I am very rarely use Java and I have an requirement of converting a function in Node.js which builds the HMAC signature for REST POST call to Java
Node JS function :
function buildSignature(buf, secret) {
const hmac = crypto.createHmac('sha256', Buffer.from(secret, 'utf8'));
hmac.update(buf);
return hmac.digest('hex');
}
What I have currently done is:
Mac sha256_HMAC = Mac.getInstance("HmacSHA256");
SecretKeySpec secret_key = new SecretKeySpec(secret.getBytes(), "HmacSHA256");
sha256_HMAC.init(secret_key);
String hash = Base64.encodeBase64String(sha256_HMAC.doFinal(message.getBytes()));
System.out.println(hash);
This is not working out to be the same.
It's my suspicion that hmac.digest('hex'); isn't base 64 encoded. I'd try converting the response of sha256_HMAC.doFinal(message.getBytes()) to hex instead.
How to convert a byte array to a hex string in Java? 's
The answer I would prefer there (since I use Guava in many projects) is
final String hex = BaseEncoding.base16().lowerCase().encode(bytes);
Adapted to your question would be
final String hash = BaseEncoding.base16().lowerCase().encode(sha256_HMAC.doFinal(message.getBytes()));
Mac sha256_HMAC;
sha256_HMAC = Mac.getInstance("HmacSHA256");
SecretKeySpec secret_key = new SecretKeySpec(secret.getBytes("UTF-8"), "HmacSHA256");
sha256_HMAC.init(secret_key);
byte[] hash = sha256_HMAC.doFinal(payload.getBytes());
return new String(Hex.encodeHex(hash));
Related
I have some java code I have been asked to convert to Python2.7 I have looked online and dont find a good example.
The Java code is building a signature using SecretKeySpec function and HmacSHA256.
It takes a keyString as parameter and a message string a
Below is the function I need to convert to Python:
public static String genSig(String key, String Params) throws Exception {
byte[] decodedKey = Base64.getDecoder().decode(key);
SecretKey originalKey = new SecretKeySpec(decodedKey, 0, decodedKey.length, "HmacSHA256");
Mac hmacSha256 = Mac.getInstance("HmacSHA256");
hmacSha256.init(originalKey);
hmacSha256.update(Params.getBytes());
byte[] HmachSha256DigestBytes = hmacSha256.doFinal();
return Base64.getEncoder().encodeToString(HmachSha256DigestBytes);
}
I have looked into hmac and the hashlib libraries, but Im not sure what to use from these libraries to fulfill this conversion?
You can use the following code:
import hmac
import hashlib
import base64
def generateSignatureFromParams(key, params):
dig = hmac.new(base64.b64decode(key), msg=params, digestmod=hashlib.sha256).digest()
return base64.b64encode(dig).decode()
print generateSignatureFromParams("a2V5", "encrypt")
Notice to get HMACSha256, the digestmod=hashlib.sha256 is important.
Some background of what I'm trying to accomplish.
Part 1.
PHP server communicates with a Java-based device. PHP uses OpenSSL to generate a public/private keypair, then sends the public key to the device which in turn gives back an encrypted macKey (generated using the public key), encoded in base64. PHP now needs to base64-decode and decrypt the macKey using the private key.
What is the equivalent of the below Java code snippet in PHP?
String base64EncodedMacKey = "LkvTT9LFj5lcxRRB8KrwwN906fSIDDcJvQK3E7a5PbR+Ox9WnslOs32jSCC9FkE8ouvr2MfWwtppuZmoPjaxwg3yAQI4UN3T1loISuF2VwKWfJ45fywbK9bNnD5Cw7336mjoGctv77Tg3JXPrsRwgMGIlBsNwdt1B0wgT4MMMAjl32TnBI3iwQ94VTMHffrK+QToddTahRHHoVsr3FVrETdiqKXdkiX1jES53im5lrXYIsY89UFkGzPo+3u4ijKIQWSLvYnA5wXI128gFHKxKYS82MbJDUn9i1RVFsGaP6T3nQRSX5SZNpSe5yGFWwMgYOx0KXMgET82FeaL2hfWuw==";
byte[] base64DecodedMacKey = DatatypeConverter.parseBase64Binary(base64EncodedMacKey);
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.DECRYPT_MODE, keypair.getPrivate());
byte[] macKey = cipher.doFinal(base64DecodedMacKey);
Here's what I attempted in PHP, however I'm confused about using byte array versus string when decrypting the macKey
$macKey = 'LkvTT9LFj5lcxRRB8KrwwN906fSIDDcJvQK3E7a5PbR+Ox9WnslOs32jSCC9FkE8ouvr2MfWwtppuZmoPjaxwg3yAQI4UN3T1loISuF2VwKWfJ45fywbK9bNnD5Cw7336mjoGctv77Tg3JXPrsRwgMGIlBsNwdt1B0wgT4MMMAjl32TnBI3iwQ94VTMHffrK+QToddTahRHHoVsr3FVrETdiqKXdkiX1jES53im5lrXYIsY89UFkGzPo+3u4ijKIQWSLvYnA5wXI128gFHKxKYS82MbJDUn9i1RVFsGaP6T3nQRSX5SZNpSe5yGFWwMgYOx0KXMgET82FeaL2hfWuw==';
$base64DecodedMacKey = base64_decode($macKey);
openssl_private_decrypt($base64DecodedMacKey, $decrypted, $privateKey);
The $decrypted above holds some binary data as it appears, so I'm unsure whether I need to convert it into a byte array or treat it as a string...
Part 2.
Each request has a counter. The macKey in Java code above is used to create a MAC value out of the counter.
What is the equivalent of the below Java code snippet in PHP?
int counter = 0;
String nextCounter = String.valueOf(++counter);
SecretKeySpec signingKey = new SecretKeySpec(macKey, "AES");
Mac mac = Mac.getInstance("HmacSHA256");
mac.init(signingKey);
byte[] counterMac = mac.doFinal(nextCounter.getBytes("UTF-8"));
String base64EncodedMac = DatatypeConverter.printBase64Binary(counterMac);
The base64EncodedMac above is finally sent to the device to validate communication.
I've tried googling different solutions, however I've not been successful in generating a valid base64EncodedMac string in PHP for the device to approve it.
Found the solution myself. For Part 1, I chose to use phpseclib to generate the public/private keys and to specify the encryption algorithm. Decrypting macKey:
$rsa = new Crypt_RSA();
$keys = $rsa->createKey(2048);
// [...]
$macKey = base64_decode($base64EncodedMacKey);
$rsa->setEncryptionMode(CRYPT_RSA_ENCRYPTION_PKCS1);
$rsa->loadKey($keys['privatekey']);
$decryptedMac = $rsa->decrypt($macKey);
Followed by Part 2:
$counter = 0;
$hmac = hash_hmac('sha256', ++$counter, $decryptedMac, true);
$counterMac = base64_encode($hmac);
The main confusing part was that in Java, HMAC was done out of byte array, while in PHP the hash_hmac function expects a String as its 2nd parameter, so using unpack() was not sufficient. However, it seems to have worked with passing the $counter directly. It was also important to use the 4th parameter as TRUE to return raw data.
I am using the following code in c# for HMAC conversion:
string RawData = "data";
string sharedKey = "my-key";
byte[] signature = Encoding.UTF8.GetBytes(RawData);
var KeyByteArray = Encoding.UTF8.GetBytes(sharedKey);
using (HMACSHA256 hmac = new HMACSHA256(KeyByteArray))
{
byte[] signatureBytes =hmac.ComputeHash(signature);
var ContentBase64String =(Convert.ToBase64String(signatureBytes));
Console.WriteLine(ContentBase64String );
Console.ReadKey();
}
And the following in Java:
String RawData="data";
String Key="my-key";
byte[] KeyByteArray=Key.getBytes("UTF-8");
byte[] signature=RawData.getBytes("UTF-8");
Mac sha256_HMAC;
sha256_HMAC = Mac.getInstance("HmacSHA256");
SecretKeySpec secret_key = new SecretKeySpec(KeyByteArray, "HmacSHA256");
sha256_HMAC.init(secret_key);
String ContentBase64String = Base64.encodeToString(sha256_HMAC.doFinal(signature),Base64.URL_SAFE|Base64.NO_WRAP);
The output for C# is as follows:
The output for android is as follows:
I have been it at it for many days and can't figure out what I am doing wrong as the outputs differ though they should be the same.Also, when I remove the - in the key the results are the same. I know I might be missing something simple but thought another pair of eyes might see my mistake. Thanks.
Those answers are the same (as far as the bytes contained in the HMAC goes). For the difference in the + and - characters in the output, you specifically told it to do that by specifying the Base64.URL_SAFE flag.
For future readers of this question: When in doubt, consult the documentation for everything you don't perfectly understand.
I am now trying to encode the string using HMAC-SHA256 using Java. The encoded string required to match another set of encoded string generated by Python using hmac.new(mySecret, myPolicy, hashlib.sha256).hexdigest(). I have tried
Mac sha256_HMAC = Mac.getInstance("HmacSHA256");
SecretKeySpec secretKey = new SecretKeySpec(secret.getBytes(), "HmacSHA256");
sha256_HMAC.init(secretKey);
byte[] hash = sha256_HMAC.doFinal(policy.getBytes());
byte[] hexB = new Hex().encode(hash);
String check = Hex.encodeHexString(hash);
String sha256 = DigestUtils.sha256Hex(secret.getBytes());
after I print them out, hash, hexB, check and sha256 didn't provide the same result as the following Python encryption method
hmac.new(mySecret, myPolicy, hashlib.sha256).hexdigest()
So, I have try to looking for the library or something that work similar to the above Python function. Can anybody help me out?
Are you sure your key and input are identical and correctly encoded in both java and python?
HMAC-SHA256 works the same on both platforms.
Java
Mac sha256_HMAC = Mac.getInstance("HmacSHA256");
SecretKeySpec secretKey = new SecretKeySpec("1234".getBytes(), "HmacSHA256");
sha256_HMAC.init(secretKey);
byte[] hash = sha256_HMAC.doFinal("test".getBytes());
String check = Hex.encodeHexString(hash);
System.out.println(new String(check));
Output
24c4f0295e1bea74f9a5cb5bc40525c8889d11c78c4255808be00defe666671f
Python
print hmac.new("1234", "test", hashlib.sha256).hexdigest();
Output
24c4f0295e1bea74f9a5cb5bc40525c8889d11c78c4255808be00defe666671f
I'm testing my Hmac with test vectors from https://www.rfc-editor.org/rfc/rfc4231
But on test case 3 "Test with a combined length of key and data that is larger than 64 bytes (= block-size of SHA-224 and SHA-256)." I get a different digest than the correct one.
byte[] key = hexify("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
byte[] data = hexify("dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd");
byte[] correct = hexify("773ea91e36800e46854db8ebd09181a72959098b3ef8c122d9635514ced565fe");
// Create digest
SecretKey macKey = new SecretKeySpec(key, "HmacSHA256");
Mac mac = Mac.getInstance("HmacSHA256");
mac.init(macKey);
byte[] digest = mac.doFinal(data);
Any idea why they become different? What did I miss? I'm very new to this.
// Hex encoded
a5418172bb54bf71f3ec28d1c9f34c48da17007eac4d0ca9e2f8ab54b91603e8
773ea91e36800e46854db8ebd09181a72959098b3ef8c122d9635514ced565fe
I can't reproduce your issue. For me, the following SSCCE works just fine:
public static void main(String[] args) throws Exception {
byte[] key = hexify("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
byte[] data = hexify("dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd");
byte[] correct = hexify("773ea91e36800e46854db8ebd09181a72959098b3ef8c122d9635514ced565fe");
// Create digest
SecretKey macKey = new SecretKeySpec(key, "HmacSHA256");
Mac mac = Mac.getInstance("HmacSHA256");
mac.init(macKey);
byte[] digest = mac.doFinal(data);
System.out.println(Arrays.equals(correct, digest));
}
private static byte[] hexify(String string) {
return DatatypeConverter.parseHexBinary(string);
}
Prints: true
Perhaps an error in your display or comparison code?