BUBlic's ElGamal keygenme #1
| Download ElGamal_keygenme_1_by_BUBlic.zip, 132 kb (password: crackmes.de) Browse contents of ElGamal_keygenme_1_by_BUBlic.zip Do you find RSA boring while you still can't get ECC?
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Solutions
Solution by HMX0101, published 21. oct, 2008; download (30 kb), password: crackmes.de or browse.
HMX0101 has not rated this crackme yet.
Discussion and comments
| m@rio_crk 12. Apr 2006 | uff at least! ;) You made me confused there for a lil' bit, (you cannot make serial for every name in this crackme) Anyway.. you made really nice work with this kgnme. Cheers :) |
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| pdrill 17. Apr 2006 | Elgamal??, CRC cant be greater that p-1. (is this a bug?). Only first time will the change base function work when it's init with 6. (is this also a bug?) |
| jB_ 18. Apr 2006 | Strange implementation of ElGamal encryption. ElGamal security relies on discrete logarithm problem. In your implementation you don't have to compute it. It is a pity... I guess the "Change base" function is really bugged, I don't see why this could be coded on purpose. pDrill : CRC "can't" or "can" be greater than p-1? It is shifted, so it is 24 bit max, this is ok. |
| BUBlic Author 18. Apr 2006 | Hi guys, I'm sorry for that one. It was my very first attempt to code a keygenme base on the DLP, but as I've seen now it doesn't. Maybe its still good to learn a bit about modular arithmetics (especially d=ab^c mod p). Indeed the last days I learnd a lot, and a better one *promised* will follow. |
| pdrill 19. Apr 2006 | Hi, I hop I dont spoil any thing by posting this but the only thing you have to do is to compute "serial = crc * 91C7C9 mod E476A3" and convert to your input type. (91C7C9 = 638297^-1 mod E476A3). If CRC gets greater than p-1 you cant make a key for that name. And for some names the CRC will get greater. Like "Name: Stanley". (You should always reduce it mod p to avoid this.) |
| jB_ 19. Apr 2006 | Oups pDriLl you're right with the CRC. And your solution is ok. BUBlic I wait for the next one. Take your time =) |
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