Unnecessary padding about crypto-js

[GoogleCodeExporter]

I found the problem in padding function at calculating the number of bytes to 
add:
var nPaddingBytes = blockSizeBytes - data.sigBytes % blockSizeBytes;

To correct the problem with unnecessary padding when data.sigBytes = 
blockSizeBytes use this instead like in pad-zeropadding.js:
blockSizeBytes - ((data.sigBytes % blockSizeBytes) || blockSizeBytes);

The attached patch correct this in cipher-core.js. But the same problem exists 
also in pad-ansix923.js and pad-iso10126.js.

Original comment by [email protected] on 27 May 2014 at 11:15

Attachments:

• cipher-core_padding.patch

[GoogleCodeExporter]

Most padding schemes -- including PKCS7, ANSI.X, and ISO -- require that at 
least one bit or byte be added, always. 
(http://en.wikipedia.org/wiki/Padding_(cryptography)#Byte_padding) This is so 
that the message can later be un-padded correctly. Otherwise, it wouldn't 
always be possible to distinguish between the padding and the message.

Original comment by Jeff.Mott.OR on 27 May 2014 at 11:26

• Changed state: Invalid

[GoogleCodeExporter]

Thank you for the explanation!

Original comment by [email protected] on 28 May 2014 at 7:54