protected internal static Cipher InitCipherForBlock(Cipher cipher, int block,
IEncryptionInfoBuilder builder, ISecretKey skey, int encryptMode)
{
EncryptionVerifier ver = builder.GetVerifier();
HashAlgorithm hashAlgo = ver.HashAlgorithm;
byte[] blockKey = new byte[4];
LittleEndian.PutUInt(blockKey, 0, block);
MessageDigest hashAlg = CryptoFunctions.GetMessageDigest(hashAlgo);
hashAlg.Update(skey.GetEncoded());
byte[] encKey = hashAlg.Digest(blockKey);
EncryptionHeader header = builder.GetHeader();
int keyBits = header.KeySize;
encKey = CryptoFunctions.GetBlock0(encKey, keyBits / 8);
if (keyBits == 40)
{
encKey = CryptoFunctions.GetBlock0(encKey, 16);
}
ISecretKey key = new SecretKeySpec(encKey, skey.GetAlgorithm());
if (cipher == null)
{
cipher = CryptoFunctions.GetCipher(key, header.CipherAlgorithm, null, null, encryptMode);
}
else
{
cipher.Init(encryptMode, key);
}
return(cipher);
}
private async Task <byte[]> GetEncryptionKeyLockedAsync(string keyName)
{
byte[] key = null;
try
{
char[] deviceId = GetDeviceId().ToCharArray();
KeyStore keyStore = await GetOrCreateKeyStoreAsync(deviceId).ConfigureAwait(false);
KeyStore.IProtectionParameter protectionParameter = new KeyStore.PasswordProtection(deviceId);
KeyStore.SecretKeyEntry secretKeyEntry = (KeyStore.SecretKeyEntry)keyStore.GetEntry(keyName, protectionParameter);
if (secretKeyEntry != null)
{
ISecretKey secretKey = secretKeyEntry.SecretKey;
if (secretKey != null)
{
key = secretKey.GetEncoded();
}
}
}
catch (FileNotFoundException)
{
// If the file isn't found, it's not a big deal and should mean it's just the first run.
// The caller or the GetOrCreate method above will need to create it if we don't find it here.
}
return(key);
}
protected internal static Cipher InitCipherForBlock(Cipher existing, int block, bool lastChunk,
IEncryptionInfoBuilder builder, ISecretKey skey, int encryptionMode)
{
EncryptionHeader header = builder.GetHeader();
if (existing == null || lastChunk)
{
String pAdding = (lastChunk ? "PKCS5PAdding" : "NoPAdding");
existing = CryptoFunctions.GetCipher(skey, header.CipherAlgorithm, header.ChainingMode, header.KeySalt, encryptionMode, pAdding);
}
byte[] blockKey = new byte[4];
LittleEndian.PutInt(blockKey, 0, block);
byte[] iv = CryptoFunctions.GenerateIv(header.HashAlgorithm, header.KeySalt, blockKey, header.BlockSize);
AlgorithmParameterSpec aps;
if (header.CipherAlgorithm == CipherAlgorithm.rc2)
{
aps = new RC2ParameterSpec(skey.GetEncoded().Length * 8, iv);
}
else
{
aps = new IvParameterSpec(iv);
}
existing.Init(encryptionMode, skey, aps);
return(existing);
}
private async Task <byte[]> CreateAndStoreEncryptionKeyLockedAsync(string keyName)
{
byte[] keyBytes = null;
KeyGenerator keyGenerator = KeyGenerator.GetInstance("AES");
keyGenerator.Init(256, new SecureRandom());
ISecretKey key = keyGenerator.GenerateKey();
await StoreKeyAsync(keyName, key).ConfigureAwait(false);
keyBytes = key.GetEncoded();
return(keyBytes);
}
public AESObfuscator(byte[] salt, string password)
{
try {
SecretKeyFactory factory = SecretKeyFactory.GetInstance(KEYGEN_ALGORITHM);
PBEKeySpec keySpec =
new PBEKeySpec(password.ToCharArray(), salt, 1024, 256);
ISecretKey tmp = factory.GenerateSecret(keySpec);
ISecretKey secret = new SecretKeySpec(tmp.GetEncoded(), "AES");
mEncryptor = Cipher.GetInstance(CIPHER_ALGORITHM);
mEncryptor.Init(Cipher.EncryptMode, secret, new IvParameterSpec(IV));
mDecryptor = Cipher.GetInstance(CIPHER_ALGORITHM);
mDecryptor.Init(Cipher.DecryptMode, secret, new IvParameterSpec(IV));
} catch (GeneralSecurityException e) {
// This can't happen on a compatible Android device.
throw new RuntimeException("Invalid environment", e);
}
}
/// <summary>
/// Initializes a new instance of the <see cref="AesObfuscator"/> class.
/// The aes obfuscator.
/// </summary>
/// <param name="salt">
/// an array of random bytes to use for each (un)obfuscation
/// </param>
/// <param name="applicationId">
/// application identifier, e.g. the package name
/// </param>
/// <param name="deviceId">
/// device identifier. Use as many sources as possible to
/// create this unique identifier.
/// </param>
public AesObfuscator(byte[] salt, string applicationId, string deviceId)
{
try
{
SecretKeyFactory factory = SecretKeyFactory.GetInstance(KeygenAlgorithm);
IKeySpec keySpec = new PBEKeySpec((applicationId + deviceId).ToCharArray(), salt, 1024, 256);
ISecretKey tmp = factory.GenerateSecret(keySpec);
ISecretKey secret = new SecretKeySpec(tmp.GetEncoded(), "AES");
this.encryptor = Cipher.GetInstance(CipherAlgorithm);
this.encryptor.Init(CipherMode.EncryptMode, secret, new IvParameterSpec(Iv));
this.decryptor = Cipher.GetInstance(CipherAlgorithm);
this.decryptor.Init(CipherMode.DecryptMode, secret, new IvParameterSpec(Iv));
}
catch (GeneralSecurityException e)
{
// This can't happen on a compatible Android device.
throw new RuntimeException("Invalid environment", e);
}
}
protected internal static Cipher InitCipherForBlock(Cipher cipher, int block,
IEncryptionInfoBuilder builder, ISecretKey skey, int encryptMode)
{
EncryptionVerifier ver = builder.GetVerifier();
HashAlgorithm hashAlgo = ver.HashAlgorithm;
byte[] blockKey = new byte[4];
LittleEndian.PutUInt(blockKey, 0, block);
byte[] encKey = CryptoFunctions.GenerateKey(skey.GetEncoded(), hashAlgo, blockKey, 16);
ISecretKey key = new SecretKeySpec(encKey, skey.GetAlgorithm());
if (cipher == null)
{
EncryptionHeader em = builder.GetHeader();
cipher = CryptoFunctions.GetCipher(key, em.CipherAlgorithm, null, null, encryptMode);
}
else
{
cipher.Init(encryptMode, key);
}
return(cipher);
}
private static byte[] Mac_3des(ISecretKey key, byte[] text, int offset, int length, byte[] iv)
{
if (length == -1)
{
length = text.Length - offset;
}
try
{
//Cipher cipher = Cipher.getInstance(DES3_CBC_CIPHER);
//cipher.init(Cipher.ENCRYPT_MODE, key, new IvParameterSpec(iv));
//byte[] res = cipher.doFinal(text, offset, length);
byte[] res = GPCrypto.DoEncrypt_DES3_CBC(key.GetEncoded(), text, offset, length, iv);
byte[] result = new byte[8];
Array.Copy(res, res.Length - 8, result, 0, 8);
return(result);
}
catch (Exception e)
{
throw new Exception("MAC computation failed.", e);
}
}