use std::hash::Hasher;
use std::io;
use byteorder::{BigEndian, ByteOrder, WriteBytesExt};
use sha1::{Digest, Sha1};
use crate::pgp::errors::Result;
#[inline]
pub fn simple(actual: &[u8], data: &[u8]) -> Result<()> {
let expected_checksum = calculate_simple(data);
ensure_eq!(
&actual[..2],
&expected_checksum.to_be_bytes()[..],
"invalid simple checksum"
);
Ok(())
}
#[inline]
pub fn simple_to_writer<W: io::Write>(data: &[u8], writer: &mut W) -> io::Result<()> {
let mut hasher = SimpleChecksum::default();
hasher.write(data);
hasher.to_writer(writer)
}
#[inline]
pub fn calculate_simple(data: &[u8]) -> u16 {
let mut hasher = SimpleChecksum::default();
hasher.write(data);
hasher.finish() as u16
}
#[derive(Debug, Default)]
pub struct SimpleChecksum(u16);
impl SimpleChecksum {
#[inline]
pub fn to_writer<W: io::Write>(&self, writer: &mut W) -> io::Result<()> {
writer.write_u16::<BigEndian>(self.0)
}
#[inline]
pub fn finalize(&self) -> [u8; 2] {
let mut res = [0u8; 2];
BigEndian::write_u16(&mut res[..], self.0);
res
}
}
impl io::Write for SimpleChecksum {
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
Hasher::write(self, buf);
Ok(buf.len())
}
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
impl Hasher for SimpleChecksum {
#[inline]
fn write(&mut self, buf: &[u8]) {
let new_sum = buf.iter().map(|v| u32::from(*v)).sum::<u32>();
self.0 = ((u32::from(self.0) + new_sum) & 0xffff) as u16;
}
#[inline]
fn finish(&self) -> u64 {
u64::from(self.0)
}
}
#[inline]
pub fn calculate_sha1(data: &[u8]) -> Vec<u8> {
Sha1::digest(data)[..20].to_vec()
}