zig

commit 96793530cd7e3ea8d083a0695f156576b1fbe4e1 (tree)
parent e64eef366c68592f6daf063a8b8f85b8626a1598
Author: Frank Denis <124872+jedisct1@users.noreply.github.com>
Date:   Thu,  3 Nov 2022 13:10:08 +0100

std.crypto.pwhash.bcrypt: inline the Feistel network function (#13416)

std/crypto/benchmark.zig results:

* Intel i5

before: 3.144 s/ops
 after: 1.922 s/ops

* Apple M1

before: 2.067 s/ops
 after: 1.373 s/ops
Diffstat:
M
lib/std/crypto/bcrypt.zig
 | 
18
+++++++-----------

1 file changed, 7 insertions(+), 11 deletions(-)
diff --git a/lib/std/crypto/bcrypt.zig b/lib/std/crypto/bcrypt.zig
@@ -374,22 +374,18 @@ pub const State = struct {
 
     const Halves = struct { l: u32, r: u32 };
 
-    fn feistelF(state: State, x: u32) u32 {
-        var r = state.sboxes[0][@truncate(u8, x >> 24)];
-        r +%= state.sboxes[1][@truncate(u8, x >> 16)];
-        r ^= state.sboxes[2][@truncate(u8, x >> 8)];
-        r +%= state.sboxes[3][@truncate(u8, x)];
-        return r;
-    }
-
     fn halfRound(state: State, i: u32, j: u32, n: usize) u32 {
-        return i ^ state.feistelF(j) ^ state.subkeys[n];
+        var r = state.sboxes[0][@truncate(u8, j >> 24)];
+        r +%= state.sboxes[1][@truncate(u8, j >> 16)];
+        r ^= state.sboxes[2][@truncate(u8, j >> 8)];
+        r +%= state.sboxes[3][@truncate(u8, j)];
+        return i ^ r ^ state.subkeys[n];
     }
 
     fn encipher(state: State, halves: *Halves) void {
         halves.l ^= state.subkeys[0];
-        var i: usize = 1;
-        while (i < 16) : (i += 2) {
+        comptime var i = 1;
+        inline while (i < 16) : (i += 2) {
             halves.r = state.halfRound(halves.r, halves.l, i);
             halves.l = state.halfRound(halves.l, halves.r, i + 1);
         }