/// <summary>
/// Decrypts encrypted private key file data.
/// </summary>
/// <param name="cipherInfo">The cipher info.</param>
/// <param name="cipherData">Encrypted data.</param>
/// <param name="passPhrase">Decryption pass phrase.</param>
/// <param name="binarySalt">Decryption binary salt.</param>
/// <returns>Decrypted byte array.</returns>
/// <exception cref="System.ArgumentNullException">cipherInfo</exception>
/// <exception cref="ArgumentNullException"><paramref name="cipherInfo" />, <paramref name="cipherData" />, <paramref name="passPhrase" /> or <paramref name="binarySalt" /> is null.</exception>
private static byte[] DecryptKey(CipherInfo cipherInfo, byte[] cipherData, string passPhrase, byte[] binarySalt)
{
if (cipherInfo == null)
{
throw new ArgumentNullException("cipherInfo");
}
if (cipherData == null)
{
throw new ArgumentNullException("cipherData");
}
if (binarySalt == null)
{
throw new ArgumentNullException("binarySalt");
}
List <byte> cipherKey = new List <byte>();
using (var md5 = new MD5Hash())
{
var passwordBytes = Encoding.UTF8.GetBytes(passPhrase);
// Use 8 bytes binary salkt
var initVector = passwordBytes.Concat(binarySalt.Take(8));
var hash = md5.ComputeHash(initVector.ToArray()).AsEnumerable();
cipherKey.AddRange(hash);
while (cipherKey.Count < cipherInfo.KeySize / 8)
{
hash = hash.Concat(initVector);
hash = md5.ComputeHash(hash.ToArray());
cipherKey.AddRange(hash);
}
}
var cipher = cipherInfo.Cipher(cipherKey.ToArray(), binarySalt);
return(cipher.Decrypt(cipherData));
}
private void Open(Stream privateKey, string passPhrase)
{
if (privateKey == null)
{
throw new ArgumentNullException("privateKey");
}
Match privateKeyMatch = null;
using (StreamReader sr = new StreamReader(privateKey))
{
var text = sr.ReadToEnd();
privateKeyMatch = _privateKeyRegex.Match(text);
}
if (!privateKeyMatch.Success)
{
throw new SshException("Invalid private key file.");
}
var keyName = privateKeyMatch.Result("${keyName}");
var cipherName = privateKeyMatch.Result("${cipherName}");
var salt = privateKeyMatch.Result("${salt}");
var data = privateKeyMatch.Result("${data}");
var binaryData = System.Convert.FromBase64String(data);
byte[] decryptedData = null;
if (!string.IsNullOrEmpty(cipherName) && !string.IsNullOrEmpty(salt))
{
if (string.IsNullOrEmpty(passPhrase))
{
throw new SshPassPhraseNullOrEmptyException("Private key is encrypted but passphrase is empty.");
}
byte[] binarySalt = new byte[salt.Length / 2];
for (int i = 0; i < binarySalt.Length; i++)
{
binarySalt[i] = Convert.ToByte(salt.Substring(i * 2, 2), 16);
}
CipherInfo cipher = null;
switch (cipherName)
{
case "DES-EDE3-CBC":
cipher = new CipherInfo(192, (key, iv) => { return(new TripleDesCipher(key, new CbcCipherMode(iv), new PKCS7Padding())); });
break;
case "DES-EDE3-CFB":
cipher = new CipherInfo(192, (key, iv) => { return(new TripleDesCipher(key, new CfbCipherMode(iv), new PKCS7Padding())); });
break;
case "DES-CBC":
cipher = new CipherInfo(64, (key, iv) => { return(new DesCipher(key, new CbcCipherMode(iv), new PKCS7Padding())); });
break;
case "AES-128-CBC":
cipher = new CipherInfo(128, (key, iv) => { return(new AesCipher(key, new CbcCipherMode(iv), new PKCS7Padding())); });
break;
case "AES-192-CBC":
cipher = new CipherInfo(192, (key, iv) => { return(new AesCipher(key, new CbcCipherMode(iv), new PKCS7Padding())); });
break;
case "AES-256-CBC":
cipher = new CipherInfo(256, (key, iv) => { return(new AesCipher(key, new CbcCipherMode(iv), new PKCS7Padding())); });
break;
default:
throw new SshException(string.Format(CultureInfo.CurrentCulture, "Private key cipher \"{0}\" is not supported.", cipherName));
}
decryptedData = DecryptKey(cipher, binaryData, passPhrase, binarySalt);
}
else
{
decryptedData = binaryData;
}
switch (keyName)
{
case "RSA":
this._key = new RsaKey(decryptedData.ToArray());
this.HostKey = new KeyHostAlgorithm("ssh-rsa", this._key);
break;
case "DSA":
this._key = new DsaKey(decryptedData.ToArray());
this.HostKey = new KeyHostAlgorithm("ssh-dss", this._key);
break;
case "SSH2 ENCRYPTED":
var reader = new SshDataReader(decryptedData);
var magicNumber = reader.ReadUInt32();
if (magicNumber != 0x3f6ff9eb)
{
throw new SshException("Invalid SSH2 private key.");
}
var totalLength = reader.ReadUInt32(); // Read total bytes length including magic number
var keyType = reader.ReadString();
var ssh2CipherName = reader.ReadString();
var blobSize = (int)reader.ReadUInt32();
byte[] keyData = null;
if (ssh2CipherName == "none")
{
keyData = reader.ReadBytes(blobSize);
}
//else if (ssh2CipherName == "3des-cbc")
//{
// var key = GetCipherKey(passPhrase, 192 / 8);
// var ssh2Сipher = new TripleDesCipher(key, null, null);
// keyData = ssh2Сipher.Decrypt(reader.ReadBytes(blobSize));
//}
else
{
throw new SshException(string.Format("Cipher method '{0}' is not supported.", cipherName));
}
// TODO: Create two specific data types to avoid using SshDataReader class
reader = new SshDataReader(keyData);
var decryptedLength = reader.ReadUInt32();
if (decryptedLength + 4 != blobSize)
{
throw new SshException("Invalid passphrase.");
}
if (keyType == "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}")
{
var exponent = reader.ReadBigIntWithBits(); //e
var d = reader.ReadBigIntWithBits(); //d
var modulus = reader.ReadBigIntWithBits(); //n
var inverseQ = reader.ReadBigIntWithBits(); //u
var q = reader.ReadBigIntWithBits(); //p
var p = reader.ReadBigIntWithBits(); //q
this._key = new RsaKey(modulus, exponent, d, p, q, inverseQ);
this.HostKey = new KeyHostAlgorithm("ssh-rsa", this._key);
}
else if (keyType == "dl-modp{sign{dsa-nist-sha1},dh{plain}}")
{
var zero = reader.ReadUInt32();
if (zero != 0)
{
throw new SshException("Invalid private key");
}
var p = reader.ReadBigIntWithBits();
var g = reader.ReadBigIntWithBits();
var q = reader.ReadBigIntWithBits();
var y = reader.ReadBigIntWithBits();
var x = reader.ReadBigIntWithBits();
this._key = new DsaKey(p, q, g, y, x);
this.HostKey = new KeyHostAlgorithm("ssh-dss", this._key);
}
else
{
throw new NotSupportedException(string.Format("Key type '{0}' is not supported.", keyType));
}
break;
default:
throw new NotSupportedException(string.Format(CultureInfo.CurrentCulture, "Key '{0}' is not supported.", keyName));
}
}