Abstract:
An encryption process comprises the following steps:
preliminarily choosing at least a secret key and a set of permutable functions defined on a certain phase space for encrypting/decrypting messages, choosing a code for encoding messages to be sent in the form of a number belonging to the phase space, and wherein the set of permutable functions is composed of modified chaotic maps generated by a composite function, the image of which is calculated modulo a certain pre-established integer number, obtained composing a first function, a second function and the inverse of said first function,
the secret key is defined by using the second function.
This process uses a particular type of chaotic maps, the "modified chaotic maps", that work only on integer numbers. Given that operations on integers are faster than operations in floating-point arithmetic, this encryption process is faster than other processes that use chaotic maps.
Abstract:
An encryption process which is both secure and practical, does not require modular arithmetic, and therefore is very fast, and may be used for realizing a digital signature process, comprises the following steps:
choosing preliminarily at least a private key and a set of permutable functions defined on a certain phase space for encrypting/decrypting messages, choosing a code for encoding messages to be sent in the form of a number belonging to the phase space, and wherein the set of permutable functions is composed of chaotic maps generated by a composite function of a first function, a second function and the inverse of the first function, the private key is defined by using the second function.
It is possible to implement public-key encryption processes and related digital signature processes using chaotic maps by a computer program.
Abstract:
A method of generating cryptographically secure (or unpredictable) pseudo-random numbers uses simple functions whose inverse is not a well-defined function and has a large number of branches, although the inverse could be easily computed on each particular branch. In this way the sequence of numbers is practically unpredictable and at the same time may be generated using very simple functions. A hardware generator of chaos-based pseudo random bit sequences implementing an embodiment of the method comprises:
― circuit means for storing bit strings representing integer numbers of the pseudo-random sequence; ― a shift register coupled to the circuit means; ― a command circuit generating shift commands for the shift register; ― second circuit means for storing the bits output by the shift register; ― an adder modulo 2 summing the bits stored in the second circuit means, generating a bit of the chaos-based pseudo-random bit sequence; ― a second adder summing up the bit strings currently stored in the shift register and in the first circuit means, generating a bit string representing a successive number of the pseudo-random sequence.
Abstract:
In an encryption/decryption system for converting data signals between an unencrypted plaintext format and an encrypted ciphertext format plurality of round modules are provided (10) permitting a respective set of input data signals (TEXT IN) to generate a respective set of output data signals (TEXT OUT) by means of transformation controlled by a round key (SUBKEY). The transformation is identified by at least one map function derived from a chaotic map (14).
Abstract:
A method for generating a random number sequence whose randomness properties are determined a priori , comprises the steps of defining a parametric map; calculating, in function of parameters of the map, the entropy and the Lyapunov exponent of random number sequences obtainable using the parametric map; identifying at least a set of values of parameters for which the entropy and the Lyapunov exponent are positive numbers the map has no attracting point; assigning a pre-established value as a first feedback value and carrying out cyclically the following steps for generating a random number sequence:
(i) determining said parameters inside the set as the numerical values of respective physical quantities; (ii) outputting a random number, according to said map with the parameters and the assigned feedback value; (iii) assigning as new feedback value said output random number.
A circuit, preferably realized using a switched current technique, implements the method of the invention for generating a random bit sequence.