TAB at EOL (GPG and PGP interoperability)
Fri Jan 10 18:27:02 2003

>Message: 5
>Date: Thu, 9 Jan 2003 18:44:41 -0500
>From: David Shaw <>
>Subject: Re: TAB at EOL (GPG and PGP interoperability)

>> and then, after pgp 'wrapping'(or e-mail wrapping), the character at
>> the end of the line, got transferred to the beginning of the next
>> line, leaving a TAB to end the line, but not as intentional trailing
>> space
>This is not what happened. If you modify GnuPG to have the same bug,
>the file verifies properly.
>In any event, it doesn't matter how it got that way. If the line ends
>on a tab, the tab must be ignored. Period. 

you're right.

neither pgp nor gnupg will wrap a line ending in a tab followed by a character, and leave an empty tab space,

but interestingly, they do treat 'tab's differently:

assuming that gnupg wraps a clearsigned message at 64 characters,
and pgp at 76 characters

consider a plaintext of the following 3 lines:

abcdefghi1abcdefghi2 ... abcdefghi9

a'TAB''TAB' ... 'TAB'b'TAB'c

the first line has 90 characters, and is meant as a reference line.

the second line is empty, to allow to see what is 'wrapped' from the clearsigning.

the third line is the 'test' line:
one character at the beginning, then tabs until position 81, with a character at position 81, then one more tab, and a character at position 89

when clearsigned by gnupg, the first line wraps as expected, with all the characters after the 64th, moved to the next line.
but the test line does not wrap at all, instead the tabs are 'compressed' and the three 'real' characters stay on the same line,
with the last character at the 47th position.

when clearsigned by pgp, again, the first line wraps, this time after the 76th character,
but the test line is *unchanged* 
no wrap, no compression, and is allowed to remain at the 89th position.

either way,
both gnupg and pgp each verify the clearsigned messages of the other,

which leaves a puzzling question:
why would the files Knut was referring to have a 'tab' at the end of a line?

{sorry for having mis-spelled the name in a previous post,
have been holding off on getting the 'glasses with the lines in them'
have since increased the text size in the reader ;^)   }

with Respect,



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