[−][src]Crate primes
Explaining
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:
- Every prime generate will be lower than 2^32^.
- We can work with up 2^512^. If every prime is lower than 2^32^, we can use 16 or more hashes.
//! ```toml [dependencies] Gen_Prime = "1.1.3"
#EXAMPLE 1
```rust
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
Introduce a hash
074a4a47c445cf604b2ca687fed09fd8f3a78a16d20786b1a97aa6642fe0f87a8577a52cbace36bab6a6c40c3f1843be
1073741827
Introduce a hash
00eccf559792ee42e3ea26e394e9ab52ce569e47504d44715102cc0c2ab4f542dc54c383e8e13d360ebc57c5ede5e64b
16777259
Introduce a hash
daa41c63b728ba70e6c377d7d17d9e53185fc720e7e6326626608eb1edc3735f67d963c303d92c9196583f3cd8739943
16553
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]); } //this lines are to safe each char in one component of a vector, and to delete white spaces res=primes::hash_to_prime(v2); //Generating a prime mult=mult*(bigint::U512::from(res as usize)); //Product of the primes 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 (d) and r is a rand number that calculates the rth prime in [x,y]. The last number is the product of all primes. Can you find one of the primes? ;)
Functions
hash_to_prime |