Comp

Comp, COMP or Comps may refer to:

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Strong Bad

Strong Bad is a fictional character from the Homestar Runner series of animated Flash web cartoons. He is portrayed by Matt Chapman, the principal voice actor and co-founder of the series. Strong Bad enjoys pranking the other characters of the series, along with his ever-diligent lackey pet named "The Cheat" and his older brother Strong Mad. The main segment that Strong Bad is a part of is "Strong Bad Email", in which he answers emails sent to him by fans. The Strong Bad Email series grew to be so popular that seven DVDs featuring the emails have been released, as well as a podcast where emails could be downloaded to digital media players, since its first episode in 2001.

The character sports a red lucha libre mask with 4 laces in the back and a blue diamond in the center of his eyes. The diamond has the power to open bottle caps from "Cold Ones" and remove Homestar's hat, though he has only been seen doing this once. His eyes are green and shiny, and apparently turn grey when he is dead. Usually his mouth is a peach-colored rectangle when not speaking, and can form the shape of an "o" when using words with an "o" sound in them. He lacks a shirt (but wears certain ones on occasion), nipples, and a belly button. Strong Bad also has boxing gloves for hands, though mysteriously he can type with them in his Strong Bad Emails. He also wears black pants, along with red shoes with white soles that curve outward.

COMP128

The COMP128 algorithms are implementations of the A3 and A8 algorithms defined in the GSM standard. The A3 algorithm is used to authenticate the mobile station to the network. The A8 algorithm is used to generate the session key used by A5 to encrypt the data transmitted between the mobile station and the BTS.

Currently there exist four versions of COMP128. The first three were originally confidential. A partial description of the first version was leaked in 1997 and completed via reverse engineering. This led to a full publication in 1998. The second and third versions were obtained via reverse engineering of software which verifies SIM cards compliance.

Introduction

For details on the way A3 and A8 are used see Authentication Center.

A3 and A8 both take a 128-bit key (K_i) and a 128-bit challenge (RAND) as inputs. A3 produces a 32-bit response (SRES) and A8 produces a 64 bits session key (K_c).

The COMP128 algorithms combine the functionality of A3 and A8.

COMP128 algorithms

Several COMP128 algorithms were designed: