/**
* Test public key encryption.
*
* @throws Exception When test fails.
*/
@Test
public void testActivationGenerate() throws Exception {
String activationOTP = "CKZ2O-OE544";
String activationIdShort = "IFA6F-3NPAZ";
byte[] activationNonce = BaseEncoding.base64().decode("grDwkvXrgfUdKBsqg0xYYw==");
byte[] publicKeyBytes =
BaseEncoding.base64()
.decode(
"BJXfJMCANX+T9FzsG6Hi0KTYPN64i7HxMiWoMYPd17DYfBR+IwzOesTh/jj/B3trL9m3O1oODYil+8ssJzDt/QA=");
byte[] ephemeralPrivateKeyBytes =
BaseEncoding.base64().decode("AKeMTtivK/XRiQPhfJYxAw1L62ah4lGTQ4JKqRrr0fnC");
byte[] masterPublicKey =
BaseEncoding.base64()
.decode(
"BFOqvpLNi15eHDt8fkFxFe034Buw/i8gR3ax4fKiIQynt5K858oBBYhqLVH8FhNmMnlysnRd2UsPJSQxzoPhEn8=");
CryptoProviderUtil keyConvertor = PowerAuthConfiguration.INSTANCE.getKeyConvertor();
PrivateKey eph = keyConvertor.convertBytesToPrivateKey(ephemeralPrivateKeyBytes);
PublicKey mpk = keyConvertor.convertBytesToPublicKey(masterPublicKey);
PublicKey publicKey =
PowerAuthConfiguration.INSTANCE.getKeyConvertor().convertBytesToPublicKey(publicKeyBytes);
PowerAuthClientActivation activation = new PowerAuthClientActivation();
byte[] cDevicePublicKey =
activation.encryptDevicePublicKey(
publicKey, eph, mpk, activationOTP, activationIdShort, activationNonce);
assertArrayEquals(
cDevicePublicKey,
BaseEncoding.base64()
.decode(
"tnAyB0C5I9xblLlFCPONUT4GtABvutPkRvvx2oTeGIuUMAmUYTqJluKn/Zge+vbq+VArIVNYVTd+0yuBZGVtkkd1mTcc2eTDhqZSQJS6mMgmKeCqv64c6E4dm4INOkxh"));
}
/**
* Decrypt the device public key using activation OTP.
*
* @param C_devicePublicKey Encrypted device public key.
* @param activationIdShort Short activation ID.
* @param activationOTP Activation OTP value.
* @param activationNonce Activation nonce, used as an initialization vector for AES encryption.
* @return A decrypted public key.
*/
public PublicKey decryptDevicePublicKey(
byte[] C_devicePublicKey,
String activationIdShort,
String activationOTP,
byte[] activationNonce) {
try {
// Derive longer key from short activation ID and activation OTP
byte[] activationIdShortBytes = activationIdShort.getBytes("UTF-8");
SecretKey otpBasedSymmetricKey =
new KeyGenerator().deriveSecretKeyFromPassword(activationOTP, activationIdShortBytes);
// Decrypt device public key
AESEncryptionUtils aes = new AESEncryptionUtils();
byte[] decryptedPublicKeyBytes =
aes.decrypt(C_devicePublicKey, activationNonce, otpBasedSymmetricKey);
PublicKey devicePublicKey =
PowerAuthConfiguration.INSTANCE
.getKeyConvertor()
.convertBytesToPublicKey(decryptedPublicKeyBytes);
return devicePublicKey;
} catch (IllegalBlockSizeException
| InvalidKeySpecException
| BadPaddingException
| InvalidKeyException
| UnsupportedEncodingException ex) {
Logger.getLogger(PowerAuthServerActivation.class.getName()).log(Level.SEVERE, null, ex);
}
return null;
}
/**
* Test that the keys are correctly generated.
*
* @throws Exception When test fails.
*/
@Test
public void testGenerateKeys() throws Exception {
CryptoProviderUtil keyConvertor = PowerAuthConfiguration.INSTANCE.getKeyConvertor();
KeyGenerator keyGenerator = new KeyGenerator();
KeyPair kp = keyGenerator.generateKeyPair();
System.out.println(
"Private Key: "
+ BaseEncoding.base64().encode(keyConvertor.convertPrivateKeyToBytes(kp.getPrivate())));
System.out.println(
"Public Key: "
+ BaseEncoding.base64().encode(keyConvertor.convertPublicKeyToBytes(kp.getPublic())));
}
/**
* Compute a fingerprint of the device public key. The fingerprint can be used for visual
* validation of an exchanged public key.
*
* @param devicePublicKey Public key for computing fingerprint.
* @return Fingerprint of the public key.
*/
public int computeDevicePublicKeyFingerprint(PublicKey devicePublicKey) {
try {
byte[] devicePublicKeyBytes =
PowerAuthConfiguration.INSTANCE
.getKeyConvertor()
.convertPublicKeyToBytes(devicePublicKey);
MessageDigest digest = MessageDigest.getInstance("SHA-256");
byte[] hash = digest.digest(devicePublicKeyBytes);
if (hash.length < 4) { // assert
throw new IndexOutOfBoundsException();
}
int index = hash.length - 4;
int number =
(ByteBuffer.wrap(hash).getInt(index) & 0x7FFFFFFF)
% (int) (Math.pow(10, PowerAuthConfiguration.FINGERPRINT_LENGTH));
return number;
} catch (NoSuchAlgorithmException ex) {
Logger.getLogger(PowerAuthServerActivation.class.getName()).log(Level.SEVERE, null, ex);
}
return 0;
}
/**
* Encrypt the server public key using activation OTP and device public key. As a technical
* component for public key encryption, an ephemeral private key is used (in order to deduce
* ephemeral symmetric key using ECDH).
*
* @param serverPublicKey Server public key to be encrypted.
* @param devicePublicKey Device public key used for encryption.
* @param ephemeralPrivateKey Ephemeral private key.
* @param activationOTP Activation OTP value.
* @param activationIdShort Short activation ID.
* @param activationNonce Activation nonce, used as an initialization vector for AES encryption.
* @return Encrypted server public key.
* @throws InvalidKeyException In case some of the provided keys is invalid.
*/
public byte[] encryptServerPublicKey(
PublicKey serverPublicKey,
PublicKey devicePublicKey,
PrivateKey ephemeralPrivateKey,
String activationOTP,
String activationIdShort,
byte[] activationNonce)
throws InvalidKeyException {
try {
// Convert public key to bytes
byte[] serverPublicKeyBytes =
PowerAuthConfiguration.INSTANCE
.getKeyConvertor()
.convertPublicKeyToBytes(serverPublicKey);
// Generate symmetric keys
KeyGenerator keyGenerator = new KeyGenerator();
SecretKey ephemeralSymmetricKey =
keyGenerator.computeSharedKey(ephemeralPrivateKey, devicePublicKey);
byte[] activationIdShortBytes = activationIdShort.getBytes("UTF-8");
SecretKey otpBasedSymmetricKey =
keyGenerator.deriveSecretKeyFromPassword(activationOTP, activationIdShortBytes);
// Encrypt the data
AESEncryptionUtils aes = new AESEncryptionUtils();
byte[] encryptedTMP =
aes.encrypt(serverPublicKeyBytes, activationNonce, otpBasedSymmetricKey);
byte[] encryptServerPublicKey =
aes.encrypt(encryptedTMP, activationNonce, ephemeralSymmetricKey);
return encryptServerPublicKey;
} catch (IllegalBlockSizeException | BadPaddingException | UnsupportedEncodingException ex) {
Logger.getLogger(PowerAuthServerActivation.class.getName()).log(Level.SEVERE, null, ex);
}
return null;
}