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));
}
/// <summary>Add a PBE encryption method to the encrypted object.</summary>
public void AddMethod(
char[] passPhrase,
HashAlgorithmTag s2kDigest)
{
byte[] iv = new byte[8];
rand.NextBytes(iv);
S2k s2k = new S2k(s2kDigest, iv, 0x60);
methods.Add(new PbeMethod(defAlgorithm, s2k, PgpUtilities.MakeKeyFromPassPhrase(defAlgorithm, s2k, passPhrase)));
}
/// <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);
}
}
