Function decrypt 

pub fn decrypt(cyphertext: &[u8], keypair: &Keypair) -> Option<Vec<u8>>

Attempt to decrypt a private-box message, using your secret key. If you were an intended recipient then the decrypted message is returned as Some(Vec<u8>). If it was not for you, then None will be returned.

Example

use private_box::{encrypt, decrypt};
use ssb_crypto::Keypair;

fn main() {
    let msg = "hello!".as_bytes();

    let alice = Keypair::generate();
    let bob = Keypair::generate();

    let recps = [alice.public, bob.public];
    let cypher = encrypt(msg, &recps);

    let alice_result = decrypt(&cypher, &alice);
    let bob_result = decrypt(&cypher, &bob);

    assert_eq!(&alice_result.unwrap(), &msg);
    assert_eq!(&bob_result.unwrap(), &msg);
}