From: arrtchiu@...
Date: 2014-08-23T09:12:53+00:00
Subject: [ruby-core:64508] [ruby-trunk - Feature #10098] [PATCH] Timing-safe string comparison for OpenSSL::HMAC

Issue #10098 has been updated by Matt U.

File 0001-add-timing-safe-string-compare-method.patch added

Changelog:

* Renamed `rb_tsafe_eql` => `rb_consttime_memequal`.
* Renamed `rb_str_tsafe_eql` => `rb_str_consttime_bytes_eq`.
* Renamed `tsafe_eql?` => `consttime_bytes_eq?`.
* `rb_consttime_memequal` now has return type `int`.
* Updated documentation to reflect that encodings are ignored, and removed reference to `eql?`.
* Added tests to ensure timing safety (delta of 0.25 sec allowed to account for GC/system noise).
* Build on Travis passing: https://travis-ci.org/ruby/ruby/builds/33351019

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Feature #10098: [PATCH] Timing-safe string comparison for OpenSSL::HMAC
https://bugs.ruby-lang.org/issues/10098#change-48453

* Author: Matt U
* Status: Open
* Priority: Normal
* Assignee: 
* Category: ext/openssl
* Target version: next minor
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I could be totally wrong, but it seems the standard library doesn't provide a reliable way of comparing hashes in constant-time.

* The docs for `OpenSSL::HMAC` encourage the use of `Digest#to_s` (see: http://ruby-doc.org/stdlib-2.1.0/libdoc/openssl/rdoc/OpenSSL/HMAC.html#method-c-new )
* Ruby's string comparison uses memcmp, which isn't timing safe (see: http://rxr.whitequark.org/mri/source/string.c#2382 )

With this patch I propose to add an additional method, `OpenSSL::HMAC#verify`, which takes a binary string with a digest and compares it against the computed hash.


---Files--------------------------------
hmac-timing.patch (2.5 KB)
hmac-timing.patch (2.48 KB)
tsafe_eql.patch (2.48 KB)
tsafe_inline.patch (3.51 KB)
0001-add-timing-safe-string-compare-method.patch (4.31 KB)


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