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pythonalgorithmcryptographypycryptodes
Gülşah Demiryürek
Gülşah Demiryürek

Reputation: 1

DES Algorithm with Python Crypto.Cipher Key -8 bits

I'm trying to encrypt a string variable to understand DES Algorithm with Python Crypto.Chiper package. But I don't really understand why key length must be 8 bytes long. I searched everywhere and I saw DES algorithm key length is 56 bits. Why are they different?

Upvotes: 0

Views: 461

Answers (1)

user4668606
user4668606

Reputation:

As described e.g. on wikipedia, the key consists of 56bit + 8 parity bits. Since these usually aren't used in the encryption-process itself, they usually don't get mentioned (see e.g. here for details). In fact the DES implementation in Crypto.Cipher explicitly states that parity-bits are discarded. So basically it's a relic of the olden days of crypto and a design-decision of the creators of the library.

Upvotes: 1

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