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SigWrite *Alpha*


Download

sigwrite-1.2.0.zip (111K) a zipped hfs disk image and checksum file. The disk image can be mounted with Mini vMac. Includes source code.

SigWrite is a tool for creating digital signatures that can be checked with the SigCheck tool. It is intended to eventually replace PSgWrite, a similar tool that uses an incompatible format. (Almost all the digital signatures found throughout this website are still in that format.)

Screenshot

To use SigWrite, launch the application, and in the editing window that appears, paste in a message to be signed. For example:

Twas brillig, and the slithy toves
did gyre and gimble in the wabe:
All mimsy were the borogoves,
and the mome raths outgrabe.

Copy all of the indented text above. Then paste it into SigWrite, which requires getting the clipboard into the emulated Macintosh, if SigWrite is run inside Mini vMac. You can get text into the emulated Macintosh using the “Host Paste” command in the Edit Menu of SigWrite. It is like the “Paste” command, except that it uses the clipboard of the real computer instead of the clipboard of the emulated computer. The keyboard shortcut is Command-Option-V. (The “Host Paste” command has similar effect to using ClipIn and then the normal “Paste” command.)

Then click on the status bar, at the bottom of the window below the editing area. (Choosing the ‘Go’ command from the File menu, of the emulated Macintosh, will also work. The keyboard shortcut is Command-G.)

The editing area is cleared. Next paste in a secret key to sign the message with. (One can be created with MakeKeys). For example (and only as example, normally a secret key should never be given to anyone else):

----- BEGIN GRY SECRET KEY -----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------ END GRY SECRET KEY ------

Before continuing, it would be a good idea to set Mini vMac to All Out speed. Then, on a modern computer, SigWrite should take less than ten seconds to run (for a 1024 bit key, as in this example). At 1x speed, or on a real Macintosh Plus, it takes much longer. The code of SigWrite is intended to be simple to understand and maintain, as opposed to fast.

Again, click on the status bar. After a while, if all is well, the edit area is replaced with the signed text:

--------- GRY SIGNED TEXT ---------

Twas brillig, and the slithy toves
did gyre and gimble in the wabe:
All mimsy were the borogoves,
and the mome raths outgrabe.

------- BEGIN GRY SIGNATURE -------
Gry/AXuKqWsF8Rh5/Bb045yIowANlvp/V/ymKoDa55Wb7dW/xGfPmca8oLw+Rv9d
cSQpcL+XpzESnWqpK/uNg7lTIe4wdOzo1/s6bHU0u27J+A5EngkYQiAMHeETq6Nx
DM8viQbkNx2UZrDxyOLCGXW1N4txMktyjC3DYzRMH/oKBVHxgP6B2j8sipEgp3Zf
-------- END GRY SIGNATURE --------

When SigWrite is run inside Mini vMac, you can get text out of the emulated Macintosh using the “Host Copy” command in the Edit Menu. It is like the “Copy” command, except that it uses the clipboard of the real computer instead of the clipboard of the emulated computer. The keyboard shortcut is Command-Option-C. (The “Host Copy” command has similar effect to using the normal “Copy” command and then ClipOut.)

SigWrite is in part descended from MacPGP source code, which, as far as I can tell, allows derived works for noncommercial use.

MacPGP has various code to try to protect secrets from other software running on the computer. SigWrite does not, instead you should try to secure the entire virtual machine that it is run in. Such as by putting the Mini vMac disk image on an encrypted volume of the host computer, for a start.

Here is the md5 checksum for the download, signed with Gryphel Key 1:

-----BEGIN PGP SIGNED MESSAGE-----

88431b1a988637870f706027db02cbf4 sigwrite-1.2.0.zip

-----BEGIN PGP SIGNATURE-----
Version: 2.6.3ia
Charset: noconv

iQCVAwUBWq5g6Niugru7WJg5AQGUtgP7BJwzw4YyFZu6VpD/tcwcUpFuS5faRPw7
nOc7HA0J2ZA2IGzXpx1lfF9OuedxoHOGaMgddxdohz8f5YMVurdewXl9CSz4Km3J
2CBFHi4VAGaxENjK6U6vbELirGnLMIP2eL0MbglEb5eWUTfNIYgV+xXWyfSN3o5L
eQF9AmOMrTo=
=KTge
-----END PGP SIGNATURE-----

See the Compiling page for instructions on compiling SigWrite from the source code.

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If you find SigWrite useful, please consider helping the Gryphel Project, of which it is a part.

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copyright (c) 2018 C. Pratt - last update 3/18/2018