Question regarding Zipping / DES encryption

johnnykilo

Hi, I was wondering if anyone knew about DES encryption?

Specifically i have a text file that's 1.5mb, when i encrypt it with DES it's still 1.5mb, however if i Zip both the normal and the encrypted file, the zipped encrypted file ends up being about 10 times larger than the zipped normal file. Can anyone tell me why this is? When i view the encypted DES file it seems to be full of chinese characters, is it something to do with this?

Thanks.

FSL

If you think about it it's obvious.

Put simply, encryption is replacing every byte in the file with a different one according to a given algorithm and key; compression is replacing strings of the same character with a smaller string which indicates a replacement, the character and the number of times it occurs.

Unless the encryption was very basic, which DES is not, the occurrence of strings of the same character will be less likely in the encrypted file than the unencrypted one.

johnnykilo

Yeah i guess it is obvious if you think about . Thanks for your help anyway