A set of Python tools useful for cryptography and cryptanalysis. More documentation will be added later.
You can install the dependencies with the following command:
pip install -r requirements.txt
library/ciphers holds the objects for ciphers. library/data holds the objects for data manipulation.
library/statistics holds the objects for statistical operations.
frequency_analysis.py will show the ngram frequency analysis of an input file.
$ python frequency_analysis.py samples/cipher1.txt
**** Cipher Text ****
tpfccdlfdtte pcaccplircdt dklpcfrp?qeiq lhpqlipqeodf gpwafopwprti izxndkiqpkii krirrifcapnc dxkdciqcafmd vkfpcadf.
Letter Counts:
p = 13
c = 12
i = 11
d = 10
f = 9
k = 6
r = 6
q = 6
l = 5
t = 5
a = 5
e = 3
o = 2
n = 2
w = 2
x = 2
m = 1
z = 1
v = 1
g = 1
h = 1
Digram Counts:
ca = 4
iq = 3
pq = 3
pc = 3
cd = 3
dt = 2
df = 2
ki = 2
...
lf = 1
Trigram Counts:
pqe = 2
pca = 2
qpk = 1
dci = 1
...
lfd = 1
Quadgram Counts:
rrif = 1
eodf = 1
cdtd = 1
...
rpqe = 1
monoalphabuster.py tries to crack the input cipher file assuming a mono alpha substitution cipher was used.
$ python monoalphabuster.py -h
usage: monoalphabuster.py [-h] [-s] [-p] [-m] CipherFile
Attempts to decrypt mono alpha ciphers.
positional arguments:
CipherFile The cipher file to decrypt.
optional arguments:
-h, --help show this help message and exit
-s, --spaces Counts spaces as a valid cipher character instead of
ignoring them.
-p, --punctuation Counts punctuation as valid cipher characters instead of
ignoring them.
-m, --mayzner Use Mayzner statistical data.
By default the data used for cracking came from practicalcryptography.com. You can try the Mayzner data, but the PC data tends to crack the cipher faster, in my experience.
$ cat samples/cipher1.txt
tpfccdlfdtte pcaccplircdt dklpcfrp?qeiq lhpqlipqeodf gpwafopwprti izxndkiqpkii krirrifcapnc dxkdciqcafmd vkfpcadf.
$ python monoalphabuster.py samples/cipher1.txt
Loading statistical data...
Cipher Text:
tpfccdlfdtte pcaccplircdt dklpcfrp?qeiq lhpqlipqeodf gpwafopwprti izxndkiqpkii krirrifcapnc dxkdciqcafmd vkfpcadf.
Looping continuously, press ctl-c when you have your plain text!
*****
Iteration 1 better score -486.74027673721775
Current Cipher Key/Plain Values:
['p', 'm', 'q', 'n', 'i', 'u', 'v', 'e', 'd', 'z', 'l', 't', 'o', 'k', 'a', 'h', 'y', 'f', 'r', 'c', 'x', 'j', 'g', 'b', 'w', 's']
['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']
Cipher Text:
tpfccdlfdtte pcaccplircdt dklpcfrp?qeiq lhpqlipqeodf gpwafopwprti izxndkiqpkii krirrifcapnc dxkdciqcafmd vkfpcadf.
Current Plain Text:
larttikrillh atottakestil inkatrsa?chec kpackeachmir wayormayasle ejudinecanee nsessertoadt iunitectorbi gnratoir.
*****
Iteration 2 better score -451.06928385640185
Current Cipher Key/Plain Values:
['p', 'j', 'o', 'r', 'i', 'x', 'm', 'e', 'a', 'y', 'l', 'w', 'n', 'f', 'd', 'z', 'u', 'k', 'q', 'c', 'v', 'g', 't', 's', 'h', 'b']
['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']
Cipher Text:
tpfccdlfdtte pcaccplircdt dklpcfrp?qeiq lhpqlipqeodf gpwafopwprti izxndkiqpkii krirrifcapnc dxkdciqcafmd vkfpcadf.
Current Plain Text:
wanttoknowwh atittakedtow orkatnda?shes kyaskeashcon valincaladwe epfmoresaree rdeddentiamt ofrotestingo urnation.
*****
Iteration 8 better score -432.5413722871861
Current Cipher Key/Plain Values:
['p', 'h', 'q', 'o', 'i', 'g', 'm', 'e', 'a', 'y', 'l', 'n', 'w', 'f', 'd', 'x', 'b', 'k', 'r', 'c', 'v', 'u', 't', 'z', 's', 'j']
['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']
Cipher Text:
tpfccdlfdtte pcaccplircdt dklpcfrp?qeiq lhpqlipqeodf gpwafopwprti izxndkiqpkii krirrifcapnc dxkdciqcafmd vkfpcadf.
Current Plain Text:
wanttoknowwh atittakestow orkatnsa?chec kbackeachdon famindamaswe explorecaree rsessentialt oprotectingo urnation.
*****
Iteration 243 better score -431.10849018770915
Current Cipher Key/Plain Values:
['p', 'h', 'q', 'g', 'i', 'y', 'm', 'e', 'a', 's', 'l', 'n', 'o', 'f', 'd', 'x', 'b', 'k', 'r', 'c', 'v', 'u', 't', 'z', 'w', 'j']
['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']
Cipher Text:
tpfccdlfdtte pcaccplircdt dklpcfrp?qeiq lhpqlipqeodf gpwafopwprti izxndkiqpkii krirrifcapnc dxkdciqcafmd vkfpcadf.
Current Plain Text:
wanttoknowwh atittakestow orkatnsa?chec kbackeachmon dayinmayaswe explorecaree rsessentialt oprotectingo urnation.
Some of the data for these tools were downloaded from http://norvig.com/mayzner.html. The License of that project applies to that data only. Some other data was downloaded from http://practicalcryptography.com/. The License of that project applies to that data only. The data can be found in the data directory.
Here are some references that were consulted for this project:
- http://practicalcryptography.com/cryptanalysis/text-characterisation/quadgrams/#a-python-implementation
- http://storage.googleapis.com/books/ngrams/books/datasetsv2.html
- Cryptography and Network Secuirty, William Stallings, 7th Edition
- http://vanilla47.com/PDFs/Cryptography/Cryptoanalysis/A%20Fast%20Method%20for%20Cryptoanalysis%20of%20Substitution%20Ciphers.pdf
- http://norvig.com/mayzner.html
- http://www.data-compression.com/english.html
- http://quipqiup.com/
- http://www.ti89.com/cryptotut/frequencies.htm
- http://altamatic.com/crypt
This application(s) is/are covered by the Creative Commons BY-SA license.