Patent ID: 7796752
Filing Date: 2010-09-14
Classification: H04L

Abstract:
1. A method implemented in a mobile communication device, the method comprising: providing a key variable to a partial KASUMI block cipher, wherein said partial KASUMI block cipher implements only a fraction of all eight rounds of a full KASUMI block cipher and executes only a first round and a second round of said full KASUMI block cipher, and wherein an output of said partial KASUMI block cipher is not an output of a last round of said full KASUMI block cipher and is an output of said second round of said full KASUMI block cipher; using a first logic circuit to combine said output of said partial KASUMI block cipher with an output of a first register, wherein said first logic circuit does not compute one or more KASUMI rounds; wherein an output of said first logic circuit is coupled to an input of said partial KASUMI block cipher; generating a keystream block by using only one operation of said partial KASUMI block cipher, and without utilizing a full KASUMI block cipher, wherein generating said keystream block comprises: