/**
* @param s
* @return
* @throws GeneralSecurityException
* @throws UnsupportedEncodingException
*/
public static String decrypt(final String s)
throws GeneralSecurityException, UnsupportedEncodingException {
String decrypted = null;
try {
if (s != null) {
final SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("PBEWithMD5AndDES");
final SecretKey secretKey =
secretKeyFactory.generateSecret(new PBEKeySpec(secret.toCharArray()));
final Cipher cipher = Cipher.getInstance("PBEWithMD5AndDES");
cipher.init(Cipher.DECRYPT_MODE, secretKey, new PBEParameterSpec(SALT, 20));
final byte[] stringBytes = s.getBytes("UTF-8");
final byte[] decodedBytes = Base64.decode(stringBytes, Base64.DEFAULT);
final byte[] decryptedBytes = cipher.doFinal(decodedBytes);
decrypted = new String(decryptedBytes, "UTF-8");
}
} catch (GeneralSecurityException x) {
throw x;
} catch (UnsupportedEncodingException x) {
throw x;
} catch (Exception x) {
DBG.m(x);
}
return decrypted;
}
/**
* Generates a PublicKey instance from a string containing the Base64-encoded public key.
*
* @param encodedPublicKey Base64-encoded public key
* @throws IllegalArgumentException if encodedPublicKey is invalid
*/
private PublicKey generatePublicKey(String encodedPublicKey) {
try {
byte[] decodedKey = Base64.decode(encodedPublicKey);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_FACTORY_ALGORITHM);
return keyFactory.generatePublic(new X509EncodedKeySpec(decodedKey));
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException(e);
} catch (InvalidKeySpecException e) {
Log.e(TAG, "Invalid key specification.");
throw new IllegalArgumentException(e);
} catch (Base64DecoderException e) {
Log.e(TAG, "Base64 decoding failed.");
throw new IllegalArgumentException(e);
}
}
/**
* Verifies that the signature from the server matches the computed signature on the data.
* Returns true if the data is correctly signed.
*
* @param signedData signed data from server
* @param signature server signature
* @return true if the data and signature match
*/
private boolean verify(String signedData, String signature) {
Signature sig;
try {
sig = Signature.getInstance(SIGNATURE_ALGORITHM);
sig.initVerify(key);
sig.update(signedData.getBytes());
if (!sig.verify(Base64.decode(signature))) {
Log.e(TAG, "Signature verification failed.");
return false;
}
return true;
} catch (NoSuchAlgorithmException e) {
Log.e(TAG, "NoSuchAlgorithmException.");
} catch (InvalidKeyException e) {
Log.e(TAG, "Invalid key specification.");
} catch (SignatureException e) {
Log.e(TAG, "Signature exception.");
} catch (Base64DecoderException e) {
Log.e(TAG, "Base64 decoding failed.");
}
return false;
}