vss-client 0.3.1

// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
// You may not use this file except in accordance with one or both of these
// licenses.

// This is a port of Andrew Moons poly1305-donna
// https://github.com/floodyberry/poly1305-donna

use core::cmp::min;
use core::convert::TryInto;

#[derive(Clone, Copy)]
pub struct Poly1305 {
	r: [u32; 5],
	h: [u32; 5],
	pad: [u32; 4],
	leftover: usize,
	buffer: [u8; 16],
	finalized: bool,
}

#[allow(dead_code, unused)]
impl Poly1305 {
	pub fn new(key: &[u8]) -> Poly1305 {
		assert!(key.len() == 32);
		let mut poly = Poly1305 {
			r: [0u32; 5],
			h: [0u32; 5],
			pad: [0u32; 4],
			leftover: 0,
			buffer: [0u8; 16],
			finalized: false,
		};

		// r &= 0xffffffc0ffffffc0ffffffc0fffffff
		poly.r[0] = (u32::from_le_bytes(key[0..4].try_into().expect("len is 4"))) & 0x3ffffff;
		poly.r[1] = (u32::from_le_bytes(key[3..7].try_into().expect("len is 4")) >> 2) & 0x3ffff03;
		poly.r[2] = (u32::from_le_bytes(key[6..10].try_into().expect("len is 4")) >> 4) & 0x3ffc0ff;
		poly.r[3] = (u32::from_le_bytes(key[9..13].try_into().expect("len is 4")) >> 6) & 0x3f03fff;
		poly.r[4] =
			(u32::from_le_bytes(key[12..16].try_into().expect("len is 4")) >> 8) & 0x00fffff;

		poly.pad[0] = u32::from_le_bytes(key[16..20].try_into().expect("len is 4"));
		poly.pad[1] = u32::from_le_bytes(key[20..24].try_into().expect("len is 4"));
		poly.pad[2] = u32::from_le_bytes(key[24..28].try_into().expect("len is 4"));
		poly.pad[3] = u32::from_le_bytes(key[28..32].try_into().expect("len is 4"));

		poly
	}

	fn block(&mut self, m: &[u8]) {
		let hibit: u32 = if self.finalized { 0 } else { 1 << 24 };

		let r0 = self.r[0];
		let r1 = self.r[1];
		let r2 = self.r[2];
		let r3 = self.r[3];
		let r4 = self.r[4];

		let s1 = r1 * 5;
		let s2 = r2 * 5;
		let s3 = r3 * 5;
		let s4 = r4 * 5;

		let mut h0 = self.h[0];
		let mut h1 = self.h[1];
		let mut h2 = self.h[2];
		let mut h3 = self.h[3];
		let mut h4 = self.h[4];

		// h += m
		h0 += (u32::from_le_bytes(m[0..4].try_into().expect("len is 4"))) & 0x3ffffff;
		h1 += (u32::from_le_bytes(m[3..7].try_into().expect("len is 4")) >> 2) & 0x3ffffff;
		h2 += (u32::from_le_bytes(m[6..10].try_into().expect("len is 4")) >> 4) & 0x3ffffff;
		h3 += (u32::from_le_bytes(m[9..13].try_into().expect("len is 4")) >> 6) & 0x3ffffff;
		h4 += (u32::from_le_bytes(m[12..16].try_into().expect("len is 4")) >> 8) | hibit;

		// h *= r
		let d0 = (h0 as u64 * r0 as u64)
			+ (h1 as u64 * s4 as u64)
			+ (h2 as u64 * s3 as u64)
			+ (h3 as u64 * s2 as u64)
			+ (h4 as u64 * s1 as u64);
		let mut d1 = (h0 as u64 * r1 as u64)
			+ (h1 as u64 * r0 as u64)
			+ (h2 as u64 * s4 as u64)
			+ (h3 as u64 * s3 as u64)
			+ (h4 as u64 * s2 as u64);
		let mut d2 = (h0 as u64 * r2 as u64)
			+ (h1 as u64 * r1 as u64)
			+ (h2 as u64 * r0 as u64)
			+ (h3 as u64 * s4 as u64)
			+ (h4 as u64 * s3 as u64);
		let mut d3 = (h0 as u64 * r3 as u64)
			+ (h1 as u64 * r2 as u64)
			+ (h2 as u64 * r1 as u64)
			+ (h3 as u64 * r0 as u64)
			+ (h4 as u64 * s4 as u64);
		let mut d4 = (h0 as u64 * r4 as u64)
			+ (h1 as u64 * r3 as u64)
			+ (h2 as u64 * r2 as u64)
			+ (h3 as u64 * r1 as u64)
			+ (h4 as u64 * r0 as u64);

		// (partial) h %= p
		let mut c: u32;
		c = (d0 >> 26) as u32;
		h0 = d0 as u32 & 0x3ffffff;
		d1 += c as u64;
		c = (d1 >> 26) as u32;
		h1 = d1 as u32 & 0x3ffffff;
		d2 += c as u64;
		c = (d2 >> 26) as u32;
		h2 = d2 as u32 & 0x3ffffff;
		d3 += c as u64;
		c = (d3 >> 26) as u32;
		h3 = d3 as u32 & 0x3ffffff;
		d4 += c as u64;
		c = (d4 >> 26) as u32;
		h4 = d4 as u32 & 0x3ffffff;
		h0 += c * 5;
		c = h0 >> 26;
		h0 = h0 & 0x3ffffff;
		h1 += c;

		self.h[0] = h0;
		self.h[1] = h1;
		self.h[2] = h2;
		self.h[3] = h3;
		self.h[4] = h4;
	}

	pub fn finish(&mut self) {
		if self.leftover > 0 {
			self.buffer[self.leftover] = 1;
			for i in self.leftover + 1..16 {
				self.buffer[i] = 0;
			}
			self.finalized = true;
			let tmp = self.buffer;
			self.block(&tmp);
		}

		// fully carry h
		let mut h0 = self.h[0];
		let mut h1 = self.h[1];
		let mut h2 = self.h[2];
		let mut h3 = self.h[3];
		let mut h4 = self.h[4];

		let mut c: u32;
		c = h1 >> 26;
		h1 = h1 & 0x3ffffff;
		h2 += c;
		c = h2 >> 26;
		h2 = h2 & 0x3ffffff;
		h3 += c;
		c = h3 >> 26;
		h3 = h3 & 0x3ffffff;
		h4 += c;
		c = h4 >> 26;
		h4 = h4 & 0x3ffffff;
		h0 += c * 5;
		c = h0 >> 26;
		h0 = h0 & 0x3ffffff;
		h1 += c;

		// compute h + -p
		let mut g0 = h0.wrapping_add(5);
		c = g0 >> 26;
		g0 &= 0x3ffffff;
		let mut g1 = h1.wrapping_add(c);
		c = g1 >> 26;
		g1 &= 0x3ffffff;
		let mut g2 = h2.wrapping_add(c);
		c = g2 >> 26;
		g2 &= 0x3ffffff;
		let mut g3 = h3.wrapping_add(c);
		c = g3 >> 26;
		g3 &= 0x3ffffff;
		let mut g4 = h4.wrapping_add(c).wrapping_sub(1 << 26);

		// select h if h < p, or h + -p if h >= p
		let mut mask = (g4 >> (32 - 1)).wrapping_sub(1);
		g0 &= mask;
		g1 &= mask;
		g2 &= mask;
		g3 &= mask;
		g4 &= mask;
		mask = !mask;
		h0 = (h0 & mask) | g0;
		h1 = (h1 & mask) | g1;
		h2 = (h2 & mask) | g2;
		h3 = (h3 & mask) | g3;
		h4 = (h4 & mask) | g4;

		// h = h % (2^128)
		h0 = ((h0) | (h1 << 26)) & 0xffffffff;
		h1 = ((h1 >> 6) | (h2 << 20)) & 0xffffffff;
		h2 = ((h2 >> 12) | (h3 << 14)) & 0xffffffff;
		h3 = ((h3 >> 18) | (h4 << 8)) & 0xffffffff;

		// h = mac = (h + pad) % (2^128)
		let mut f: u64;
		f = h0 as u64 + self.pad[0] as u64;
		h0 = f as u32;
		f = h1 as u64 + self.pad[1] as u64 + (f >> 32);
		h1 = f as u32;
		f = h2 as u64 + self.pad[2] as u64 + (f >> 32);
		h2 = f as u32;
		f = h3 as u64 + self.pad[3] as u64 + (f >> 32);
		h3 = f as u32;

		self.h[0] = h0;
		self.h[1] = h1;
		self.h[2] = h2;
		self.h[3] = h3;
	}

	pub fn input(&mut self, data: &[u8]) {
		assert!(!self.finalized);
		let mut m = data;

		if self.leftover > 0 {
			let want = min(16 - self.leftover, m.len());
			for i in 0..want {
				self.buffer[self.leftover + i] = m[i];
			}
			m = &m[want..];
			self.leftover += want;

			if self.leftover < 16 {
				return;
			}

			// self.block(self.buffer[..]);
			let tmp = self.buffer;
			self.block(&tmp);

			self.leftover = 0;
		}

		while m.len() >= 16 {
			self.block(&m[0..16]);
			m = &m[16..];
		}

		for i in 0..m.len() {
			self.buffer[i] = m[i];
		}
		self.leftover = m.len();
	}

	pub fn raw_result(&mut self, output: &mut [u8]) {
		assert!(output.len() >= 16);
		if !self.finalized {
			self.finish();
		}
		output[0..4].copy_from_slice(&self.h[0].to_le_bytes());
		output[4..8].copy_from_slice(&self.h[1].to_le_bytes());
		output[8..12].copy_from_slice(&self.h[2].to_le_bytes());
		output[12..16].copy_from_slice(&self.h[3].to_le_bytes());
	}
}

#[cfg(test)]
mod test {
	use core::iter::repeat;

	use crate::crypto::poly1305::Poly1305;

	fn poly1305(key: &[u8], msg: &[u8], mac: &mut [u8]) {
		let mut poly = Poly1305::new(key);
		poly.input(msg);
		poly.raw_result(mac);
	}

	#[test]
	fn test_nacl_vector() {
		let key = [
			0xee, 0xa6, 0xa7, 0x25, 0x1c, 0x1e, 0x72, 0x91, 0x6d, 0x11, 0xc2, 0xcb, 0x21, 0x4d,
			0x3c, 0x25, 0x25, 0x39, 0x12, 0x1d, 0x8e, 0x23, 0x4e, 0x65, 0x2d, 0x65, 0x1f, 0xa4,
			0xc8, 0xcf, 0xf8, 0x80,
		];

		let msg = [
			0x8e, 0x99, 0x3b, 0x9f, 0x48, 0x68, 0x12, 0x73, 0xc2, 0x96, 0x50, 0xba, 0x32, 0xfc,
			0x76, 0xce, 0x48, 0x33, 0x2e, 0xa7, 0x16, 0x4d, 0x96, 0xa4, 0x47, 0x6f, 0xb8, 0xc5,
			0x31, 0xa1, 0x18, 0x6a, 0xc0, 0xdf, 0xc1, 0x7c, 0x98, 0xdc, 0xe8, 0x7b, 0x4d, 0xa7,
			0xf0, 0x11, 0xec, 0x48, 0xc9, 0x72, 0x71, 0xd2, 0xc2, 0x0f, 0x9b, 0x92, 0x8f, 0xe2,
			0x27, 0x0d, 0x6f, 0xb8, 0x63, 0xd5, 0x17, 0x38, 0xb4, 0x8e, 0xee, 0xe3, 0x14, 0xa7,
			0xcc, 0x8a, 0xb9, 0x32, 0x16, 0x45, 0x48, 0xe5, 0x26, 0xae, 0x90, 0x22, 0x43, 0x68,
			0x51, 0x7a, 0xcf, 0xea, 0xbd, 0x6b, 0xb3, 0x73, 0x2b, 0xc0, 0xe9, 0xda, 0x99, 0x83,
			0x2b, 0x61, 0xca, 0x01, 0xb6, 0xde, 0x56, 0x24, 0x4a, 0x9e, 0x88, 0xd5, 0xf9, 0xb3,
			0x79, 0x73, 0xf6, 0x22, 0xa4, 0x3d, 0x14, 0xa6, 0x59, 0x9b, 0x1f, 0x65, 0x4c, 0xb4,
			0x5a, 0x74, 0xe3, 0x55, 0xa5,
		];

		let expected = [
			0xf3, 0xff, 0xc7, 0x70, 0x3f, 0x94, 0x00, 0xe5, 0x2a, 0x7d, 0xfb, 0x4b, 0x3d, 0x33,
			0x05, 0xd9,
		];

		let mut mac = [0u8; 16];
		poly1305(&key, &msg, &mut mac);
		assert_eq!(&mac[..], &expected[..]);

		let mut poly = Poly1305::new(&key);
		poly.input(&msg[0..32]);
		poly.input(&msg[32..96]);
		poly.input(&msg[96..112]);
		poly.input(&msg[112..120]);
		poly.input(&msg[120..124]);
		poly.input(&msg[124..126]);
		poly.input(&msg[126..127]);
		poly.input(&msg[127..128]);
		poly.input(&msg[128..129]);
		poly.input(&msg[129..130]);
		poly.input(&msg[130..131]);
		poly.raw_result(&mut mac);
		assert_eq!(&mac[..], &expected[..]);
	}

	#[test]
	fn donna_self_test() {
		let wrap_key = [
			0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00,
		];

		let wrap_msg = [
			0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
			0xff, 0xff,
		];

		let wrap_mac = [
			0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00,
		];

		let mut mac = [0u8; 16];
		poly1305(&wrap_key, &wrap_msg, &mut mac);
		assert_eq!(&mac[..], &wrap_mac[..]);

		let total_key = [
			0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0xff, 0xfe, 0xfd, 0xfc, 0xfb, 0xfa, 0xf9,
			0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
			0x00, 0x00, 0x00, 0x00,
		];

		let total_mac = [
			0x64, 0xaf, 0xe2, 0xe8, 0xd6, 0xad, 0x7b, 0xbd, 0xd2, 0x87, 0xf9, 0x7c, 0x44, 0x62,
			0x3d, 0x39,
		];

		let mut tpoly = Poly1305::new(&total_key);
		for i in 0..256 {
			let key: Vec<u8> = repeat(i as u8).take(32).collect();
			let msg: Vec<u8> = repeat(i as u8).take(256).collect();
			let mut mac = [0u8; 16];
			poly1305(&key[..], &msg[0..i], &mut mac);
			tpoly.input(&mac);
		}
		tpoly.raw_result(&mut mac);
		assert_eq!(&mac[..], &total_mac[..]);
	}

	#[test]
	fn test_tls_vectors() {
		// from http://tools.ietf.org/html/draft-agl-tls-chacha20poly1305-04
		let key = b"this is 32-byte key for Poly1305";
		let msg = [0u8; 32];
		let expected = [
			0x49, 0xec, 0x78, 0x09, 0x0e, 0x48, 0x1e, 0xc6, 0xc2, 0x6b, 0x33, 0xb9, 0x1c, 0xcc,
			0x03, 0x07,
		];
		let mut mac = [0u8; 16];
		poly1305(key, &msg, &mut mac);
		assert_eq!(&mac[..], &expected[..]);

		let msg = b"Hello world!";
		let expected = [
			0xa6, 0xf7, 0x45, 0x00, 0x8f, 0x81, 0xc9, 0x16, 0xa2, 0x0d, 0xcc, 0x74, 0xee, 0xf2,
			0xb2, 0xf0,
		];
		poly1305(key, msg, &mut mac);
		assert_eq!(&mac[..], &expected[..]);
	}
}