Challenge : apply these methods to crack simple codes

Question

Many texts are crypted using simple methods like https://www.sololearn.com/Discuss/981018/?ref=app

Make a program that runs the following attacks on a crypted text

1- Use letters frequency to try to "recognize" letters (see hereunder frequencies for the 1st letter of english words and all the letters)
2- Display the first tens of characters of the text using all the caesar possibilities
3- XOR each ascii code with a constant value for different values of XOR masks giving enough letters or digits as % of the total size of the text
4-any other additionnal method

firstchar=[0.11682,0.04434,0.05238,0.03174,0.02799,0.04027,0.01642,0.042,0.07294,0.00511,0.00456,0.02415,0.03826,0.02284,0.07631,0.04319,0.00222,0.02826,0.06686,0.15978,0.01183,0.00824,0.05497,0.00045,0.00763,0.00045]
allchar=[0.08167,0.01492,0.02782,0.04253,0.12702,0.02228,0.02015,0.06094,0.06966,0.00153,0.00772,0.04025,0.02406,0.06749,0.07507,0.01929,0.00095,0.05987,0.06327,0.09056,0.02758,0.00978,0.0236,0.0015,0.01974,0.00074]

Answer 1

Another great challenge again! Serious I think VcC your skill in algorithm is far better than most of us here, including me. 👍😉

Answer 2

@zephyr Stop flattering, start coding ;-) !

Answer 3

bugs fixed
it will give you several clear possibilities.

https://code.sololearn.com/cUQA58NCL1Mq/?ref=app

Answer 4

This one does #2, ie brute force on a Caesar cipher:

https://code.sololearn.com/cB6quUzeSLtV

Answer 5

https://code.sololearn.com/c7qc0rOjP2eW/?ref=app

Answer 6

Can explain what you mean by #3?
Is that a try all 255 bytes combinations? ie Bute force.

Answer 7

@jared : yes for example. but you might consider other methods. Xor is proposed because it is sometimes used in simplist cryptos.

Alternatively you can limit to the case when xor gives readable characters (31-127 ascii) and has enough letters+digits as a % of total characters...

Answer 8

examples. look at the xor method
https://code.sololearn.com/cgZm0YxU3mov/?ref=app

Answer 9

Here is a code to crack a code using text statistics. relaunch if the result is bad
Feel free to clean and improve (there could be better ways to use 2 3 4grams to guess the first code)