Abstract: Some embodiments are directed to an electronic cryptographic device configured to determine a cryptographic key. The cryptographic device has a physically unclonable function, a debiasing unit, and a key reconstruction unit. The PUF is configured to produce a first noisy bit string during an enrollment phase and a second noisy bit string during a reconstruction phase. The debiasing unit (120) is configured to determine debiasing data from the first noisy bit string during the enrollment phase. The debiasing data marks bits in the first noisy bit string as retained or discarded. The key reconstruction unit is configured to determine the cryptographic key from bits in the second noisy bit string marked as retained by the debiasing data, the cryptographic key being independent from bits in the second noisy bit string marked as discarded by the debiasing data.

Abstract: Some embodiments are directed to an electronic cryptographic device configured to determine a cryptographic key. The cryptographic device has a physically unclonable function, a debiasing unit, and a key reconstruction unit. The PUF is configured to produce a first noisy bit string during an enrollment phase and a second noisy bit string during a reconstruction phase. The debiasing unit (120) is configured to determine debiasing data from the first noisy bit string during the enrollment phase. The debiasing data marks bits in the first noisy bit string as retained or discarded. The key reconstruction unit is configured to determine the cryptographic key from bits in the second noisy bit string marked as retained by the debiasing data, the cryptographic key being independent from bits in the second noisy bit string marked as discarded by the debiasing data.

Abstract: The invention relates to a method for use in a packet-switched communication system, the method comprising: sending a first packet from a source node to a destination node, the first packet containing a first set of data bits; sending a second packet from the source node to the destination node, the second packet containing a second set of data bits; wherein, in the event that the first set of data bits cannot be successfully decoded in the destination node, the second packet further comprises a first set of error correction bits for the first set of data bits.

Abstract: The invention relates to a method of authentication of a physical object and an apparatus applying said method. The method uses a helper data (W1) and a control value (V1) associated with a reference object to generate a first property set (C1) using the helper data (W1) and a metric (Y) associated with the physical object. It further comprises a step to generate a second property set (S1) using a noise compensating mapping (NCM) on the first property set (C1), as well as a step to establish a sufficient match between the physical object and the reference object using the second property set (S1) and the first control value (V1). The method is characterized by a step that generates an error measure (ERR) by quantifying the noise removed by the noise compensating mapping (NCM) using the first property set (C1) and information derived from the noise compensating mapping (NCM). Error measure (ERR) is subsequently used for generating an authentication decision (D).

Abstract: Described is a transmission system (10) for transmitting an information signal (21) via a plurality of subchannels from a transmitter (12) to a receiver (16). The transmitter (12) first demultiplexes the information signal (21) into a plurality of information subsignals (33). Next, the information subsignals (33) are encoded according to a code with certain properties, e.g. a maximum distance separable (MDS) code, and multiplexed. Finally, the resulting subsignals (31) are channel encoded and transmitted to the receiver (16). The receiver (16) comprises a channel decoder (46,52,76,128) for successively channel decoding the received subsignals by incorporating decoding information (83,87,91) of already channel decoded information subsignals. Next, the resulting subsignals are demultiplexed, decoded according to said code and multiplexed into an output signal.

Abstract: The invention relates to a method for use in a packet-switched communication system, the method comprising: sending a first packet from a source node to a destination node, the first packet containing a first set of data bits; sending a second packet from the source node to the destination node, the second packet containing a second set of data bits; wherein, in the event that the first set of data bits cannot be successfully decoded in the destination node, the second packet further comprises a first set of error correction bits for the first set of data bits.

Abstract: The invention relates to a method of authentication of a physical object and an apparatus applying said method. The method uses a helper data (W1) and a control value (V1) associated with a reference object to generate a first property set (C1) using the helper data (W1) and a metric (Y) associated with the physical object. It further comprises a step to generate a second property set (S1) using a noise compensating mapping (NCM) on the first property set (C1), as well as a step to establish a sufficient match between the physical object and the reference object using the second property set (S1) and the first control value (V1). The method is characterized by a step that generates an error measure (ERR) by quantifying the noise removed by the noise compensating mapping (NCM) using the first property set (C1) and information derived from the noise compensating mapping (NCM). Error measure (ERR) is subsequently used for generating an authentication decision (D).

Abstract: Information signals such as grayscale images or audio signals are represented as a sequence of PCM signal samples. To embed auxiliary data in the least significant bits of the signal, the samples are slightly distorted. There is a so-termed “rate-distortion function” (20) which gives the largest embedding rate R given a certain distortion level D. It appears that the efficiency of prior art embedding schemes such as LSB replacement (21,22) can be improved. The invention discloses such embedding schemes (23,24). According to the invention, the signal is divided into groups of L (L>1) signal samples (x). For each group of signal samples, a vector of least significant portions (x mod n) of the signal samples is created. For n=2, the vector comprises the least significant bit of each signal sample. The syndrome of said vector (as defined in the field of error detection and correction) represents the embedded data.

Abstract: The invention discloses a method of embedding information for high quality restoration of a media signal (typically an audio-visual signal) in a lower quality version of the signal. To this end, the signal x is encoded using a high quality encoder (Q2). The code sequences z produced by the high quality encoder are mapped into code sequences y that are associated with a hypothetical lower quality encoder (Q1). The latter code sequences y are transmitted. A simple decoder will decode the received sequences y, and thus reproduce a low quality version of the signal. A more sophisticated decoder is arranged to inversely map the received code sequences y into the code sequences z, that were actually produced by the high quality encoder (Q2). The sophisticated decoder will thus reproduce a higher quality version of the same signal.

Abstract: Known systems use two probability signals for coding an input signal into an output signal and for decoding said output signal into the input signal. In a first memory field two probability signals are stored, and in a second memory field two other probability signals are stored, and in response to a further received symbol processor means adapt the probability signals. Such a system needs a giant memory capacity, which can be reduced by combining probability signals into a first combination signal to be stored in the first memory field and by combining further probability signals into a second combination signal to be stored in the second memory field, and by converting a third combination signal into at least one probability signal just before (de)coding takes place.

Abstract: Known methods for construct a tree, for a context tree algorithm for coding symbols, construct trees by adding nodes. These methods need a giant memory capacity, which can be reduced in case unnecessary nodes are not added to the tree. This should be done through dependence on values of parameters belonging to a node where each parameter defines a number of symbols received that have a certain value.

Abstract: Known systems use two probability signals for coding an input signal into an output signal and for decoding said output signal into the input signal. In a first memory field two probability signals are stored, and in a second memory field two other probability signals are stored, and in response to a further received symbol processor means adapt the probability signals. Such a system needs a giant memory capacity, which can be reduced by combining probability signals into a first combination signal to be stored in the first memory field and by combining further probability signals into a second combination signal to be stored in the second memory field, and by converting a third combination signal into at least one probability signal just before (de)coding takes place.