摘要:
The present invention relates to a yoke ring for use in a deflection unit in a cathode ray tube (CRT). The yoke ring having a neck and a flared side, and being defined by an inner and an outer contour. According to the invention, the inner contour is periodically deformed in the radial direction, the contour having at least two local minima and maxima. This deformation influences the magnetic field generated by the coils in the CRT, leading to improved front-of-screen performance. In particular, astigmatism, coma and raster errors are reduced.
摘要:
A method of encrypting data using a first key and multiple encryption keys at least in part based on the first key. The method includes encoding the data into a redundant representation by distributing the information content of the data among a number of groups, each group being associated with a respective encryption key of the multiple encryption keys, each encryption key being associated with at least one group, the redundant representation allowing recovery of the data in the absence of the groups associated with the at least one of the multiple encryption keys, and encrypting each group by the respective associated encryption key.
摘要:
A method of and system (110) for controlled activation of at least one function in a product or component at a remote location, which activation requires a correct activation data item to be available in the product or component. The method comprises receiving one or more noisy outputs of an unclonable element associated with the component from the remote location, and providing helper data to the remote location, which helper data transforms the one or more noisy outputs to a single value which corresponds to the correct activation data item.
摘要:
A distribution system and method for distributing digital information is provided, which has high recoverability from a security breach. The distribution system comprises a server (200) and a computing device (110). During an enrollment phase, the computing device obtains a first response from an integrated physically unclonable function (150) integrated in the computing device. The system comprises an enrollment module (130) for determining helper data from a decryption key and the first response to enable later reconstruction of the decryption key from the helper data and a second response obtained from the physically unclonable function. During a reconstruction phase, which occurs after the enrollment phase and typically after a security breach has occurred that revealed data and/or programming code of the computing device, the server may encrypt digital information using an encryption module (220) with a cryptographic encryption key corresponding to the decryption key.
摘要:
A method and a device of verifying the validity a digital signature based on biometric data. A verifier attains a first biometric template of the individual to be verified, for instance by having the individual provide her fingerprint via an appropriate sensor device. Then, the verifier receives a digital signature and a second biometric template. The verifier then verifies the digital signature by using either the first or the second biometric template as a public key. The attained (first) biometric template of the individual is compared with the received (second) biometric template associated with the signature and if a match occurs, the verifier can be confident that the digital signature and the associated (second) biometric template have not been manipulated by an attacker for impersonation purposes.
摘要:
The invention relates to a method for proving authenticity of a prover PRV to a verifier VER, the method comprising generating a secret S using a physical token by the prover PRV. Obtaining a public value PV by the verifier, where the public value PV has been derived from the secret S using a function for which the inverse of said function is computationally expensive. The method further comprising a step for conducting a zero knowledge protocol between the prover PRV and the verifier VER in order to prove to the verifier VER, with a pre-determined probability, that the prover PRV has access to the physical token, where the prover PRV makes use of the secret S and the verifier VER makes use of the public value PV. The invention further relates to a system employing the method, and an object for proving authenticity.
摘要:
The invention provides a method of generating arbitrary numbers given a seed, characterized by providing a challenge derived from the seed to a physical token, receiving an initial response from the physical token, combining the initial response with helper data associated with the challenge to produce a stable response, and generating the arbitrary numbers using a pseudo-random number generator using the stable response as a seed for the generator. Preferably one or more of these pseudo-random permutations are used as one or more round function(s) in a Feistel block cipher. The generated arbitrary numbers may also be used to create a cryptographic key.
摘要:
There is provided a method of generating a key for encrypting Communications between first and second terminals comprising obtaining a measurement of characteristics of a physical identifier of a user; and extracting a key from the physical identifier using a code selected from a collection of codes, each code in the collection defining an ordered mapping from a set of values of the characteristics to a set of keys; wherein the collection of codes comprises at least one code in which the ordered mapping is a permutation of the ordered mapping of one of the other codes in the collection.
摘要:
The present invention relates to a method of creating challenge-response pairs, a method of authenticating a plurality of physical tokens, a system for creating challenge-response pairs and a device for authenticating a plurality of physical tokens. A basic idea of the invention is to interconnect a plurality of physical tokens (101, 102, 103), such as a plurality of uncloneable functions (PUFs), in a sequence, provide the sequence with a challenge (Q and use a response of a PUF as a challenge to a subsequent PUF in the sequence. When a final PUF is reached in the sequence and produces a response (R), a challenge-response pair (CRP) has been created, which pair comprises the challenge provided to the sequence of PUFs and the response produced by the final PUF. At least the challenge of this CRP is then stored.
摘要:
A security element comprises at least one oscillating circuit (O1-On) and a digital signature (2). Each oscillating circuit (O1-On) comprises a capacitor (C1-Cn) as resonance frequency setting element wherein the capacitor (C1-Cn) consists of two electrodes (8, 10) which are spaced apart from each other and a dielectric (9) that is sandwiched between the two electrodes (8, 10). The capacitor (C1-Cn) of each oscillating circuit has a random capacitance value which randomness is caused by a non-uniform thickness (d) of the dielectric (9) and/or by an inhomogeneous dielectric material. The digital signature (2) comprises reference values indicative for the resonance frequencies (f1-fh) of the oscillating circuits wherein the reference values are digitally signed with a secret key.