BLAKE2 Hash and Message Authentication Code (MAC) Algorithms

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Let’s dive deeper into Blake2 hash algorithm and its Message Authentication Code (MAC) variant. Blake2 is a cryptographic hash function designed by Jean-Philippe Aumasson and Sylvain Pelletier in 2012. It was created to address some of the weaknesses found in earlier hash functions, such as MD5 and SHA-1.

Blake2 offers improved security, faster performance, and better parallelization capabilities compared to its predecessors. The Blake2 hash function uses a mixing function G and compression function F for data processing. The mixing function G is used to combine two input words (x and y) into four output words: a, b, c, and d. This operation involves bitwise rotations, XOR operations, and additions with some fixed constants.
Blake2 MAC is an authenticated encryption algorithm that provides data integrity and confidentiality for messages. It uses the same underlying hash function as Blake2 but adds additional steps to ensure message authentication. The MAC variant of Blake2 can be used in various applications such as secure messaging, file transfer protocols, and network security.
To generate a MAC using Blake2, first, create an initialization vector (IV) for the message. This IV is added to the message before processing it through the hash function. Then, process the message with the hash function and output the resulting digest. Finally, append the IV to the end of the message and compute another digest over the concatenated data. The result is a MAC that can be used to verify the integrity of the original message.
Here’s an example implementation in Python:

import blake2 # Importing the blake2 library for generating hash functions
from binascii import hexlify, unhexlify # Importing the hexlify and unhexlify functions from the binascii library

def generate_mac(message):
    # Generate IV for message
    iv = b'\x01\x02\x03\x04' * 8 # Generating an initialization vector (IV) for the message, which is a sequence of bytes represented by the hexadecimal values 01, 02, 03, and 04, repeated 8 times
    
    # Concatenate IV and message
    data = iv + message # Concatenating the IV and the message to create a single data string
    
    # Initialize hash context with key (optional)
    ctx = blake2.new(key=b'my_secret_key') # Initializing a hash context using the blake2.new() function, with an optional key parameter set to 'my_secret_key' for added security. If no key is provided, the default value is used.
    
    # Update the hash context with concatenated IV and message
    ctx.update(data) # Updating the hash context with the concatenated data string
    
    # Get MAC as hex string
    mac = hexlify(ctx.digest()).decode('utf-8') # Generating a message authentication code (MAC) by converting the digest of the hash context into a hexadecimal string using the hexlify() function, and then decoding it into a UTF-8 string
    
    return mac # Returning the MAC as the output of the function

In this example, we first generate an IV of 64 bytes (eight blocks of four bytes each). We then concatenate the IV and message to create a new data stream for processing by Blake2 hash function. If you want to add confidentiality to your messages, you can also include a secret key in the initialization step using the `key` parameter when creating the hash context.
The resulting MAC is returned as a hexadecimal string that can be used to verify the integrity of the original message. To do this, simply concatenate the IV and message again and compute another digest over the concatenated data. If the result matches the previously generated MAC, then the message has not been tampered with.
In terms of performance, Blake2 is faster than SHA-1 and MD5 for most input sizes due to its parallelization capabilities. It can be used in both hardware and software environments, making it a versatile choice for cryptographic applications. Additionally, Blake2 provides better security compared to earlier hash functions because it uses a larger state size (1024 bits) and has a more complex mixing function.

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