file extension confusion: --clearsign makes binary .asc

Hans-Christoph Steiner hans at guardianproject.info
Thu Jul 25 18:32:23 CEST 2013 

On 07/25/2013 11:15 AM, Werner Koch wrote:
> On Thu, 25 Jul 2013 17:05, hans at guardianproject.info said:
> 
>> Right, so when you do --clearsign without --armor on a binary file, the
> 
> Clearsign always enables the armor option.  The sole purpose of
> clearsign is to send human readable (aka plain ascii) text using a
> simple ascii encapsulation.  If you don't feed it with ascii (or utf-8)
> you still get the clearsign format.  Actually it is not even possible to
> use clearsign for non-ascii because the specs demand certain
> conversation which are not reversible (line ending, trailing whitespace,
> ^From).

So are you saying that OpenPGP's spec for --clearsign does not allow for
base64-encoded binary data?  If so, I think that running "gpg --clearsign" on
a binary file should give a warning that its not a supported format.

I just tried --clearsign with a PNG on my Linux Mint/Maya machine, and both
gpg 1.4.11 and gpg2 2.0.17.  In both cases, the resulting file was not ASCII,
but the format I described: binary data and ASCII signature.  I attached the
PNG and the resulting file.

$ gpg --clearsign icon.png

You need a passphrase to unlock the secret key for
user: "Hans-Christoph Steiner <hans at at.or.at>"
4096-bit RSA key, ID 374BBE81, created 2009-06-20

$ less icon.png.asc
"icon.png.asc" may be a binary file.  See it anyway?
$ gpg --version
gpg (GnuPG) 1.4.11
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Home: ~/.gnupg
Supported algorithms:
Pubkey: RSA, RSA-E, RSA-S, ELG-E, DSA
Cipher: 3DES, CAST5, BLOWFISH, AES, AES192, AES256, TWOFISH, CAMELLIA128,
        CAMELLIA192, CAMELLIA256
Hash: MD5, SHA1, RIPEMD160, SHA256, SHA384, SHA512, SHA224
Compression: Uncompressed, ZIP, ZLIB, BZIP2
$ rm icon.png.asc
$ gpg2 --clearsign icon.png

You need a passphrase to unlock the secret key for
user: "Hans-Christoph Steiner <hans at at.or.at>"
4096-bit RSA key, ID 374BBE81, created 2009-06-20

$ less icon.png.asc
"icon.png.asc" may be a binary file.  See it anyway?
$ gpg2 --version
gpg (GnuPG) 2.0.17
libgcrypt 1.5.0
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Home: ~/.gnupg
Supported algorithms:
Pubkey: RSA, ELG, DSA
Cipher: 3DES, CAST5, BLOWFISH, AES, AES192, AES256, TWOFISH, CAMELLIA128,
        CAMELLIA192, CAMELLIA256
Hash: MD5, SHA1, RIPEMD160, SHA256, SHA384, SHA512, SHA224
Compression: Uncompressed, ZIP, ZLIB, BZIP2



-- 
PGP fingerprint: 5E61 C878 0F86 295C E17D  8677 9F0F E587 374B BE81
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A non-text attachment was scrubbed...
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Size: 9413 bytes
Desc: not available
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