Package io.github.pratiyush.totp.internal

Class HMACProvider

java.lang.Object

io.github.pratiyush.totp.internal.HMACProvider

public final class HMACProvider
extends Object

Secure HMAC computation for TOTP.

This utility class provides thread-safe HMAC calculation using the Java Cryptography Architecture (JCA).

Thread Safety

This class is thread-safe. Each call creates a fresh Mac instance.

Security Notes

• Uses standard JCA providers (no external crypto libraries)
• Validates algorithm availability before use
• Clear error messages for debugging (no secret leakage)

Method Summary

Modifier and Type	Method	Description
static byte[]	compute(Algorithm algorithm, byte[] key, byte[] data)	Computes HMAC using the specified algorithm.
static byte[]	compute(String algorithmName, byte[] key, byte[] data)	Computes HMAC using the specified algorithm name.
static boolean	isAlgorithmAvailable(Algorithm algorithm)	Checks if an algorithm is available in the current JVM.
static boolean	isAlgorithmAvailable(String algorithmName)	Checks if an algorithm is available in the current JVM.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

compute

public static byte[] compute(Algorithm algorithm,
 byte[] key,
 byte[] data)
                      throws TOTPException

Computes HMAC using the specified algorithm.

Parameters:

algorithm - the HMAC algorithm

key - the secret key

data - the data to authenticate

Returns:

the HMAC result

Throws:

TOTPException - if HMAC computation fails

compute

public static byte[] compute(String algorithmName,
 byte[] key,
 byte[] data)
                      throws TOTPException

Computes HMAC using the specified algorithm name.

Parameters:

algorithmName - the JCA algorithm name (e.g., "HmacSHA256")

key - the secret key

data - the data to authenticate

Returns:

the HMAC result

Throws:

TOTPException - if HMAC computation fails

isAlgorithmAvailable

public static boolean isAlgorithmAvailable(Algorithm algorithm)

Checks if an algorithm is available in the current JVM.

Parameters:

algorithm - the algorithm to check

Returns:

true if the algorithm is available

isAlgorithmAvailable

public static boolean isAlgorithmAvailable(String algorithmName)

Checks if an algorithm is available in the current JVM.

Parameters:

algorithmName - the JCA algorithm name

Returns:

true if the algorithm is available