Frans Willems - Academia.edu (original) (raw)

Papers by Frans Willems

Research paper thumbnail of Multiple Observations for Secret-Key Binding with SRAM PUFs

Entropy, 2021

We present a new Multiple-Observations (MO) helper data scheme for secret-key binding to an SRAM-... more We present a new Multiple-Observations (MO) helper data scheme for secret-key binding to an SRAM-PUF. This MO scheme binds a single key to multiple enrollment observations of the SRAM-PUF. Performance is improved in comparison to classic schemes which generate helper data based on a single enrollment observation. The performance increase can be explained by the fact that the reliabilities of the different SRAM cells are modeled (implicitly) in the helper data. We prove that the scheme achieves secret-key capacity for any number of enrollment observations, and, therefore, it is optimal. We evaluate performance of the scheme using Monte Carlo simulations, where an off-the-shelf LDPC code is used to implement the linear error-correcting code. Another scheme that models the reliabilities of the SRAM cells is the so-called Soft-Decision (SD) helper data scheme. The SD scheme considers the one-probabilities of the SRAM cells as an input, which in practice are not observable. We present a ...

Research paper thumbnail of Searching methods for biometric identification systems: Fundamental limits

2009 IEEE International Symposium on Information Theory, 2009

Research paper thumbnail of Selection and balancing for debiasing of SRAM-PUF

Research paper thumbnail of Zero secrecy leakage for multiple enrollments of physical unclonable functions

We use physical unclonable functions (PUFs) to generate secret keys. We analyze the performance o... more We use physical unclonable functions (PUFs) to generate secret keys. We analyze the performance of the helper data scheme when the enrollment process is repeated multiple times. We show that codes exist such that the scheme remains secure after two enrollments, when all PUF observations are performed over the same channel. Furthermore, we show that a fuzzy commitment scheme remains secure after any number of enrollments, for PUF sources that meet a certain symmetry condition. We show that the temperature dependent model for SRAM-PUF meets this symmetry condition. Furthermore, we argue that many source-channel model pairs exist that meet the symmetry condition, and give some examples.

Research paper thumbnail of Probabilistic Shaping for Finite Blocklengths: Distribution Matching and Sphere Shaping

Entropy, 2020

In this paper, we provide a systematic comparison of distribution matching (DM) and sphere shapin... more In this paper, we provide a systematic comparison of distribution matching (DM) and sphere shaping (SpSh) algorithms for short blocklength probabilistic amplitude shaping. For asymptotically large blocklengths, constant composition distribution matching (CCDM) is known to generate the target capacity-achieving distribution. However, as the blocklength decreases, the resulting rate loss diminishes the efficiency of CCDM. We claim that for such short blocklengths over the additive white Gaussian noise (AWGN) channel, the objective of shaping should be reformulated as obtaining the most energy-efficient signal space for a given rate (rather than matching distributions). In light of this interpretation, multiset-partition DM (MPDM) and SpSh are reviewed as energy-efficient shaping techniques. Numerical results show that both have smaller rate losses than CCDM. SpSh—whose sole objective is to maximize the energy efficiency—is shown to have the minimum rate loss amongst all, which is part...

Research paper thumbnail of On the Downlink Capacity of Cell-Free Massive MIMO with Constrained Fronthaul Capacity

Entropy, 2020

We investigate the downlink of a cell-free massive multiple-in multiple-out system in which all a... more We investigate the downlink of a cell-free massive multiple-in multiple-out system in which all access points (APs) are connected in a linear-topolpgy fronthaul with constrained capacity and send a common message to a single receiver. By modeling the system as an extension of the multiple-access channel with partially cooperating encoders, we derive the channel capacity of the two-AP setting and then extend the results to arbitrary N-AP scenarios. By developing a cooperating mode concept, we investigate the optimal cooperation among the encoders (APs) when we limit the total fronthaul capacity, and the total transmit power is constrained as well. It is demonstrated that achieving capacity requires a water-pouring distribution of the total available fronthaul capacity over the fronthaul links. Our study reveals that a linear growth of total fronthaul capacity results in a logarithmic growth of the beamforming capacity. Moreover, even if the number of APs would be unlimited, only a fi...

Research paper thumbnail of Achievable Information Rates for Fiber Optics: Applications and Computations

Journal of Lightwave Technology, 2018

Research paper thumbnail of Capacity investigation of on–off keying in noncoherent channel settings at low SNR

Transactions on Emerging Telecommunications Technologies, 2015

On–off keying (OOK) has repossessed much new research interest to realize green communication for... more On–off keying (OOK) has repossessed much new research interest to realize green communication for establishing autonomous sensor networks. To realize ultra‐low power wireless design, we investigate the minimum energy per bit required for reliable communication of using OOK in a noncoherent channel setting where envelope detection is applied at the receiver. By defining different OOK channels with average transit power constraints, the achievability of the Shannon limit for both cases of using soft and hard decisions at the channel output is evaluated based on the analysis of the capacity per unit‐cost at low signal‐to‐noise ratio. We demonstrate that in phase fading using hard decisions cannot destroy the capacity only if extremely asymmetric OOK inputs are used with a properly chosen threshold. The corresponding pulse‐position modulation scheme is explicitly studied and demonstrated to be a Shannon‐type solution. Moreover, we also consider a slow Rayleigh fading scenario where the ...

Research paper thumbnail of Reversible Information Embedding, Theory and Practice

Research paper thumbnail of Information Theoretical Analysis of Identification based on Active Content Fingerprinting

Research paper thumbnail of Two-Dimensional Iterative Processing for DAB Receivers Based on Trellis-Decomposition

Journal of Electrical and Computer Engineering, 2012

We investigate iterative trellis decoding techniques for DAB, with the objective of gaining from ... more We investigate iterative trellis decoding techniques for DAB, with the objective of gaining from processing 2D-blocks in an OFDM scheme, that is, blocks based on the time and frequency dimension, and from trellis decomposition. Trellis-decomposition methods allow us to estimate the unknown channel phase since this phase relates to the sub-trellises. We will determine a-posteriori sub-trellis probabilities, and use these probabilities for weighting the a-posteriori symbol probabilities resulting from all the sub-trellises. Alternatively we can determine a dominant sub-trellis and use the a-posteriori symbol probabilities corresponding to this dominant sub-trellis. This dominant sub-trellis approach results in a significant complexity reduction. We will investigate both iterative and non-iterative methods. The advantage of non-iterative methods is that their forwardbackward procedures are extremely simple; however, also their gain of 0.7 dB, relative to two-symbol differential detecti...

Research paper thumbnail of Joint and iterative detection and decoding of differentially encoded COFDM systems

2010 17th International Conference on Telecommunications, 2010

Research paper thumbnail of Bit-Interleaved Coded Modulation Revisited: A Mismatched Decoding Perspective

IEEE Transactions on Information Theory, 2009

Research paper thumbnail of Partial feedback for the discrete memoryless multiple access channel (Corresp.)

IEEE Transactions on Information Theory, 1983

Research paper thumbnail of Semantic coding: Partial transmission

2008 IEEE International Symposium on Information Theory, 2008

DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

Research paper thumbnail of On the capacity of a biometrical identification system

IEEE International Symposium on Information Theory, 2003. Proceedings., 2003

We investigate fundamental properties of biometrical identification systems. We focus on the capa... more We investigate fundamental properties of biometrical identification systems. We focus on the capacity, i.e. a measure for the number of individuals that can be reliably identified. It can be expressed using standard information-theoretical concepts.

Research paper thumbnail of Coding theorems for reversible embedding

DIMACS Series in Discrete Mathematics and Theoretical Computer Science, 2004

We consider embedding of messages (data-hiding) into i.i.d. host sequences. As in Fridrich et al.... more We consider embedding of messages (data-hiding) into i.i.d. host sequences. As in Fridrich et al. [2002] we focus on the case where reconstruction of the host sequence from the composite sequence is required. We study the balance between embedding rate and embedding distortion. First we determine the distortion-rate region corresponding to this setup. Then we generalize this result in two directions. (A) The reversible embedding setup is not robust. Therefore we also consider reconstruction based on the output sequence of a discrete memoryless channel whose input is the composite sequence. We also determine the distortion-rate region for this setup. (B) Then we consider the case where only partial reconstruction of the host sequence is required. We determine the possible trade-offs here between embedding rate, distortion between source sequence and composite sequence (embedding distortion), and distortion between source sequence and restoration sequence (restoration distortion), i.e. the distortion-rate region. All achievability proofs in this paper are based on the Gelfand-Pinsker [1980] achievability proof.

Research paper thumbnail of Fundamental limits of identification: Identification rate, search and memory complexity trade-off

2013 IEEE International Symposium on Information Theory, 2013

In this paper, we introduce a new generalized scheme to resolve the trade-off between the identif... more In this paper, we introduce a new generalized scheme to resolve the trade-off between the identification rate, search and memory complexities in large-scale identification systems. The main contribution of this paper consists in a special database organization based on assigning entries of a database to a set of predefined and possibly overlapping clusters, where the cluster representative points are generated based on statistics of both entries of the database and queries. The decoding procedure is accomplished in two stages: At the first stage, a list of clusters related to the query is estimated, then refinement checks are performed to all members of these clusters to produce a unique index at the second stage. The proposed scheme generalizes several practical searching in identification systems as well as makes it possible to approach a new achievable region of searchmemory complexity trade-off.

Research paper thumbnail of Fundamental Limits for Privacy-Preserving Biometric Identification Systems That Support Authentication

IEEE Transactions on Information Theory, 2015

DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

Research paper thumbnail of Privacy-leakage codes for biometric authentication systems

2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2014

In biometric privacy-preserving authentication systems that are based on key-binding, two termina... more In biometric privacy-preserving authentication systems that are based on key-binding, two terminals observe two correlated biometric sequences. The first terminal selects a secret key, which is independent of the biometric data, binds this secret key to the observed biometric sequence and communicates it to the second terminal by sending a public message. This message should only contain a negligible amount of information about the secret key, but also leak as little as possible about the biometric data. Current approaches to realize such biometric systems use fuzzy commitment with codes that, given a secret-key rate, can only achieve the corresponding privacy-leakage rate equal to one minus this secret-key rate. However, the results in Willems and Ignatenko [2009] indicate that lower privacy leakage can be achieved if vector quantization is used at the encoder. In this paper we study the use of convolutional and turbo codes applied in fuzzy commitment and its modifications that realize this.

Research paper thumbnail of Multiple Observations for Secret-Key Binding with SRAM PUFs

Entropy, 2021

We present a new Multiple-Observations (MO) helper data scheme for secret-key binding to an SRAM-... more We present a new Multiple-Observations (MO) helper data scheme for secret-key binding to an SRAM-PUF. This MO scheme binds a single key to multiple enrollment observations of the SRAM-PUF. Performance is improved in comparison to classic schemes which generate helper data based on a single enrollment observation. The performance increase can be explained by the fact that the reliabilities of the different SRAM cells are modeled (implicitly) in the helper data. We prove that the scheme achieves secret-key capacity for any number of enrollment observations, and, therefore, it is optimal. We evaluate performance of the scheme using Monte Carlo simulations, where an off-the-shelf LDPC code is used to implement the linear error-correcting code. Another scheme that models the reliabilities of the SRAM cells is the so-called Soft-Decision (SD) helper data scheme. The SD scheme considers the one-probabilities of the SRAM cells as an input, which in practice are not observable. We present a ...

Research paper thumbnail of Searching methods for biometric identification systems: Fundamental limits

2009 IEEE International Symposium on Information Theory, 2009

Research paper thumbnail of Selection and balancing for debiasing of SRAM-PUF

Research paper thumbnail of Zero secrecy leakage for multiple enrollments of physical unclonable functions

We use physical unclonable functions (PUFs) to generate secret keys. We analyze the performance o... more We use physical unclonable functions (PUFs) to generate secret keys. We analyze the performance of the helper data scheme when the enrollment process is repeated multiple times. We show that codes exist such that the scheme remains secure after two enrollments, when all PUF observations are performed over the same channel. Furthermore, we show that a fuzzy commitment scheme remains secure after any number of enrollments, for PUF sources that meet a certain symmetry condition. We show that the temperature dependent model for SRAM-PUF meets this symmetry condition. Furthermore, we argue that many source-channel model pairs exist that meet the symmetry condition, and give some examples.

Research paper thumbnail of Probabilistic Shaping for Finite Blocklengths: Distribution Matching and Sphere Shaping

Entropy, 2020

In this paper, we provide a systematic comparison of distribution matching (DM) and sphere shapin... more In this paper, we provide a systematic comparison of distribution matching (DM) and sphere shaping (SpSh) algorithms for short blocklength probabilistic amplitude shaping. For asymptotically large blocklengths, constant composition distribution matching (CCDM) is known to generate the target capacity-achieving distribution. However, as the blocklength decreases, the resulting rate loss diminishes the efficiency of CCDM. We claim that for such short blocklengths over the additive white Gaussian noise (AWGN) channel, the objective of shaping should be reformulated as obtaining the most energy-efficient signal space for a given rate (rather than matching distributions). In light of this interpretation, multiset-partition DM (MPDM) and SpSh are reviewed as energy-efficient shaping techniques. Numerical results show that both have smaller rate losses than CCDM. SpSh—whose sole objective is to maximize the energy efficiency—is shown to have the minimum rate loss amongst all, which is part...

Research paper thumbnail of On the Downlink Capacity of Cell-Free Massive MIMO with Constrained Fronthaul Capacity

Entropy, 2020

We investigate the downlink of a cell-free massive multiple-in multiple-out system in which all a... more We investigate the downlink of a cell-free massive multiple-in multiple-out system in which all access points (APs) are connected in a linear-topolpgy fronthaul with constrained capacity and send a common message to a single receiver. By modeling the system as an extension of the multiple-access channel with partially cooperating encoders, we derive the channel capacity of the two-AP setting and then extend the results to arbitrary N-AP scenarios. By developing a cooperating mode concept, we investigate the optimal cooperation among the encoders (APs) when we limit the total fronthaul capacity, and the total transmit power is constrained as well. It is demonstrated that achieving capacity requires a water-pouring distribution of the total available fronthaul capacity over the fronthaul links. Our study reveals that a linear growth of total fronthaul capacity results in a logarithmic growth of the beamforming capacity. Moreover, even if the number of APs would be unlimited, only a fi...

Research paper thumbnail of Achievable Information Rates for Fiber Optics: Applications and Computations

Journal of Lightwave Technology, 2018

Research paper thumbnail of Capacity investigation of on–off keying in noncoherent channel settings at low SNR

Transactions on Emerging Telecommunications Technologies, 2015

On–off keying (OOK) has repossessed much new research interest to realize green communication for... more On–off keying (OOK) has repossessed much new research interest to realize green communication for establishing autonomous sensor networks. To realize ultra‐low power wireless design, we investigate the minimum energy per bit required for reliable communication of using OOK in a noncoherent channel setting where envelope detection is applied at the receiver. By defining different OOK channels with average transit power constraints, the achievability of the Shannon limit for both cases of using soft and hard decisions at the channel output is evaluated based on the analysis of the capacity per unit‐cost at low signal‐to‐noise ratio. We demonstrate that in phase fading using hard decisions cannot destroy the capacity only if extremely asymmetric OOK inputs are used with a properly chosen threshold. The corresponding pulse‐position modulation scheme is explicitly studied and demonstrated to be a Shannon‐type solution. Moreover, we also consider a slow Rayleigh fading scenario where the ...

Research paper thumbnail of Reversible Information Embedding, Theory and Practice

Research paper thumbnail of Information Theoretical Analysis of Identification based on Active Content Fingerprinting

Research paper thumbnail of Two-Dimensional Iterative Processing for DAB Receivers Based on Trellis-Decomposition

Journal of Electrical and Computer Engineering, 2012

We investigate iterative trellis decoding techniques for DAB, with the objective of gaining from ... more We investigate iterative trellis decoding techniques for DAB, with the objective of gaining from processing 2D-blocks in an OFDM scheme, that is, blocks based on the time and frequency dimension, and from trellis decomposition. Trellis-decomposition methods allow us to estimate the unknown channel phase since this phase relates to the sub-trellises. We will determine a-posteriori sub-trellis probabilities, and use these probabilities for weighting the a-posteriori symbol probabilities resulting from all the sub-trellises. Alternatively we can determine a dominant sub-trellis and use the a-posteriori symbol probabilities corresponding to this dominant sub-trellis. This dominant sub-trellis approach results in a significant complexity reduction. We will investigate both iterative and non-iterative methods. The advantage of non-iterative methods is that their forwardbackward procedures are extremely simple; however, also their gain of 0.7 dB, relative to two-symbol differential detecti...

Research paper thumbnail of Joint and iterative detection and decoding of differentially encoded COFDM systems

2010 17th International Conference on Telecommunications, 2010

Research paper thumbnail of Bit-Interleaved Coded Modulation Revisited: A Mismatched Decoding Perspective

IEEE Transactions on Information Theory, 2009

Research paper thumbnail of Partial feedback for the discrete memoryless multiple access channel (Corresp.)

IEEE Transactions on Information Theory, 1983

Research paper thumbnail of Semantic coding: Partial transmission

2008 IEEE International Symposium on Information Theory, 2008

DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

Research paper thumbnail of On the capacity of a biometrical identification system

IEEE International Symposium on Information Theory, 2003. Proceedings., 2003

We investigate fundamental properties of biometrical identification systems. We focus on the capa... more We investigate fundamental properties of biometrical identification systems. We focus on the capacity, i.e. a measure for the number of individuals that can be reliably identified. It can be expressed using standard information-theoretical concepts.

Research paper thumbnail of Coding theorems for reversible embedding

DIMACS Series in Discrete Mathematics and Theoretical Computer Science, 2004

We consider embedding of messages (data-hiding) into i.i.d. host sequences. As in Fridrich et al.... more We consider embedding of messages (data-hiding) into i.i.d. host sequences. As in Fridrich et al. [2002] we focus on the case where reconstruction of the host sequence from the composite sequence is required. We study the balance between embedding rate and embedding distortion. First we determine the distortion-rate region corresponding to this setup. Then we generalize this result in two directions. (A) The reversible embedding setup is not robust. Therefore we also consider reconstruction based on the output sequence of a discrete memoryless channel whose input is the composite sequence. We also determine the distortion-rate region for this setup. (B) Then we consider the case where only partial reconstruction of the host sequence is required. We determine the possible trade-offs here between embedding rate, distortion between source sequence and composite sequence (embedding distortion), and distortion between source sequence and restoration sequence (restoration distortion), i.e. the distortion-rate region. All achievability proofs in this paper are based on the Gelfand-Pinsker [1980] achievability proof.

Research paper thumbnail of Fundamental limits of identification: Identification rate, search and memory complexity trade-off

2013 IEEE International Symposium on Information Theory, 2013

In this paper, we introduce a new generalized scheme to resolve the trade-off between the identif... more In this paper, we introduce a new generalized scheme to resolve the trade-off between the identification rate, search and memory complexities in large-scale identification systems. The main contribution of this paper consists in a special database organization based on assigning entries of a database to a set of predefined and possibly overlapping clusters, where the cluster representative points are generated based on statistics of both entries of the database and queries. The decoding procedure is accomplished in two stages: At the first stage, a list of clusters related to the query is estimated, then refinement checks are performed to all members of these clusters to produce a unique index at the second stage. The proposed scheme generalizes several practical searching in identification systems as well as makes it possible to approach a new achievable region of searchmemory complexity trade-off.

Research paper thumbnail of Fundamental Limits for Privacy-Preserving Biometric Identification Systems That Support Authentication

IEEE Transactions on Information Theory, 2015

DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

Research paper thumbnail of Privacy-leakage codes for biometric authentication systems

2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2014

In biometric privacy-preserving authentication systems that are based on key-binding, two termina... more In biometric privacy-preserving authentication systems that are based on key-binding, two terminals observe two correlated biometric sequences. The first terminal selects a secret key, which is independent of the biometric data, binds this secret key to the observed biometric sequence and communicates it to the second terminal by sending a public message. This message should only contain a negligible amount of information about the secret key, but also leak as little as possible about the biometric data. Current approaches to realize such biometric systems use fuzzy commitment with codes that, given a secret-key rate, can only achieve the corresponding privacy-leakage rate equal to one minus this secret-key rate. However, the results in Willems and Ignatenko [2009] indicate that lower privacy leakage can be achieved if vector quantization is used at the encoder. In this paper we study the use of convolutional and turbo codes applied in fuzzy commitment and its modifications that realize this.