Create HMAC Hashes Online Generate HMAC digests with multiple hash algorithms.

The tool uses the CryptoJS library to implement seven different hash functions for generating message authentication codes, including HmacMD5, HmacSHA1, HmacSHA256, HmacSHA384, HmacSHA512, HmacSHA3, and HmacRIPEMD160. These functions take two inputs: a message and a secret key, which are combined using the XOR operation with ipad and opad constants to produce an inner and outer hash. The resulting HMAC is then returned as a hexadecimal string. When a user selects an algorithm from the list of available options, it updates the state variable `algorithm` to store the chosen value, which determines the specific hash function used for computation.

The dual-hash construction approach secures even vulnerable hashes by first hashing the key with the message and then combining this result with another hashed version of the key. This process resists length-extension attacks that could otherwise compromise the integrity of the generated HMAC. In cases where keys exceed the block size, they are hashed first to produce a fixed-size output before being used in the HMAC computation. The React library is utilized for building the user interface and managing state changes when users interact with input fields or buttons.

The `hmacFns` object stores references to each hash function implemented by CryptoJS, allowing it to look up and invoke the correct function based on the currently selected algorithm. When a user clicks the "Copy HMAC" button, it calls the `handleCopy` function which attempts to copy the generated HMAC output to the clipboard using the `copyToClipboard` utility function from the `@/lib/utils` module. If copying is successful, it temporarily displays a confirmation message indicating that the HMAC has been copied.

The tool uses JavaScript's built-in support for asynchronous operations and React's state management features to handle user input and update the display of generated HMAC values in real-time as users type or change algorithm selections. It runs entirely on the client-side due to its 'use client' directive, meaning all computations are performed locally within a web browser without transmitting sensitive information over networks. This implementation also adheres to best practices for security by ensuring that secret keys and messages remain confidential throughout the HMAC generation process.