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);
}
}
/// <summary>
/// Requests that the specified Purchasable be purchased on behalf of the current user.
/// The IAP client service is responsible for identifying the user and requesting credentials as appropriate,
/// as well as providing all of the UI for the purchase flow. When purchases are successful, a Product object
/// is returned that describes the product that was purchased.
/// </summary>
/// <param name="product">The Purchasable object that describes the item to be purchased.</param>
/// <returns>Returns true if the purchase was successful.</returns>
public async Task<bool> RequestPurchaseAsync(Product product)
{
if (ReferenceEquals(product, null))
throw new ArgumentNullException("product");
var tcs = new TaskCompletionSource<bool>();
// Create the Purchasable object from the supplied product
var sr = SecureRandom.GetInstance("SHA1PRNG");
// This is an ID that allows you to associate a successful purchase with
// it's original request. The server does nothing with this string except
// pass it back to you, so it only needs to be unique within this instance
// of your app to allow you to pair responses with requests.
var uniqueId = sr.NextLong().ToString("X");
JSONObject purchaseRequest = new JSONObject();
purchaseRequest.Put("uuid", uniqueId);
purchaseRequest.Put("identifier", product.Identifier);
var purchaseRequestJson = purchaseRequest.ToString();
byte[] keyBytes = new byte[16];
sr.NextBytes(keyBytes);
var key = new SecretKeySpec(keyBytes, "AES");
byte[] ivBytes = new byte[16];
sr.NextBytes(ivBytes);
var iv = new IvParameterSpec(ivBytes);
Cipher cipher = Cipher.GetInstance("AES/CBC/PKCS5Padding", "BC");
cipher.Init(CipherMode.EncryptMode, key, iv);
var payload = cipher.DoFinal(Encoding.UTF8.GetBytes(purchaseRequestJson));
cipher = Cipher.GetInstance("RSA/ECB/PKCS1Padding", "BC");
cipher.Init(CipherMode.EncryptMode, _publicKey);
var encryptedKey = cipher.DoFinal(keyBytes);
var purchasable = new Purchasable(
product.Identifier,
Convert.ToBase64String(encryptedKey, Base64FormattingOptions.None),
Convert.ToBase64String(ivBytes, Base64FormattingOptions.None),
Convert.ToBase64String(payload, Base64FormattingOptions.None));
var listener = new PurchaseListener(tcs, _publicKey, product, uniqueId);
RequestPurchase(purchasable, listener);
// No timeout for purchase as it shows a user dialog
return await tcs.Task;
}
/// <summary>
/// Returns the secret key to use for initializing the Mac.
/// </summary>
/// <param name="algorithm">The algorithm.</param>
/// <param name="keyMaterial">The key material.</param>
/// <returns>The secret key.</returns>
internal static SecretKeySpec GetSecretKey(MacAlgorithm algorithm, byte[] keyMaterial)
{
string algorithmName = MacAlgorithmProviderFactory.GetAlgorithmName(algorithm);
var signingKey = new SecretKeySpec(keyMaterial, algorithmName);
return signingKey;
}
