/// <summary>
/// Detect file format of a SSH private key file.
/// </summary>
/// <returns>format type</returns>
/// <exception cref="IOException">File I/O error</exception>
public PrivateKeyFileFormat ProbeFormat()
{
if (keyFile == null)
{
return(PrivateKeyFileFormat.UNKNOWN);
}
if (ByteArrayUtil.ByteArrayStartsWith(keyFile, Encoding.ASCII.GetBytes(PrivateKeyFileHeader.SSH1_HEADER)))
{
return(PrivateKeyFileFormat.SSH1);
}
if (ByteArrayUtil.ByteArrayStartsWith(keyFile, Encoding.ASCII.GetBytes(PrivateKeyFileHeader.SSH2_OPENSSH_HEADER_RSA)) ||
ByteArrayUtil.ByteArrayStartsWith(keyFile, Encoding.ASCII.GetBytes(PrivateKeyFileHeader.SSH2_OPENSSH_HEADER_DSA)))
{
return(PrivateKeyFileFormat.SSH2_OPENSSH);
}
if (ByteArrayUtil.ByteArrayStartsWith(keyFile, Encoding.ASCII.GetBytes(PrivateKeyFileHeader.SSH2_SSHCOM_HEADER)))
{
return(PrivateKeyFileFormat.SSH2_SSHCOM);
}
if (ByteArrayUtil.ByteArrayStartsWith(keyFile, Encoding.ASCII.GetBytes(PrivateKeyFileHeader.SSH2_PUTTY_HEADER_1)) ||
ByteArrayUtil.ByteArrayStartsWith(keyFile, Encoding.ASCII.GetBytes(PrivateKeyFileHeader.SSH2_PUTTY_HEADER_2)))
{
return(PrivateKeyFileFormat.SSH2_PUTTY);
}
return(PrivateKeyFileFormat.UNKNOWN);
}
/// <summary>
/// Read PuTTY SSH2 private key parameters.
/// </summary>
/// <param name="passphrase">passphrase for decrypt the key file</param>
/// <param name="keyPair">key pair</param>
/// <param name="comment">comment or empty if it didn't exist</param>
public void Load(string passphrase, out KeyPair keyPair, out string comment)
{
if (keyFile == null)
{
throw new SSHException("A key file is not loaded yet");
}
int version;
string keyTypeName;
KeyType keyType;
string encryptionName;
CipherAlgorithm?encryption;
byte[] publicBlob;
byte[] privateBlob;
string privateMac;
string privateHash;
using (StreamReader sreader = GetStreamReader()) {
//*** Read header and key type
ReadHeaderLine(sreader, out version, out keyTypeName);
if (keyTypeName == "ssh-rsa")
{
keyType = KeyType.RSA;
}
else if (keyTypeName == "ssh-dss")
{
keyType = KeyType.DSA;
}
else
{
throw new SSHException(Strings.GetString("NotValidPrivateKeyFile") + " (unexpected key type)");
}
//*** Read encryption
ReadItemLine(sreader, "Encryption", out encryptionName);
if (encryptionName == "aes256-cbc")
{
encryption = CipherAlgorithm.AES256;
}
else if (encryptionName == "none")
{
encryption = null;
}
else
{
throw new SSHException(Strings.GetString("NotValidPrivateKeyFile") + " (unexpected encryption)");
}
//*** Read comment
ReadItemLine(sreader, "Comment", out comment);
//*** Read public lines
string publicLinesStr;
ReadItemLine(sreader, "Public-Lines", out publicLinesStr);
int publicLines;
if (!Int32.TryParse(publicLinesStr, out publicLines) || publicLines < 0)
{
throw new SSHException(Strings.GetString("NotValidPrivateKeyFile") + " (invalid public lines)");
}
ReadBlob(sreader, publicLines, out publicBlob);
//*** Read private lines
string privateLinesStr;
ReadItemLine(sreader, "Private-Lines", out privateLinesStr);
int privateLines;
if (!Int32.TryParse(privateLinesStr, out privateLines) || privateLines < 0)
{
throw new SSHException(Strings.GetString("NotValidPrivateKeyFile") + " (invalid private lines)");
}
ReadBlob(sreader, privateLines, out privateBlob);
//*** Read private MAC
ReadPrivateMACLine(sreader, version, out privateMac, out privateHash);
}
if (encryption.HasValue)
{
byte[] key = PuTTYPassphraseToKey(passphrase);
byte[] iv = new byte[16];
Cipher cipher = CipherFactory.CreateCipher(SSHProtocol.SSH2, encryption.Value, key, iv);
if (privateBlob.Length % cipher.BlockSize != 0)
{
throw new SSHException(Strings.GetString("NotValidPrivateKeyFile") + " (invalid key data size)");
}
cipher.Decrypt(privateBlob, 0, privateBlob.Length, privateBlob, 0);
}
bool verified = Verify(version, privateMac, privateHash,
passphrase, keyTypeName, encryptionName, comment, publicBlob, privateBlob);
if (!verified)
{
if (encryption.HasValue)
{
throw new SSHException(Strings.GetString("WrongPassphrase"));
}
else
{
throw new SSHException(Strings.GetString("NotValidPrivateKeyFile") + " (HMAC verification failed)");
}
}
if (keyType == KeyType.RSA)
{
SSH2DataReader reader = new SSH2DataReader(publicBlob);
byte[] magic = reader.ReadString();
if (!ByteArrayUtil.AreEqual(magic, Encoding.ASCII.GetBytes("ssh-rsa")))
{
throw new SSHException(Strings.GetString("NotValidPrivateKeyFile") + " (missing magic)");
}
BigInteger e = reader.ReadMPInt();
BigInteger n = reader.ReadMPInt();
reader = new SSH2DataReader(privateBlob);
BigInteger d = reader.ReadMPInt();
BigInteger p = reader.ReadMPInt();
BigInteger q = reader.ReadMPInt();
BigInteger iqmp = reader.ReadMPInt();
BigInteger u = p.modInverse(q);
keyPair = new RSAKeyPair(e, d, n, u, p, q);
}
else if (keyType == KeyType.DSA)
{
SSH2DataReader reader = new SSH2DataReader(publicBlob);
byte[] magic = reader.ReadString();
if (!ByteArrayUtil.AreEqual(magic, Encoding.ASCII.GetBytes("ssh-dss")))
{
throw new SSHException(Strings.GetString("NotValidPrivateKeyFile") + " (missing magic)");
}
BigInteger p = reader.ReadMPInt();
BigInteger q = reader.ReadMPInt();
BigInteger g = reader.ReadMPInt();
BigInteger y = reader.ReadMPInt();
reader = new SSH2DataReader(privateBlob);
BigInteger x = reader.ReadMPInt();
keyPair = new DSAKeyPair(p, g, q, y, x);
}
else
{
throw new SSHException("Unknown file type. This should not happen.");
}
}
