (encData[pos + 1] & 0xff);
int calcCs = 0;
for (int j = 0; j < data.Length - 2; j++)
{
calcCs += data[j] & 0xff;
}
calcCs &= 0xffff;
if (calcCs != cs)
{
throw new PgpException("Checksum mismatch: passphrase wrong, expected "
+ cs.ToString("X")
+ " found " + calcCs.ToString("X"));
}
}
return(data);
}
catch (PgpException e)
{
throw e;
}
catch (Exception e)
{
throw new PgpException("Exception decrypting key", e);
}
}
/// <summary>
/// <p>
/// If buffer is non null stream assumed to be partial, otherwise the length will be used
/// to output a fixed length packet.
/// </p>
/// <p>
/// The stream created can be closed off by either calling Close()
/// on the stream or Close() on the generator. Closing the returned
/// stream does not close off the Stream parameter <c>outStr</c>.
/// </p>
/// </summary>
private Stream Open(
Stream outStr,
long length,
byte[] buffer)
{
if (cOut != null)
{
throw new InvalidOperationException("generator already in open state");
}
if (methods.Count == 0)
{
throw new InvalidOperationException("No encryption methods specified");
}
if (outStr == null)
{
throw new ArgumentNullException("outStr");
}
pOut = new BcpgOutputStream(outStr);
KeyParameter key;
if (methods.Count == 1)
{
if (methods[0] is PbeMethod)
{
PbeMethod m = (PbeMethod)methods[0];
key = m.GetKey();
}
else
{
key = PgpUtilities.MakeRandomKey(defAlgorithm, rand);
byte[] sessionInfo = CreateSessionInfo(defAlgorithm, key);
PubMethod m = (PubMethod)methods[0];
try
{
m.AddSessionInfo(sessionInfo, rand);
}
catch (Exception e)
{
throw new PgpException("exception encrypting session key", e);
}
}
pOut.WritePacket((ContainedPacket)methods[0]);
}
else // multiple methods
{
key = PgpUtilities.MakeRandomKey(defAlgorithm, rand);
byte[] sessionInfo = CreateSessionInfo(defAlgorithm, key);
for (int i = 0; i != methods.Count; i++)
{
EncMethod m = (EncMethod)methods[i];
try
{
m.AddSessionInfo(sessionInfo, rand);
}
catch (Exception e)
{
throw new PgpException("exception encrypting session key", e);
}
pOut.WritePacket(m);
}
}
string cName = PgpUtilities.GetSymmetricCipherName(defAlgorithm);
if (cName == null)
{
throw new PgpException("null cipher specified");
}
try
{
if (withIntegrityPacket)
{
cName += "/CFB/NoPadding";
}
else
{
cName += "/OpenPGPCFB/NoPadding";
}
c = CipherUtilities.GetCipher(cName);
// TODO Confirm the IV should be all zero bytes (not inLineIv - see below)
byte[] iv = new byte[c.GetBlockSize()];
c.Init(true, new ParametersWithRandom(new ParametersWithIV(key, iv), rand));
if (buffer == null)
{
//
// we have to Add block size + 2 for the Generated IV and + 1 + 22 if integrity protected
//
if (withIntegrityPacket)
{
pOut = new BcpgOutputStream(outStr, PacketTag.SymmetricEncryptedIntegrityProtected, length + c.GetBlockSize() + 2 + 1 + 22);
pOut.WriteByte(1); // version number
}
else
{
pOut = new BcpgOutputStream(outStr, PacketTag.SymmetricKeyEncrypted, length + c.GetBlockSize() + 2, oldFormat);
}
}
else
{
if (withIntegrityPacket)
{
pOut = new BcpgOutputStream(outStr, PacketTag.SymmetricEncryptedIntegrityProtected, buffer);
pOut.WriteByte(1); // version number
}
else
{
pOut = new BcpgOutputStream(outStr, PacketTag.SymmetricKeyEncrypted, buffer);
}
}
int blockSize = c.GetBlockSize();
byte[] inLineIv = new byte[blockSize + 2];
rand.NextBytes(inLineIv, 0, blockSize);
Array.Copy(inLineIv, inLineIv.Length - 4, inLineIv, inLineIv.Length - 2, 2);
Stream myOut = cOut = new CipherStream(pOut, null, c);
if (withIntegrityPacket)
{
string digestName = PgpUtilities.GetDigestName(HashAlgorithmTag.Sha1);
IDigest digest = DigestUtilities.GetDigest(digestName);
myOut = digestOut = new DigestStream(myOut, null, digest);
}
myOut.Write(inLineIv, 0, inLineIv.Length);
return(new WrappedGeneratorStream(this, myOut));
}
catch (Exception e)
{
throw new PgpException("Exception creating cipher", e);
}
}
/// <summary>Return the decrypted data stream for the packet.</summary>
public Stream GetDataStream(
PgpPrivateKey privKey)
{
byte[] plain = fetchSymmetricKeyData(privKey);
IBufferedCipher c2;
string cipherName = PgpUtilities.GetSymmetricCipherName((SymmetricKeyAlgorithmTag)plain[0]);
string cName = cipherName;
try
{
if (encData is SymmetricEncIntegrityPacket)
{
cName += "/CFB/NoPadding";
}
else
{
cName += "/OpenPGPCFB/NoPadding";
}
c2 = CipherUtilities.GetCipher(cName);
}
catch (PgpException e)
{
throw e;
}
catch (Exception e)
{
throw new PgpException("exception creating cipher", e);
}
if (c2 == null)
{
return(encData.GetInputStream());
}
try
{
KeyParameter key = ParameterUtilities.CreateKeyParameter(
cipherName, plain, 1, plain.Length - 3);
byte[] iv = new byte[c2.GetBlockSize()];
c2.Init(false, new ParametersWithIV(key, iv));
encStream = BcpgInputStream.Wrap(new CipherStream(encData.GetInputStream(), c2, null));
if (encData is SymmetricEncIntegrityPacket)
{
truncStream = new TruncatedStream(encStream);
string digestName = PgpUtilities.GetDigestName(HashAlgorithmTag.Sha1);
IDigest digest = DigestUtilities.GetDigest(digestName);
encStream = new DigestStream(truncStream, digest, null);
}
if (Streams.ReadFully(encStream, iv, 0, iv.Length) < iv.Length)
{
throw new EndOfStreamException("unexpected end of stream.");
}
int v1 = encStream.ReadByte();
int v2 = encStream.ReadByte();
if (v1 < 0 || v2 < 0)
{
throw new EndOfStreamException("unexpected end of stream.");
}
// Note: the oracle attack on the "quick check" bytes is deemed
// a security risk for typical public key encryption usages,
// therefore we do not perform the check.
// bool repeatCheckPassed =
// iv[iv.Length - 2] == (byte)v1
// && iv[iv.Length - 1] == (byte)v2;
//
// // Note: some versions of PGP appear to produce 0 for the extra
// // bytes rather than repeating the two previous bytes
// bool zeroesCheckPassed =
// v1 == 0
// && v2 == 0;
//
// if (!repeatCheckPassed && !zeroesCheckPassed)
// {
// throw new PgpDataValidationException("quick check failed.");
// }
return(encStream);
}
catch (PgpException e)
{
throw e;
}
catch (Exception e)
{
throw new PgpException("Exception starting decryption", e);
}
}
