private void testTampering(boolean aeadAvailable)
throws InvalidKeyException, InvalidAlgorithmParameterException, NoSuchAlgorithmException,
NoSuchProviderException, NoSuchPaddingException, IllegalBlockSizeException,
BadPaddingException {
Cipher eax = Cipher.getInstance("AES/EAX/NoPadding", "BC");
final SecretKeySpec key = new SecretKeySpec(new byte[eax.getBlockSize()], eax.getAlgorithm());
final IvParameterSpec iv = new IvParameterSpec(new byte[eax.getBlockSize()]);
eax.init(Cipher.ENCRYPT_MODE, key, iv);
byte[] ciphertext = eax.doFinal(new byte[100]);
ciphertext[0] = (byte) (ciphertext[0] + 1); // Tamper
try {
eax.init(Cipher.DECRYPT_MODE, key, iv);
eax.doFinal(ciphertext);
fail("Tampered ciphertext should be invalid");
} catch (BadPaddingException e) {
if (aeadAvailable) {
if (!e.getClass().getName().equals("javax.crypto.AEADBadTagException")) {
fail("Tampered AEAD ciphertext should fail with AEADBadTagException when available.");
}
}
}
}
void showCipher(Cipher c, String kind) {
System.out.println(kind + " cipher provider: " + cipher.getProvider());
System.out.println(kind + " cipher algorithm: " + cipher.getAlgorithm());
}
EncryptedFormInformation(
String formId,
String formVersion,
FormController.InstanceMetadata instanceMetadata,
PublicKey rsaPublicKey,
Base64Wrapper wrapper) {
this.formId = formId;
this.formVersion = formVersion;
this.instanceMetadata = instanceMetadata;
this.rsaPublicKey = rsaPublicKey;
this.wrapper = wrapper;
// generate the symmetric key from random bits...
SecureRandom r = new SecureRandom();
byte[] key = new byte[SYMMETRIC_KEY_LENGTH / 8];
r.nextBytes(key);
SecretKeySpec sk = new SecretKeySpec(key, SYMMETRIC_ALGORITHM);
symmetricKey = sk;
// construct the fixed portion of the iv -- the ivSeedArray
// this is the md5 hash of the instanceID and the symmetric key
try {
MessageDigest md = MessageDigest.getInstance("MD5");
md.update(instanceMetadata.instanceId.getBytes(UTF_8));
md.update(key);
byte[] messageDigest = md.digest();
ivSeedArray = new byte[IV_BYTE_LENGTH];
for (int i = 0; i < IV_BYTE_LENGTH; ++i) {
ivSeedArray[i] = messageDigest[(i % messageDigest.length)];
}
} catch (NoSuchAlgorithmException e) {
Log.e(t, e.toString());
e.printStackTrace();
throw new IllegalArgumentException(e.getMessage());
} catch (UnsupportedEncodingException e) {
Log.e(t, e.toString());
e.printStackTrace();
throw new IllegalArgumentException(e.getMessage());
}
// construct the base64-encoded RSA-encrypted symmetric key
try {
Cipher pkCipher;
pkCipher = Cipher.getInstance(ASYMMETRIC_ALGORITHM);
// write AES key
pkCipher.init(Cipher.ENCRYPT_MODE, rsaPublicKey);
byte[] pkEncryptedKey = pkCipher.doFinal(key);
String alg = pkCipher.getAlgorithm();
Log.i(t, "AlgorithmUsed: " + alg);
base64RsaEncryptedSymmetricKey = wrapper.encodeToString(pkEncryptedKey);
} catch (NoSuchAlgorithmException e) {
Log.e(t, "Unable to encrypt the symmetric key");
e.printStackTrace();
throw new IllegalArgumentException(e.getMessage());
} catch (NoSuchPaddingException e) {
Log.e(t, "Unable to encrypt the symmetric key");
e.printStackTrace();
throw new IllegalArgumentException(e.getMessage());
} catch (InvalidKeyException e) {
Log.e(t, "Unable to encrypt the symmetric key");
e.printStackTrace();
throw new IllegalArgumentException(e.getMessage());
} catch (IllegalBlockSizeException e) {
Log.e(t, "Unable to encrypt the symmetric key");
e.printStackTrace();
throw new IllegalArgumentException(e.getMessage());
} catch (BadPaddingException e) {
Log.e(t, "Unable to encrypt the symmetric key");
e.printStackTrace();
throw new IllegalArgumentException(e.getMessage());
}
// start building elementSignatureSource...
appendElementSignatureSource(formId);
if (formVersion != null) {
appendElementSignatureSource(formVersion.toString());
}
appendElementSignatureSource(base64RsaEncryptedSymmetricKey);
appendElementSignatureSource(instanceMetadata.instanceId);
}
