Textmode for dummies (me)

Werner Koch wk at gnupg.org
Wed Jan 11 12:48:44 CET 2006

On Tue, 10 Jan 2006 22:39:00 -0700, Kurt Fitzner said:

> the only time GnuPG writes an input file to its output as text.  So, I
> did the following on a Linux box:
>   $ gpg --clearsign --textmode test1.txt

--clearsign automatically enables --textmode.

The rationale for the plain textmode (binary or armored messages) is
to allow the recipient to unpack the data with his native line
encodings.  To support this the line encodings are canonicalized (to
CR,LF) when hashing the document.  Thus the signature will can be
verified even when the line encodings has been changed.

> So, if --textmode doesn't convert to CRLF during clearsigning, when does
> it convert?

It does not convert the data you see but does it only internally
during signature creation/verification.

> Also, I noticed when searching for information, some sample command
> lines given with --textmode and --detach-sign.  What is the purpose of
> textmode for a detached signature?  The man page further explains

Same as above.  The signature is calculated over teh canonicalized document.

> --textmode sets a text flag in the message.  Does a detached signature
> have this text flag?  Is any sort of conversion done on the original


> file during verification of a detached signature?

No (only internally).



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