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diff --git a/Assignment 3/Readme.md b/Assignment 3/Readme.md new file mode 100644 index 0000000..c7ac538 --- /dev/null +++ b/Assignment 3/Readme.md @@ -0,0 +1,103 @@ +# Breaking DES with Python +Solutions to the third homework assignment for the NWI-IBC023 Cryptography course, spring 2015, Radboud University Nijmegen. + +See the LICENSE file for the license & copyright information. + +## Dependencies +Python 2.7.6 (other versions may work) with libraries: Crypto, sys, getopt, os.path, binascii, random, time + +## Files + +### des-demo.py (exercise i) +Encrypt or decrypt a specified message using a specified key with DES. See `des-demo.py -h` for usage. + +### des-test.sh +Test des-demo.py using the test vectors from the assignment. + +### nthkey.py (exercise ii) +Demonstration of the working of the `nthKey(n)` method. No command line parameters, edit the number on the last line for another `n`. + +### 2des-demo.py (exercise iii) +2DES using two random keys: chooses two random keys with the right parity using `nthKey(n)`, then performs 2DES on ten random plaintexts using those keys. See `2des-demo.py -h` for usage. + +### break.py (exercise iv) +Breaking 2DES using a known-plaintext attack. Supply at least a plaintext (`-p`) and a ciphertext (`-c`), possibly also a keylength (`-l`). There is an option to save the dictionary to a file (`-s`) if you're planning to reuse it. + +There is detailed timing information for the second stage of the attack: the time used by `nthKey()`, `DES.decrypt()` and finding values in the dictionary. + +Example: + + $ ./break.py -p 6be6065663da8d2c -c 4d0ed7812caeee83 -l 16 + Making dictionary (p:6be6065663da8d2c;l:16)... 1.429026s + Finding matches... 1.618808s + Key generation: 0.403714s + Decryption: 1.048049s + Matching dictionary: 0.046321s + k1: 0101010101011afb; k2: 0101010101012073 + +## Concrete break +I was given the following plaintext-ciphertext pairs: + + 0123456789ABCDEF e0ac28c346fb8de5 + 1122334455667788 49e4857e94f9655d + 99aabbccddeeff00 b5a2eefb51b04401 + +Breaking these (on the Lenovo described under Benchmarks): + + $ ./break.py -p 0123456789ABCDEF -c e0ac28c346fb8de5 -l 24 + Making dictionary (p:0123456789abcdef;l:24)... 417.513822s + Finding matches... 419.125502s + Key generation: 102.954099s + Decryption: 269.473773s + Matching dictionary: 15.134741s + k1: 0101010101164613; k2: 0101010102a719c2 + $ ./break.py -p 1122334455667788 -c 49e4857e94f9655d -l 24 + Making dictionary (p:1122334455667788;l:24)... 386.554364s + Finding matches... 424.907323s + Key generation: 106.151418s + Decryption: 271.449573s + Matching dictionary: 15.2167599999s + k1: 0101010101164613; k2: 0101010102a719c2 + $ ./break.py -p 99aabbccddeeff00 -c b5a2eefb51b04401 -l 24 + Making dictionary (p:99aabbccddeeff00;l:24)... 394.505993s + Finding matches... 431.637707s + Key generation: 109.764972s + Decryption: 274.681545s + Matching dictionary: 14.4759990001s + k1: 0101010101164613; k2: 0101010102a719c2 + +We find k1 = `0101010101164613`; k2 = `0101010102a719c2`. + +## Benchmarks + +### Lenovo U410, i7-3517U @ 1.9GHz, 8GB RAM, 16GB /swap, Ubuntu 14.04 +Creating dictionary: 417.5s, 386.5s, 394.5s (**avg: 399.5s**) +Finding matches: 419.1s, 424.9s, 431.6s (**avg: 425.2s**) + +The exact log is in the Concrete Break section above. + +### Lilo +Creating dictionary: 286.8s, 283.6s, 273.0s (**avg: 281.1s**) +Finding matches: 301.6s, 285.6s, 292.2s (**avg: 293.1s**) + + $ ./break.py -p 0123456789ABCDEF -c e0ac28c346fb8de5 -l 24 + Making dictionary (p:0123456789abcdef;l:24)... 286.83s + Finding matches... 301.56s + Key generation: 64.47s + Decryption: 200.23s + Matching dictionary: 9.27s + k1: 0101010101164613; k2: 0101010102a719c2 + $ ./break.py -p 1122334455667788 -c 49e4857e94f9655d -l 24 + Making dictionary (p:1122334455667788;l:24)... 283.55s + Finding matches... 285.63s + Key generation: 60.66s + Decryption: 189.44s + Matching dictionary: 9.27s + k1: 0101010101164613; k2: 0101010102a719c2 + $ ./break.py -p 99aabbccddeeff00 -c b5a2eefb51b04401 -l 24 + Making dictionary (p:99aabbccddeeff00;l:24)... 272.96s + Finding matches... 292.21s + Key generation: 63.89s + Decryption: 191.04s + Matching dictionary: 9.41s + k1: 0101010101164613; k2: 0101010102a719c2
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