code review 6392050: xts: add package.

xts: add package.

Package xts implements the XTS cipher mode as specified in IEEE
P1619/D16.

[agl1, 2012-07-11 19:32:52]

Hello golang-dev@googlegroups.com (cc: golang-dev@googlegroups.com),

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

[r, 2012-07-11 21:20:21]

LGTM

http://codereview.appspot.com/6392050/diff/5001/xts/xts.go
File xts/xts.go (right):

http://codereview.appspot.com/6392050/diff/5001/xts/xts.go#newcode7
xts/xts.go:7: // XTS mode is typically used for disk encryption which presents a
number of
s/encryption/&,/

http://codereview.appspot.com/6392050/diff/5001/xts/xts.go#newcode57
xts/xts.go:57: // plaintext and ciphertext may be the same slice but should
otherwise not
s/p/P/
not sure what 'otherwise' adds here. just delete it.

http://codereview.appspot.com/6392050/diff/5001/xts/xts.go#newcode89
xts/xts.go:89: // plaintext and ciphertext may be the same slice but should
otherwise not
ditto and ditto.

http://codereview.appspot.com/6392050/diff/5001/xts/xts.go#newcode120
xts/xts.go:120: // mul2 multiplies tweak by 2 in GF(2**128) with an irreducable
polynomial of
irreducible.

[dchest, 2012-07-12 11:18:08]

LGTM

http://codereview.appspot.com/6392050/diff/5001/xts/xts.go
File xts/xts.go (right):

http://codereview.appspot.com/6392050/diff/5001/xts/xts.go#newcode58
xts/xts.go:58: // overlap. Sectors must be a multiple of 16 bytes and less than
2*24 bytes.
2²⁴

[agl1, 2012-07-12 15:24:30]

*** Submitted as
http://code.google.com/p/go/source/detail?r=d77655906ece&repo=crypto ***

xts: add package.

Package xts implements the XTS cipher mode as specified in IEEE
P1619/D16.

R=golang-dev, r, dchest
CC=golang-dev
http://codereview.appspot.com/6392050

http://codereview.appspot.com/6392050/diff/5001/xts/xts.go
File xts/xts.go (right):

http://codereview.appspot.com/6392050/diff/5001/xts/xts.go#newcode7
xts/xts.go:7: // XTS mode is typically used for disk encryption which presents a
number of
On 2012/07/11 21:20:21, r wrote:
> s/encryption/&,/

Done.

http://codereview.appspot.com/6392050/diff/5001/xts/xts.go#newcode57
xts/xts.go:57: // plaintext and ciphertext may be the same slice but should
otherwise not
On 2012/07/11 21:20:21, r wrote:
> s/p/P/
> not sure what 'otherwise' adds here. just delete it.

My thinking was that setting plaintext=ciphertext is a case of overlapping, but
otherwise overlapping isn't allowed.

But I guess that wasn't clear so I've removed otherwise.

http://codereview.appspot.com/6392050/diff/5001/xts/xts.go#newcode58
xts/xts.go:58: // overlap. Sectors must be a multiple of 16 bytes and less than
2*24 bytes.
On 2012/07/12 11:18:09, dchest wrote:
> 2²⁴

Thanks, done. (And I switched to using unicode superscript elsewhere in the
comments.)

http://codereview.appspot.com/6392050/diff/5001/xts/xts.go#newcode89
xts/xts.go:89: // plaintext and ciphertext may be the same slice but should
otherwise not
On 2012/07/11 21:20:21, r wrote:
> ditto and ditto.

Done.

http://codereview.appspot.com/6392050/diff/5001/xts/xts.go#newcode120
xts/xts.go:120: // mul2 multiplies tweak by 2 in GF(2**128) with an irreducable
polynomial of
On 2012/07/11 21:20:21, r wrote:
> irreducible.

Done.