Using Academic Signature under TAILS:

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Motivation:
Presently the "Highest End Security" against US and other government agencies may be using Academic Signature for document enciphering and exchange under TAILS .(Please excuse my hubris, but this is what I believe.) Using TAILS is somewhat inconvenient, so you may want to use this only if you suspect you are specifically and personally targeted by any of these organizations.
As we know today this doesn't only happen to the bad guys but unfortunately also to very honorable people.
Apparently nowadays it doesn't take more than to google for TAILS or TOR just once to be labeled as extremist by the US administration. From there it might be a very short step to being labeled as terrorist.

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Because once and again TAILS comes with broken dependencies,  I compiled a version of academic signature which works on TAILS 3.0.1. You can find it  here:
academic_signature4TAILS,   my GnuPG
-signature of the archive, my ECDSA-signature and my ECC-timestamp.
Just unzip to a folder in your persistent storage, mark the binary as executable and use this local copy.

If your
TAILS suffers from broken dependencies , you may alternatively try to fix these by going to a terminal and entering:

sudo apt-get clean;
sudo apt-get update;
sudo dpkg --configure -a;
sudo apt-get install -f;

Chances are, you'll be able then to install "g++", "libgtk3.0" and "make" and then compile from source for yourself.
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How To:
Since TAILS is based on a Debian and I develop Academic Signature on a recent Ubuntu(based on a recent Debian), my published binaries might not run on TAILS because some libraries might not match.
You will have to compile Academic Signature yourself in a persistent folder in this case under TAILS(or use the dedicated binaries linked above).
(Thanks Dirk for pointing out some issues, I tried to address them and included some of your comments below.)

0) Preparations
a) Set a root password on booting TAILS.
b) Make sure to have a persistent folder on your TAILS.
c) Download the Academic Signature source archive(or the alternate source) and my GnuPG signature to the persistent folder.
d) Verify my GnuPG Signature of the Academic Signature source.(GnuPG is included in TAILS).
    You can find my public OpenPGP-key here: https://www.fh-wedel.de/%7Ean/crypto/academic_signature_key.html
    or on the MIT Keyserver
e) Unzip the source archive.
f)  Run "sudo apt-get update" in a terminal.
       
now either
g) In Synaptic (Applications, System Tools, Administration), select the following three packages: make, g++ and libwxgtk3.0-dev. A number of additional dependencies will be taken care of automatically. This will take up about 75Mb. of additional disk space.
This step has to be redone, if you want to build aca_sig again in a new TAILS session.

or else
g) in a terminal type:
            sudo apt-get install g++;
            sudo apt-get install wxgtk3.0;
            sudo apt-get install make;


now either
:
3 a) (for the tarball) Change to Aca-sig's download directory and call as usual "./configure" then "make".
Upon successful building, you use the local binary. Installation to the system via "sudo make install" should be omitted since it would only install for this session and would not persist in TAILS - just work with the local copy of the binary and the local helper subdirectories "x_secrets" and "key_tray" in the persistent folder.


or:
3 option b)
(for the alternate source) Change to Aca-sig's download directory and directly call the hand-made makefile "make release".
Upon successful building, you should use the local binary. Installation to the system via "sudo make install" should be omitted since it would only install for this session and would not persist in TAILS - just work with the local copy of the binary and the local helper subdirectories "x_secrets" and "key_tray" in the aca_sig directory in the persistent folder.
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Both methods work for me with the current TAILS 1.6(up to TAILS 3.0.1 by now) without problems.

You may want to get some practice with TAILS (and Academic Signature, TOR, GnuPG,...) even if you are not specifically targeted. This would be a useful exercise to be prepared for the worst......
As I read in a discussion forum: The Gulags and KZs of the 20th century were full of innocent people who had "nothing to hide".

May honesty, openness, tolerance and democracy prevail,
        we don't need Orwellian thought control by administrations that tortured,
        let known torturers run around on the loose
        and tell the world about "values".

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