Crate primes

Explanation

This is a method that allows calculate a prime number using a hash. The idea is really simple: we generate a number n passing the hash from 16-basis to a special basis, taken the value of tha char in 10-basis and multiply by 2^i, where i is the position of the char in the string. This number n, we calculate the rest module 31, obtaining an other number d. We find the numbers x=2^d-1 and y=2^(d+1)-1. We call a function that returns the first prime nuber in [x,y]. This will be our choice.

We apply module 31 for 2 reasons:

1. Every prime generate will be lower than 2^32.
2. We can work with up 2^512. If every prime is lower than 2^32, we can use 16 or more hashes.

Exemples

extern crate primes;
 
 
    let z:u128;
    println!("Introduce a hash");
    let mut a = String::new();
    std::io::stdin().read_line(&mut a).expect("Fail");
    let v : Vec<&str>=a.split("").collect();
    z=primes::hash_to_prime(v);
    println!("{}", z);
 
 

#Outputs:

Introduce a hash a123dfe4758bc27237a

2147483647

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Introduce a hash 074a4a47c445cf604b2ca687fed09fd8f3a78a16d20786b1a97aa6642fe0f87a8577a52cbace36bab6a6c40c3f1843be

1073741827

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Introduce a hash 00eccf559792ee42e3ea26e394e9ab52ce569e47504d44715102cc0c2ab4f542dc54c383e8e13d360ebc57c5ede5e64b

16777259

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Introduce a hash daa41c63b728ba70e6c377d7d17d9e53185fc720e7e6326626608eb1edc3735f67d963c303d92c9196583f3cd8739943

16553

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EXAMPLE 2

use std::io;
use std::u128;
extern crate bigint;
extern crate primes;
extern crate rand;
use bigint::U512;
 
    let mut mult:bigint::U512;
    mult=U512::one();
    loop{
        println!("Introduce a hash");
        let mut a = String::new();
        std::io::stdin().read_line(&mut a).expect("Fail");
        let v : Vec<&str>=a.split("").collect();
        let n2=v.len() as u32;
        let res:u128;
        let mut v2=Vec::with_capacity((n2-3) as usize);
        for i in 0..n2-3 {
            i as usize;
            v2.push(v[(i+1) as usize]);
        }
        res=primes::hash_to_prime(v2);
        mult=mult*(bigint::U512::from(res as usize));
        println!("Do you want to enter another hash?[Y/N]");
        let mut b = String::new();
        io::stdin().read_line(&mut b).expect("Fail");
        let b : char = b.trim().parse().expect("Please, input one choice");
        if b=='N' || b=='n'{
            break;
        }
    }
    println!("{}", mult);
 

Output

Introduce a hash daa41c63b728ba70e6c377d7d17d9e53185fc720e7e6326626608eb1edc3735f67d963c303d92c9196583f3cd8739943 19 r:100 Do you want to enter another hash?[Y/N] Y Introduce a hash 0907b5ff1b7d6f7b2639ca00565c8f42cbf7529b992f825b2676ec30c294b477b913476d6a508da9d195f1dacc893173 23 r:39 Do you want to enter another hash?[Y/N] Y Introduce a hash 4cb34fd780fbac405a433f428bd5672c0f7003cf1ae9d0675225c8d83783c0fc57e8b1f64a9bad799084f71381d1115e 27 r:55 Do you want to enter another hash?[Y/N] Y Introduce a hash fae89ae85b629f1d5263c7b5ad5035cc72c3cb02f95a9a242f5065f235611863f28fd4798818054e4cf69fd464e7f3b0 8 r:49 Do you want to enter another hash?[Y/N] Y Introduce a hash d0054fddab35b4aa7ab1356811f5c5ef7a1536ccca1ac76549b36030c875c4329d12f86b67591e3d9b3ca7f178861c94 5 r:57 Do you want to enter another hash?[Y/N] N 110277345636720260972118701 where the number after each hash is the value mod 31 and r is a rand number that calculates the rth prime in [x,y]

Functions

hash_to_prime