mirror/zig
1
0
Fork 0
mirror of https://github.com/ziglang/zig.git synced 2026-01-21 06:45:24 +00:00
Code Issues Packages Projects Releases Wiki Activity

chacha20poly1305: verify tag in constant time

Browse Source
This commit is contained in:
lukechampine 2019-11-05 11:51:16 -05:00
parent fbe7d8c1cb
commit ae7bb4ecc0
No known key found for this signature in database
GPG Key ID: A5C1CE074CBF1D60
1 changed files with 8 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
lib/std/crypto/chacha20.zig
View File

@ -503,8 +503,14 @@ pub fn chacha20poly1305Open(dst: []u8, ciphertext: []const u8, data: []const u8,
var computedTag: [16]u8 = undefined;
mac.final(computedTag[0..]);
// verify mac
if (!mem.eql(u8, polyTag, computedTag[0..])) {
// verify mac in constant time
// TODO: we can't currently guarantee that this will run in constant time.
// See https://github.com/ziglang/zig/issues/1776
var acc: u8 = 0;
for (computedTag) |_, i| {
acc |= (computedTag[i] ^ polyTag[i]);
}
if (acc != 0) {
return false;
}