Cryptographic hash functions primitives

Via Wikipedia:

The ideal cryptographic hash function has four main properties:

• it is easy to compute the hash value for any given message
• it is infeasible to generate a message from its hash
• it is infeasible to modify a message without changing the hash
• it is infeasible to find two different messages with the same hash.

Example

Calculate SHA-512 sum:

# extern crate octavo_digest;
use octavo_digest::Digest;
use octavo_digest::sha2::Sha512;

# fn main() {
# let data = "Hello World!";
let mut result = vec![0; Sha512::output_bytes()];
let mut sha = Sha512::default();

sha.update(data);
sha.result(&mut result);

for byte in result {
    print!("{:2x}", byte);
}
println!(" {}", data);
# }