GnuPG Summer Riddle 2007 [SOLUTION]

[Sascha Wilde]

Ingo Klöcker <kloecker at kde.org> wrote:
> On Friday 25 January 2008, Sascha Wilde wrote:
>> Ingo Klöcker <kloecker at kde.org> wrote:
>> > On Thursday 24 January 2008, Sascha Wilde wrote:
>> >> SPOILER WARNING - SPOILER WARNING - SPOILER WARNING - SPOILER
>> >>
>> >>                                 SOLUTION
>> >>
>> >> SPOILER WARNING - SPOILER WARNING - SPOILER WARNING - SPOILER

> For the fun of it I've written a generator for python apps printing an
> arbitrary string. All generated apps verify against the attached
> signature file. And as a plus each generated app is again a generator,
> i.e. the generator is self-replicating (albeit in the most simple way).

Sweet!  Sure enough I had to write a version in common lisp, which I
attached (including sig of cause).

New features/changes in the lisp implementation:

1. It's a real quine -- so it generates its source in stead of copying
   from the source-file.
2. Instead of printing a simple string the generated app can execute any
   arbitrary lisp form.  :-)

Ok, here is the usage example:

wilde at kenny% sbcl --noinform --no-userinit --load app-generator.lisp >app2.lisp
(dotimes (n 10) (format t "~a~%" n))
wilde at kenny% sbcl --noinform --no-userinit --load app2.lisp
0
1
2
3
4
5
6
7
8
9

And of cause one sig fits all:

wilde at kenny% gpg2 --verify app-generator.lisp.sig app-generator.lisp
gpg: Signature made Sat Jan 26 19:55:27 2008 CET using DSA key ID 69115024
gpg: Good signature from "Sascha Wilde <swilde at sha-bang.de>"
gpg:                 aka "Sascha Wilde <wilde at sha-bang.de>"
wilde at kenny% gpg2 --verify app-generator.lisp.sig app2.lisp
gpg: Signature made Sat Jan 26 19:55:27 2008 CET using DSA key ID 69115024
gpg: Good signature from "Sascha Wilde <swilde at sha-bang.de>"
gpg:                 aka "Sascha Wilde <wilde at sha-bang.de>"

And here are the files:

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cheers
sascha
--
Sascha Wilde
    "Computers are good at following instructions,
     but not at reading your mind."
    D. E. Knuth, The TeXbook, Addison-Wesley 1984, 1986, 1996, p. 9
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