Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I notice that services like Gmail use RC4 128 bit as encryption.

What is RC4 encryption and how does it work?
Is 128-bit RC4 considered strong encryption?

share|improve this question
1  
@alnik: but internet politics! :D –  Phoshi Apr 2 '10 at 12:55

1 Answer 1

description of RC4:

RC4 generates a pseudorandom stream of bits (a keystream) which, for encryption, is combined with the plaintext using bit-wise exclusive-or; decryption is performed the same way (since exclusive-or is a symmetric operation). (This is similar to the Vernam cipher except that generated pseudorandom bits, rather than a prepared stream, are used.) To generate the keystream, the cipher makes use of a secret internal state which consists of two parts: A permutation of all 256 possible bytes (denoted "S" below). Two 8-bit index-pointers (denoted "i" and "j").

The permutation is initialized with a variable length key, typically between 40 and 256 bits, using the key-scheduling algorithm (KSA). Once this has been completed, the stream of bits is generated using the pseudo-random generation algorithm (PRGA).

more on wiki

128-bit for this algorithm - recommended key length when the maximum is 256 bit.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.