Method and apparatus for generating encryption stream ciphers
AssigneeQUALCOMM Incorporated
InventorGregory G. Rose
Life of this patent
Estimating the term…
Abstract
A method and an apparatus for generating encryption stream ciphers are based on a recurrence relation designed to operate over finite fields larger than GF(2). A non-linear output can be obtained by using one or a combination of non-linear processes to form an output function. The recurrence relation and the output function can be selected to have distinct pair distances such that, as the shift register is shifted, no identical pair of elements of the shift register are used twice in either the recurrence relation or the output function. Under these conditions, the recurrence relation and the output function also can be chosen to optimize cryptographic security or computational efficiency.
Claims20
A method of generating a stream cipher, comprising:
- selecting a finite field having an order greater than two;
- selecting a recurrence relation over said finite field;
- selecting a first non-linear function;
- selecting a second non-linear function;
- and
- computing said stream cipher in accordance with said recurrence relation, said first non-linear function, and said non-linear function, wherein said recurrence relation and said first non-linear function have distinct pair differences between said first non-linear function.
An apparatus for generating a stream cipher comprising:
- a processor for receiving instructions for performing a recurrence relation, a first non-linear function, and a second non-linear function, said processor performing manipulations on elements in accordance with said instructions, wherein said recurrence relation and said first non-linear function have distinct pair differences between recurrence relation and said first non-linear function.
A method for encrypting a stream data, comprising:
- generating an encryption bit stream by using a recurrence relation, using a first non-linear process upon the output of the recurrent relation and using a second non-linear process upon the output of the first non-linear process;
- and
- XORing the stream of data with the encryption bit stream to form a stream of encrypted data.
An apparatus for encrypting a stream data, comprising:
- a linear feedback shift register configured to produce an output according to a recurrence relation and a first non-linear function;
- a generator for altering the output of the linear feedback shift register according to a second non-linear function;
- and
- an execlusive-or (XOR) gate for XORing the stream of data with the output of the generator.
Dependencies are inferred from the claim text.