https://github.com/stef/gpk
automatically generate pgp keys
https://github.com/stef/gpk
Last synced: about 1 year ago
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automatically generate pgp keys
- Host: GitHub
- URL: https://github.com/stef/gpk
- Owner: stef
- Created: 2012-09-28T23:21:41.000Z (over 13 years ago)
- Default Branch: master
- Last Pushed: 2014-01-15T23:44:28.000Z (over 12 years ago)
- Last Synced: 2025-03-29T03:11:15.504Z (over 1 year ago)
- Language: Shell
- Size: 146 KB
- Stars: 10
- Watchers: 3
- Forks: 4
- Open Issues: 1
-
Metadata Files:
- Readme: README.genkeyid.org
Awesome Lists containing this project
README
* genkeyid
A tool that helps you bruteforce arbitrary PGP keyids by modifying the
timestamp field so that the packet hashes to a given keyid.
Since this is a bruteforce attack on the hash algorithm to produce a
certain pattern in the hash we can increase our chances when we look
for multiple patterns. If the goal is not one specific keyid, but the
goal is to generate one of many keyids, then you can prepare a list of
multiple variations that would be acceptable, which increases your
chances considerably to find a good keyid with a plausible date.
* genkeyid.py
genkeyid.py takes a file containing a single public key and starts to
emit all possible keyids by incrementing the Public Key Creation Time
32bit integer from 0 upwards, recalculating the resulting hash. You
then have to filter this list of keyids, is it is a lot of data.
A basic invocation of genkeyid would look like this:
#+BEGIN_SRC sh
python ./genkeyid.py keyring.pub 2>snapshots | grep --color -i -f keycandidates | tee fps
#+END_SRC
Where keyring.pub is either a keyring with only one public key, or
your exported public key. The regular expressions per line in
keycandidates serve as filters (see example later), as genkeyid prints
out all possible keyids, and that is rather a lot of data, so you only
store your "hits" in the file "fps".
genkeyid emits snapshot ids to standard error, so you can always
resume it from some intermediate position by supplying the 32 bit
integer as the second parameter after the public key in genkeyid.py
runs to resume or skip processing (see an example in genid.sh).
* setfp.py
When this exhaustive bruteforce is finished after a few hours on a 3
year old laptop, you will have a list with potential keyids with
various dates that complement the hash to the specific keyid. You
choose the integer from row two and use setfp.py to patch your key
like this:
#+BEGIN_SRC sh
python ./setfp.py "
#+END_SRC
Be aware that patching the keys only works with unencrypted private
keys, so you should probably do this 2nd patching step only on a clean
offline system, that you afterwards shred, if you care about good key
hygene.
* genid.sh
There's also genid.sh which tries to automatically generate a new key
matching a given keyid. There's a few optimisations that burn much
more entropy but generate quite recent keys:
#+BEGIN_SRC sh
ksh -x ./genid.sh test "^DEADBEEF "
#+END_SRC
notice the format of the regex, it is anchored at the start of the
line, and depends on matching up to the first space, as the format
that genkeyid produces and which is grepped looks like this:
#+BEGIN_SRC sh
690f3700 1357248344 50 e5 f7 58 2013-01-03 22:25:44
#+END_SRC
Of course you could as mentioned earlier also look for more keyids
with more complex regular expressions.
So when you're done, you could do (presuming you have the binary
pgpdump installed):
#+BEGIN_EXAMPLE
diff -urw <(pgpdump test/pubring.pgp) <(pgpdump test/pubring.pgp-new)
--- /proc/self/fd/11 2013-04-04 00:36:23.307190845 +0200
+++ /proc/self/fd/12 2013-04-04 00:36:23.307190845 +0200
@@ -1,6 +1,6 @@
Old: Public Key Packet(tag 6)(141 bytes)
Ver 4 - new
- Public key creation time - Thu Apr 4 00:32:22 CEST 2013
+ Public key creation time - Fri Jan 4 15:06:30 CET 2013
Pub alg - RSA Encrypt or Sign(pub 1)
RSA n(1024 bits) - ...
RSA e(17 bits) - ...
@@ -36,7 +36,7 @@
Hashed Sub: key server preferences(sub 23)(1 bytes)
Flag - No-modify
Sub: issuer key ID(sub 16)(8 bytes)
- Key ID - 0xD39531EF87CB6015
- Hash left 2 bytes - a2 5b
- RSA m^d mod n(1022 bits) - ...
+ Key ID - 0xEDB069BE93FB0000
+ Hash left 2 bytes - 7c b8
+ RSA m^d mod n(1024 bits) - ...
-> PKCS-1
#+END_EXAMPLE