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use super::hotp;
use byteorder::{BigEndian, WriteBytesExt};
use std::time::SystemTime;
const TIME_STEP: u64 = 30;
const TOTP_DIGITS: u8 = 6;
// TOTP を現在時刻から計算する
pub fn totp(secret: &[u8]) -> Result<String, String> {
match current_time() {
Ok(current_time) => gen_totp(secret, current_time, TOTP_DIGITS),
Err(err) => Err(err),
}
}
// TOTP を任意の時刻で計算する
fn gen_totp(secret: &[u8], time: u64, digits: u8) -> Result<String, String> {
let t = time / TIME_STEP;
let mut byte_t = Vec::new();
byte_t.write_u64::<BigEndian>(t).unwrap();
hotp::hotp(secret, &byte_t, digits)
}
// UNIX time からの経過秒数を返す
fn current_time() -> Result<u64, String> {
match SystemTime::now().duration_since(SystemTime::UNIX_EPOCH) {
Ok(n) => Ok(n.as_secs()),
Err(_) => Err(String::from("SystemTime before UNIX EPOCH!")),
}
}
#[cfg(test)]
mod tests {
use super::*;
// from RFC6238
// +---+-------------+--------------+------------------+----------+--------+
// | # | Time (sec) | UTC Time | Value of T (hex) | TOTP | Mode |
// |---+-------------+--------------+------------------+----------+--------+
// | 1 | 59 | 1970-01-01 | 0000000000000001 | 94287082 | SHA1 |
// | | | 00:00:59 | | | |
// | 2 | 1111111109 | 2005-03-18 | 00000000023523EC | 07081804 | SHA1 |
// | | | 01:58:29 | | | |
// | 3 | 1111111111 | 2005-03-18 | 00000000023523ED | 14050471 | SHA1 |
// | | | 01:58:31 | | | |
// | 4 | 1234567890 | 2009-02-13 | 000000000273EF07 | 89005924 | SHA1 |
// | | | 23:31:30 | | | |
// | 5 | 2000000000 | 2033-05-18 | 0000000003F940AA | 69279037 | SHA1 |
// | | | 03:33:20 | | | |
// | 6 | 20000000000 | 2603-10-11 | 0000000027BC86AA | 65353130 | SHA1 |
// | | | 11:33:20 | | | |
// +---+-------------+--------------+------------------+----------+--------+
#[test]
fn rfc_6238_1() {
let totp = gen_totp(b"12345678901234567890", 59, 8).unwrap();
assert_eq!(totp, "94287082");
}
#[test]
fn rfc_6238_2() {
let totp = gen_totp(b"12345678901234567890", 1_111_111_109, 8).unwrap();
assert_eq!(totp, "07081804");
}
#[test]
fn rfc_6238_3() {
let totp = gen_totp(b"12345678901234567890", 1_111_111_111, 8).unwrap();
assert_eq!(totp, "14050471");
}
#[test]
fn rfc_6238_4() {
let totp = gen_totp(b"12345678901234567890", 1_234_567_890, 8).unwrap();
assert_eq!(totp, "89005924");
}
#[test]
fn rfc_6238_5() {
let totp = gen_totp(b"12345678901234567890", 2_000_000_000, 8).unwrap();
assert_eq!(totp, "69279037");
}
#[test]
fn rfc_6238_6() {
let totp = gen_totp(b"12345678901234567890", 20_000_000_000, 8).unwrap();
assert_eq!(totp, "65353130");
}
}