From 1ade62b630f565d975049aa75935c64db175ef61 Mon Sep 17 00:00:00 2001
From: Yawning Angel <yawning@schwanenlied.me>
Date: Mon, 27 May 2024 21:25:26 +0900
Subject: core/crypto/_aes/ct64: Add GHASH

---
 core/crypto/_aes/aes.odin        |   5 ++
 core/crypto/_aes/ct64/ghash.odin | 136 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 141 insertions(+)
 create mode 100644 core/crypto/_aes/ct64/ghash.odin

diff --git a/core/crypto/_aes/aes.odin b/core/crypto/_aes/aes.odin
index 74906fcd4..6b290feb6 100644
--- a/core/crypto/_aes/aes.odin
+++ b/core/crypto/_aes/aes.odin
@@ -18,5 +18,10 @@ ROUNDS_192 :: 12
 // ROUNDS_256 is the number of rounds for AES-256.
 ROUNDS_256 :: 14
 
+// GHASH_KEY_SIZE is the GHASH key size in bytes.
+GHASH_KEY_SIZE :: 16
+// GHASH_BLOCK_SIZE is the GHASH block size in bytes.
+GHASH_BLOCK_SIZE :: 16
+
 // RCON is the AES keyschedule round constants.
 RCON := [10]byte{0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1B, 0x36}
diff --git a/core/crypto/_aes/ct64/ghash.odin b/core/crypto/_aes/ct64/ghash.odin
new file mode 100644
index 000000000..21ac2ca97
--- /dev/null
+++ b/core/crypto/_aes/ct64/ghash.odin
@@ -0,0 +1,136 @@
+// Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+//
+//   1. Redistributions of source code must retain the above copyright
+//      notice, this list of conditions and the following disclaimer.
+//
+// THIS SOFTWARE IS PROVIDED BY THE AUTHORS “AS IS” AND ANY EXPRESS OR
+// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
+// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
+// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package aes_ct64
+
+import "base:intrinsics"
+import "core:crypto/_aes"
+import "core:encoding/endian"
+
+@(private = "file")
+bmul64 :: proc "contextless" (x, y: u64) -> u64 {
+	x0 := x & 0x1111111111111111
+	x1 := x & 0x2222222222222222
+	x2 := x & 0x4444444444444444
+	x3 := x & 0x8888888888888888
+	y0 := y & 0x1111111111111111
+	y1 := y & 0x2222222222222222
+	y2 := y & 0x4444444444444444
+	y3 := y & 0x8888888888888888
+	z0 := (x0 * y0) ~ (x1 * y3) ~ (x2 * y2) ~ (x3 * y1)
+	z1 := (x0 * y1) ~ (x1 * y0) ~ (x2 * y3) ~ (x3 * y2)
+	z2 := (x0 * y2) ~ (x1 * y1) ~ (x2 * y0) ~ (x3 * y3)
+	z3 := (x0 * y3) ~ (x1 * y2) ~ (x2 * y1) ~ (x3 * y0)
+	z0 &= 0x1111111111111111
+	z1 &= 0x2222222222222222
+	z2 &= 0x4444444444444444
+	z3 &= 0x8888888888888888
+	return z0 | z1 | z2 | z3
+}
+
+@(private = "file")
+rev64 :: proc "contextless" (x: u64) -> u64 {
+	x := x
+	x = ((x & 0x5555555555555555) << 1) | ((x >> 1) & 0x5555555555555555)
+	x = ((x & 0x3333333333333333) << 2) | ((x >> 2) & 0x3333333333333333)
+	x = ((x & 0x0F0F0F0F0F0F0F0F) << 4) | ((x >> 4) & 0x0F0F0F0F0F0F0F0F)
+	x = ((x & 0x00FF00FF00FF00FF) << 8) | ((x >> 8) & 0x00FF00FF00FF00FF)
+	x = ((x & 0x0000FFFF0000FFFF) << 16) | ((x >> 16) & 0x0000FFFF0000FFFF)
+	return (x << 32) | (x >> 32)
+}
+
+// ghash calculates the GHASH of data, with the key `key`, and input `dst`
+// and `data`, and stores the resulting digest in `dst`.
+//
+// Note: `dst` is both an input and an output, to support easy implementation
+// of GCM.
+ghash :: proc "contextless" (dst, key, data: []byte) {
+	if len(dst) != _aes.GHASH_BLOCK_SIZE || len(key) != _aes.GHASH_BLOCK_SIZE {
+		intrinsics.trap()
+	}
+
+	buf := data
+	l := len(buf)
+
+	y1 := endian.unchecked_get_u64be(dst[0:])
+	y0 := endian.unchecked_get_u64be(dst[8:])
+	h1 := endian.unchecked_get_u64be(key[0:])
+	h0 := endian.unchecked_get_u64be(key[8:])
+	h0r := rev64(h0)
+	h1r := rev64(h1)
+	h2 := h0 ~ h1
+	h2r := h0r ~ h1r
+
+	src: []byte
+	for l > 0 {
+		if l >= _aes.GHASH_BLOCK_SIZE {
+			src = buf
+			buf = buf[_aes.GHASH_BLOCK_SIZE:]
+			l -= _aes.GHASH_BLOCK_SIZE
+		} else {
+			tmp: [_aes.GHASH_BLOCK_SIZE]byte
+			copy(tmp[:], buf)
+			src = tmp[:]
+			l = 0
+		}
+		y1 ~= endian.unchecked_get_u64be(src)
+		y0 ~= endian.unchecked_get_u64be(src[8:])
+
+		y0r := rev64(y0)
+		y1r := rev64(y1)
+		y2 := y0 ~ y1
+		y2r := y0r ~ y1r
+
+		z0 := bmul64(y0, h0)
+		z1 := bmul64(y1, h1)
+		z2 := bmul64(y2, h2)
+		z0h := bmul64(y0r, h0r)
+		z1h := bmul64(y1r, h1r)
+		z2h := bmul64(y2r, h2r)
+		z2 ~= z0 ~ z1
+		z2h ~= z0h ~ z1h
+		z0h = rev64(z0h) >> 1
+		z1h = rev64(z1h) >> 1
+		z2h = rev64(z2h) >> 1
+
+		v0 := z0
+		v1 := z0h ~ z2
+		v2 := z1 ~ z2h
+		v3 := z1h
+
+		v3 = (v3 << 1) | (v2 >> 63)
+		v2 = (v2 << 1) | (v1 >> 63)
+		v1 = (v1 << 1) | (v0 >> 63)
+		v0 = (v0 << 1)
+
+		v2 ~= v0 ~ (v0 >> 1) ~ (v0 >> 2) ~ (v0 >> 7)
+		v1 ~= (v0 << 63) ~ (v0 << 62) ~ (v0 << 57)
+		v3 ~= v1 ~ (v1 >> 1) ~ (v1 >> 2) ~ (v1 >> 7)
+		v2 ~= (v1 << 63) ~ (v1 << 62) ~ (v1 << 57)
+
+		y0 = v2
+		y1 = v3
+	}
+
+	endian.unchecked_put_u64be(dst[0:], y1)
+	endian.unchecked_put_u64be(dst[8:], y0)
+}
-- 
cgit v1.2.3