Understanding BLAKE2 Hash and MAC Algorithm

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Today we’re going to dive deep into one of the most popular hash functions out there: BLAKE2.

First off, what makes BLAKE2 so special. Unlike its predecessors, it has a variable output size and can be used as both a hash function and a message authentication code (MAC). This means that you can use it for everything from securely storing passwords to verifying the integrity of data in transit.

But enough with the marketing spiel! Let’s get into the details. BLAKE2 is based on a cryptographic hash function called BLAKE, which was designed by Jean-Philippe Aumasson and Sylvain Pelletier back in 2012. The original BLAKE algorithm had some limitations that made it less than ideal for certain use cases, so the team went back to the drawing board and came up with a new version called BLAKE2.

BLAKE2 is designed to be faster and more efficient than its predecessors while still maintaining a high level of security. It uses a sponge construction that allows it to process data in chunks, which makes it ideal for use in real-time applications like streaming media or network traffic analysis.

So how does BLAKE2 actually work? Well, let’s take a look at the algorithm itself:

1. Initialize the state with an initial value (IV) and a key (if using MAC mode).

2. Divide the input data into 512-bit chunks called blocks.

3. For each block:
Expand it to create two new 1088-bit values, XL and XR.
Compute a series of rounds using these expanded values and the current state.
Update the state with the output from the rounds.

4. If there are any remaining bytes in the input data:
Pad them to create a final block.
Expand this final block to create two new 1088-bit values, XL and XR.
Compute a series of rounds using these expanded values and the current state.
Update the state with the output from the rounds.

5. If using MAC mode:
Append the key to the final block (if not already included).
Expand this final block to create two new 1088-bit values, XL and XR.
Compute a series of rounds using these expanded values and the current state.
Update the state with the output from the rounds.

6. If using hash mode:
Output the final state as the hash value (truncated to the desired size).

7. If using MAC mode:
Compute a series of additional rounds using the current state and the key.
XOR the output from these additional rounds with the input data to create the MAC tag.

And that’s it! BLAKE2 is designed to be simple, efficient, and secure. It can handle inputs up to 1GB in size (with a maximum hash/MAC length of 512 bits) and has been thoroughly tested for security vulnerabilities.

So why should you care about BLAKE2? Well, if you’re working on any kind of cryptographic application that requires secure data storage or transmission, then it’s definitely worth considering. It’s faster than SHA-1 and MD5 (which are both being phased out due to security concerns), and it has a variable output size which makes it more flexible for different use cases.

But don’t just take our word for it! Here’s an example of how you can implement BLAKE2 in Python using the cryptography library:

# Import the necessary libraries
import hashlib # Importing the hashlib library for cryptographic hashing functions
from cryptography.hazmat.primitives import hashes, macs # Importing the necessary modules from the cryptography library
from cryptography.hazmat.backends import default_backend # Importing the default backend for cryptography

# Define a function for BLAKE2b
def blake2b(data):
    # Initialize BLAKE2b with a 256-bit output size (default is 160-bit)
    hash = hashes.Hash(hashes.BLAKE2b(digest_size=256), backend=default_backend()) # Creating a BLAKE2b hash object with a 256-bit output size
    hash.update(data) # Updating the hash object with the input data
    return hash.finalize() # Returning the final hash value

# Define a function for BLAKE2s
def blake2s(key, data):
    # Initialize BLAKE2s with a 256-bit output size (default is 128-bit) and key
    mac = macs.MAC(hashes.BLAKE2s(digest_size=256), backend=default_backend()) # Creating a BLAKE2s MAC object with a 256-bit output size
    mac.update(key) # Updating the MAC object with the key
    mac.update(data) # Updating the MAC object with the input data
    return mac.finalize() # Returning the final MAC value

And that’s it! You can use these functions to hash or authenticate data using BLAKE2 in your Python applications.

We hope this has been helpful for all of our crypto-curious readers out there. Until next time, keep on hacking!

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