code review 62190043: crypto/subtle: panic if slices of different lengths are...

crypto/subtle: panic if slices of different lengths are passed to ConstantTimeCompare.

ConstantTimeCompare has always been documented to take equal length
slices but perhaps this is too subtle, even for 'subtle'.

Fixes issue 7304.

[agl1, 2014-02-12 16:23:30]

Hello golang-codereviews@googlegroups.com,

I'd like you to review this change to
https://code.google.com/p/go/

[hanwen-google, 2014-02-12 16:24:35]

On 2014/02/12 16:23:30, agl1 wrote:
> Hello mailto:golang-codereviews@googlegroups.com,
> 
> I'd like you to review this change to
> https://code.google.com/p/go/

LGTM

[bradfitz, 2014-02-12 16:25:54]

LGTM
 On Feb 12, 2014 8:23 AM, <agl@golang.org> wrote:

> Reviewers: golang-codereviews,
>
> Message:
> Hello golang-codereviews@googlegroups.com,
>
> I'd like you to review this change to
> https://code.google.com/p/go/
>
>
> Description:
> crypto/subtle: panic if slices of different lengths are passed to
> ConstantTimeCompare.
>
> ConstantTimeCompare has always been documented to take equal length
> slices but perhaps this is too subtle, even for 'subtle'.
>
> Fixes issue 7304.
>
> Please review this at https://codereview.appspot.com/62190043/
>
> Affected files (+4, -0 lines):
>   M src/pkg/crypto/subtle/constant_time.go
>
>
> Index: src/pkg/crypto/subtle/constant_time.go
> ===================================================================
> --- a/src/pkg/crypto/subtle/constant_time.go
> +++ b/src/pkg/crypto/subtle/constant_time.go
> @@ -10,6 +10,10 @@
>  // and y, have equal contents. The time taken is a function of the length
> of
>  // the slices and is independent of the contents.
>  func ConstantTimeCompare(x, y []byte) int {
> +       if len(x) != len(y) {
> +               panic("subtle: slices have different lengths")
> +       }
> +
>         var v byte
>
>         for i := 0; i < len(x); i++ {
>
>
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[agl1, 2014-02-12 16:59:21]

*** Submitted as https://code.google.com/p/go/source/detail?r=1e97bf2e0f93 ***

crypto/subtle: panic if slices of different lengths are passed to
ConstantTimeCompare.

ConstantTimeCompare has always been documented to take equal length
slices but perhaps this is too subtle, even for 'subtle'.

Fixes issue 7304.

LGTM=hanwen, bradfitz
R=golang-codereviews, hanwen, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/62190043