To start: what is a hash function? Well, it’s basically a mathematical algorithm that takes an input message (like “hello world”) and outputs a fixed-size string of characters called a hash or digest. The cool thing about hashes is that they’re one-way functions you can’t reverse engineer the original message from the output hash. This makes them perfect for securing sensitive data, like passwords or credit card numbers.

Now let’s talk specifically about Blake2s. It was introduced in 2012 by Zooko O’Whielacronx as an alternative to SHA-3 and SHA-2 (which are both pretty outdated). The “s” at the end of Blake2s stands for “streaming,” which means it can handle large amounts of data without having to store everything in memory. This makes it perfect for use cases like streaming video or audio, where you need to hash chunks of data as they come through.

So how does Blake2s work? Well, let’s take a look at the code:

“`c++
// This script demonstrates the use of Blake2s, a cryptographic hash function that is optimized for speed and memory efficiency.

#include
#include “blake2s.h” // include our library for blake2s
using namespace std;

int main() {
const char* message = “hello world”; // set up our input string
unsigned int digest_size = 32; // we’re using the default size of 256 bits (32 bytes)
unsigned char hash[digest_size]; // create a buffer to store our output hash

blake2s(hash, digest_size, message, strlen(message)); // call the function and pass in our arguments
// The blake2s function takes in four arguments: the output buffer, the size of the output hash, the input message, and the length of the input message.

for (int i = 0; i < digest_size; ++i) { // print out each byte of the hash cout << hex << setw(2) << setfill('0') << static_cast(hash[i]) << " "; // use cout to print out each byte of the hash in hexadecimal format } return 0; } // The for loop iterates through each byte of the hash and prints it out in hexadecimal format. // The setw and setfill functions are used to ensure that each byte is printed out with two digits, even if the value is less than 16. // The static_cast function is used to convert the unsigned char value to an unsigned int, which is required for printing in hexadecimal format. ``` As you can see, we're using a library called blake2s.h to handle the actual hash function calculations. We set up our input string and output buffer, then call the `blake2s()` function with our arguments (the output buffer, desired digest size, input message, and length of that message). The resulting hash is stored in the `hash` array, which we print out using a loop to format each byte as hexadecimal. You've just implemented Blake2s in C++. Now some cool features of Blake2s that make it stand out from other hash functions: - It has a variable output size, which means you can choose the length of your digest based on your needs (ranging from 160 bits to 512 bits). This is great for situations where you need more or less security. - It's parallelizable, meaning it can be optimized for multi-core CPUs and GPUs. This makes it super fast when dealing with large amounts of data. - It has a low memory footprint, which means it doesn't require as much RAM to run compared to other hash functions like SHA-256 or MD5. Blake2s is an awesome alternative to traditional hash functions that offers speed, security, and flexibility. Give it a try in your next project and let us know what you think!