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cipher/ decipher with 3DES alg

Algorithm School

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Ruenie
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cipher/ decipher with 3DES alg

Post by Ruenie » Wed Apr 26, 2017 11:46 pm

Hey guys,

I came across a problem recently. Hope you can figure me out.

I tried to cipher some text with 3DES alg with a key of 16 bytes. And I asked users to input the first part of my 16 bytes key - that is 8 characters. The second part is hard-coded.

I tried with simple key like "12345678". It ciphers without any problem. So I expected that the result could only be deciphered with that key. But the fact proved that what I thought was wrong. I can also decipher with a similar key, like "12345679".

Can anyone figure out the reason why this happened?

Thank you so much.

chico0609
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Re: cipher/ decipher with 3DES alg

Post by chico0609 » Thu Apr 27, 2017 4:17 am

It seems that your problem has something to do with DES weak key. Do you use weak key?

Ruenie
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Re: cipher/ decipher with 3DES alg

Post by Ruenie » Thu Apr 27, 2017 6:01 am

I didn't use any weak key. Except 3DES, can I use other algorithms?

chico0609
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Re: cipher/ decipher with 3DES alg

Post by chico0609 » Fri Apr 28, 2017 4:23 am

Try to use AES instead.

tay00000
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Re: cipher/ decipher with 3DES alg

Post by tay00000 » Fri Apr 28, 2017 6:17 am

Provide sample code so that accurate advice on the problem with your 3DES implementation can be given. With only your brief description, nobody is able to properly visualize the problem.

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