# HG changeset patch # User Matthew Wild # Date 1620911587 -3600 # Node ID d2f33b8fdc968b594e596d73d200dbfb6679dd02 # Parent 3bbb1af92514131df4a83befc810d97457686479 util.jwt: Use constant-time comparison with expected signature diff -r 3bbb1af92514 -r d2f33b8fdc96 util/jwt.lua --- a/util/jwt.lua Thu May 13 11:17:13 2021 +0100 +++ b/util/jwt.lua Thu May 13 14:13:07 2021 +0100 @@ -3,6 +3,7 @@ local hashes = require "util.hashes"; local base64_encode = require "util.encodings".base64.encode; local base64_decode = require "util.encodings".base64.decode; +local secure_equals = require "util.hashes".equals; local b64url_rep = { ["+"] = "-", ["/"] = "_", ["="] = "", ["-"] = "+", ["_"] = "/" }; local function b64url(data) @@ -33,7 +34,7 @@ elseif header.alg ~= "HS256" then return nil, "unsupported-algorithm"; end - if b64url(hashes.hmac_sha256(key, signed)) ~= signature then + if not secure_equals(b64url(hashes.hmac_sha256(key, signed)), signature) then return false, "signature-mismatch"; end local payload, err = json.decode(unb64url(bpayload));