Function encrypt_string 

pub fn encrypt_string(
    pk_base64: &String,
    message: &String,
    params: &Parameters,
    seed: Option<u64>,
) -> String

Encrypt a string using the public key

Arguments:

• pk_string - public key as a base64 encoded string
• message - message to encrypt
• params - ring-LWE parameters
• seed - random seed

Returns:

encrypted message as a base64 encoded string

Example:

let params = ring_lwe::utils::Parameters::default();
let keys = ring_lwe::keygen::keygen_string(&params, None);
let pk_string = keys.get("public").unwrap();
let message = String::from("hello");
let ciphertext_string = ring_lwe::encrypt::encrypt_string(pk_string, &message, &params, None);