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e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 3.3 Abbreviations | For the purposes of the present document, the following abbreviations apply: AP Access Point BCI Brain-Computer Interface BER Bit Error Rate EAP Extracellular Action Potentials ECoG Electrocorticography EEG ElectroEncephaloGraphy MEG Magneto-Encephalon-Graphy MRI Magnetic Resonance Imaging NFC Near-Field Communication ... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 4 BCI overview | The use case of BCI targets the development and application of innovative neural technologies to advance the resolution of neural recording and stimulation toward the dynamic mapping of brain activity and neural processing. These advanced neuro-technologies will enable new studies and experiments to advance the current... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5 BCI system considerations | |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.1 Energy source | |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.1.0 Introduction | The constrained environment around the brain presents an energy source challenge. Indeed, one of the major challenges on implantable μECoG arrays for BCI nodes is how to power such implantable devices. Even logistically, it is an issue. For example, the electrode array is placed on the cortex, while the other component... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.1.1 Battery | Another implantable application such as pacemakers has used batteries extensively. However, it makes sense to use a battery in a pacemaker, because the required power is relatively small (microwatts) and there is a large physical area available such that a battery can last 10 years or more. ETSI ETSI TR 103 952 V1.1.1 ... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.1.2 Energy harvesting | Harvesting energy from ambient sources in local environments has been studied as a potential power source option. Some scavenging methods include solar cells, biofuel cells, thermoelectric generators, piezoelectric generators, and ambient RF. While such approaches are theoretically attractive for implant neural devices... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.1.3 Wireless power transfer | The most promising means to power an implanted device with higher power requirements than pacemakers is to deliver energy wirelessly via a transcutaneous link, also known as Wireless Power Transfer (WPT). A transcutaneous link may use light (typically near-infrared light), or acoustics (typically at ultrasound frequenc... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.2 Communication interface | |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.2.0 Introduction | ECoG devices convey the acquired data to an external controller or Access Point (AP) via a wireless link, where the information can be processed and monitored for diverse applications from healthcare providers to scientific research. In contrast to conventional star topologies, an ECoG network supports more traffic (ag... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.2.1 Backscatter communication in the near field | Near-field communications operate at distances about one wavelength of the carrier frequency. Hence, it is suitable when the AP is located on the head, for instance, on virtual reality goggles. In addition, WPT can be integrated easily. Regarding the WPT for the downlink (AP to device), the backscattering method is one... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.2.2 ECoG wireless links | The processing, power, and size-constrained ECoG devices lead toward short-range wireless links. Moreover, ECoG devices typically have a depth of a few cm and high-throughput neural recording. Hence, WPT is a natural choice as the primary mode of power transfer due to its high efficiency and robustness in comparison to... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.3 Body Tera Hertz networks | |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.3.0 Introduction | Covering significant portions of the brain with an adequate sampling resolution will require a high throughput to be handled adequately for one central unit with significant processing and power constraints. Therefore, researching the use of THz technology for WPT and data communication is due to the recent advances in... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.3.1 Enhancements to channel modeling | THz technologies still face various challenges. Among others, the propagation characteristics of THz channels. Contributions describing THz channel measurements and modeling indicate [i.9]: • Path loss and shadowing (large-scale) parameters in THz bands exhibit specific features compared to frequencies below 100 GHz. T... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.3.2 Electronic and photonic technologies | |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.3.2.0 Introduction | THz bands are promising candidates for future radio systems due to potential applications beyond high data rate capacity, such as integrated sensing and imaging. However, it has been difficult to generate intensive, directional THz radiation. Figure 10 shows the emission power vs. frequency for various electronic and p... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.3.2.1 Electronic sources | Electronic sources have advanced in the past years, especially with the refinement of various semiconductor materials. For example, frequency multiplier chains with Resonant Tunneling Diodes (RTD). However, still they have certain limitations in bandwidth and efficiency. |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 5.3.2.2 Photonic sources | There are two methods of generating THz radiation using photonic devices: • Direct THz generation with optical sources includes the Quantum Cascade Laser (QCL) or nonlinear optics that directly generate THz radiation. Reasonable power levels can be reached with QCL, but the efficiency is still limited as they operate a... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 6 Design considerations | |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 6.0 General | To continue the development of BCI wireless applications, it is explored the feasibility of [sub] THz technologies for wireless data signaling and WPT as follows: • Selecting the [sub] THz spectrum of interest. • Experimental studies to determine Specific Absorption Rate (SAR) and propagation effects of [sub] THz radia... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 6.1 Selecting THz frequency bands | |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 6.1.1 General | Due to the wide frequency range for the THz band, practical application for BCI is likely to use a subband. Hence, selecting THz frequency bands is an important design item. An overview of the process taken by ITU during the World Radiocommunication Conference of 2023 (WRC-23) is important as it impacts radio regulatio... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 6.1.2 WRC-23 AI 1.14 | 231.5 GHz 232 GHz 239.2 GHz 235 GHz 238 GHz 7.7 GHz spectrum for THz apps Already allocated EESS without protection New allocation for mobile and fixed co-primary services Figure 12: Outcome AI 1.14 a) The new spectrum allocation between 232 GHz and 239,2 GHz has been allocated for mobile and fixed services on a co-pri... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 6.1.3 WRC-27 AI 1.8 | 231.5 GHz 275 GHz 700 GHz Call: studies for new allocations Call: identification of new allocations Radio location services Figure 13: Outcome of AI 1.8 a) Resolution 663 (Rev. WRC-23 [i.10]) discusses studies of possible new allocations in the frequency band 231,5 GHz to 275 GHz and identifications for radio location ... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 6.1.4 WRC-23 resolution 731 | 71 GHz Consideration of sharing and adjacent- band compatibility between passive and active services update Conditions for Interference management of land-mobile, fixed services to protect EESS WRC-2023 Resolution 731 296 GHz 306 GHz 313 GHz 318 GHz 333 GHz 356 GHz Figure 14: Outcome resolution 731 a) Resolution 731 (R... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 6.1.5 WRC-31 Potential New AI | 275 GHz 325 GHz Studies on potential new allocations WRC-31 Resolution COM 6/13 Figure 15: Outcome resolution com 6/13 a) Resolution COM 6/13 (WRC-23 [i.10]): Studies on potential new allocations for fixed, mobile, radiolocation, amateur, amateur-satellite, radio astronomy, Earth exploration-satellite (passive and acti... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 6.2 Photonic technology in THz transmission | |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 6.2.1 Overview | Future wireless systems require high wireless data communication capacity that involves immersive virtual and extended reality, as well as medical applications in BCI use cases. Figure 16 shows persons with goggles, but the aim of future BCIs is for headbands or glasses. Figure 16: Immersive virtual and extended realit... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 6.2.2 Technical challenges | A popular approach is to use InP/InGaAs Uni-Traveling-Carrier Photodiode (UTC-PD) to generate THz signals. However, a known technical challenge is the generation of output power to compensate for THz attenuation, Figure 20. Another technical challenge is the miniaturization and integration in a small form factor fabric... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7 Aspects of THz radio propagation | |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7.1 General | Channel models for THz communications and sensing depend on the frequency bands of interest, which in turn depend on the deployment scenario Next frequency bands are discussed. |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7.2 Frequency bands | As mentioned in a previous clause, THz frequency ranges from 100 GHz to 10 THz (0,03 mm to 3 mm wavelength). Frequencies below the THz spectrum consist of the mm-wave spectrum and microwave spectrum. Those frequency bands are heavily utilized for many types of communication and radar applications. Above the THz spectru... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7.3 Channel modeling approaches | |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7.3.1 General | Conventional wireless systems design relies on accurate simulation of radio propagation effects or channel modeling. It provides insights into the behavior performance and dependability of wireless systems and consequently, it enables the development of innovative technologies. Considering electromagnetic propagation, ... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7.3.2.0 Introduction | The ETSI TR 138 901 [i.1] channel model document provides a probabilistic channel model for frequency bands ranging from 0,5 GHz to 100 GHz. It has been useful for designing, optimizing, and evaluating 5G system designs for various physical layer enhancements. It supports simple stochastic channel models (Tapped Delay ... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7.3.2.1 Frequency range up to 100 GHz | Statistical parameters and general TDL-based methodology should be revised for the THz spectrum, based on measurement campaigns or deterministic approaches, like ray tracing. |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7.3.2.2 Planar wave modeling | The far-field region is defined by the Rayleigh distance as: 2 where D is the diameter of the antenna aperture, and is the wavelength of the carrier signal. If r is larger than this distance, then an antenna beam behaves like a spherical wave and starts to diverge. Figure 27: The right half of a Gaussian bea... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7.3.2.3 Handling of large bandwidths | ETSI TR 138 901 [i.1] channel models use the carrier frequency or wavelength for channel gain and/or phase calculation. Since the fractional bandwidth and/or aperture to wavelength ratio can be larger at THz compared to the lower frequency band, it is necessary to study the need for using a sub-band-specific cent... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7.3.2.4 Lack of sensing channel modeling | ETSI TR 138 901 [i.1] channel models were designed for links between the base station and UE and lacked the sensing channel model aspects. Sensing scenarios such as monostatic or bistatic sensing channels are not modeled, which makes them unsuitable for some THz use cases. Sensing channel modeling extensions for the ET... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7.3.3 Molecular absorption | Molecular absorption may be an issue in THz bands. As it is known, the absorption coefficient depends on frequency giving the THz band a very peculiar frequency selective spectral absorption profile, such that the loss level for longer ranges can be larger since the radio waves go through more molecules. Thus, the mole... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7.3.4 Human Blockage | Human blockage has been studied extensively for millimeter-wave and sub-THz frequencies due to high attenuation and diffraction effects caused by human bodies. The shorter wavelengths at these frequencies are more susceptible to obstructions by small objects, including human bodies. To address these challenges, various... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7.3.5 Effect of THz radiation on skin | CWC University of Oulu conducted a measuring campaign to study the effect of THz radiation on human skin. Initially, pork chops were used as a proxy out of precaution, rather than using a human, for this initial experiment. The pork's skin was separated as much as possible, as shown in Figure 31. Figure 31: Pork chops ... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7.4 Propagation modelling | |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 7.4.1 Spherical wave model | Conventionally, wireless systems assume operation in the far-field region, where propagation is modeled using the plane wave theory. However, this assumption may not be accurate for modeling THz propagation in short-distance links. Given the short wavelength relative to the effective antenna aperture, part of the cover... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 8 Aspects of THz hardware interfaces | |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 8.1 ADC and DAC | Digital Converters are the bridge between the digital baseband signal domain and the analog radio frequency signal domain. Hence, the performance of data converters can be a bottleneck for the whole system. As the transmission bandwidth in THz bands can be large, the requirements for the speed of data converters increa... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 8.2 Sub-THz transceivers based on photonics | The state of the art on sub-THz transceiver architectures follows three architectures: 1) Sub-THz transmitter with an external optical modulator based on intensity modulation and a sub-THz receiver based on envelope detection. 2) Sub-THz transmitter and a sub-THz receiver architecture using direct modulation and envelo... |
e6a6c6fcc3c6d616efedf9baadd463cb | 103 952 | 8.3 Radio interface impairments | Towards experimental evaluations, previous clauses help to understand the impact of the use of radio interfaces on THz links in BCI applications. Further studies describing impairment models are as follows: a) Linear distortion is modeled by an FIR filter with a given transfer function. Power amplifiers and mixer chara... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 1 Scope | The present document analyses cryptographic schemes for selective disclosure and their potential application for privacy of electronic attestation attributes in line with the expected requirement of the proposed regulation amending Regulation (EU) No 910/2014 (commonly called eIDAS2) [i.103]. NOTE 1: The term selective... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 2 References | |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 2.1 Normative references | Normative references are not applicable in the present document. ETSI ETSI TR 119 476-1 V1.3.1 (2025-08) 22 |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 2.2 Informative references | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. NOTE: While any hyperlinks i... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 3 Definition of terms, symbols and abbreviations | |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 3.1 Terms | For the purposes of the present document, the terms given in ETSI TR 119 001 [i.91], ETSI EN 319 401 [i.89] and the following apply: atomic (Q)EAA: (Qualified) Electronic Attestation of Attribute with a single attribute claim attribute: feature, characteristic or quality of a natural or legal person or of an entity, in... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 3.2 Symbols | Void. |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 3.3 Abbreviations | For the purposes of the present document, the abbreviations given in ETSI TR 119 001 [i.91] and the following apply: 3S Secure Sub-System AA Attribute Authority ETSI ETSI TR 119 476-1 V1.3.1 (2025-08) 36 ABC Attribute Based Credentials AIR Algebraic Intermediate Representation ARF Architecture and Reference Framework A... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4 Selective disclosure signature schemes | |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.1 General | The present clause provides an analysis of a set of selective disclosure signature schemes. The topics for the analysis of each selective disclosure signature scheme are: • Underlying cryptographic algorithms for selective disclosure, unlinkability and optionally ZKP. • Maturity of the selective disclosure signature sc... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.2 Atomic (Q)EAAs schemes | An atomic Electronic Attribute Attestation is a (Q)EAA with a single attribute claim, which can be issued by a (Q)TSP upon request or as part of a batch to an EUDI Wallet. The atomic (Q)EAAs can be selected by the user and be included in a verifiable presentation that is presented to a verifier. An example of a solutio... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.3 Salted attribute hashes | |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.3.1 Overview of salted attribute hashes | Salted attribute hashes are a widely deployed concept in many solutions capable of selective disclosure. The salted hash approach computes a cryptographic digest over at least one attribute and an attribute specific random salt, e.g. a SHA256 digest over a concatenation of a salt and an attribute, SHA256 (salt||attribu... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.3.2 Issuance phase | The issuance phase of this selective disclosure scheme is in principle based on the following algorithm: 1) Parse out each attribute from a user's (Q)EAA. 2) Concatenate each attribute set with a salt, denoted as (salt||attribute). 3) Hash each (salt||attribute), denoted as hash(salt||attribute). 4) Order all the hash(... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.3.3 Presentation and verification phase | When presenting selective disclosed attributes in the (Q)EAA along with the indexed list, the relying party can perform the following verification process: 1) The EUDI Wallet parses out the disclosed attribute with key-x from the (Q)EAA. 2) The EUDI Wallet submits the disclosed (Q)EAA attribute with key-x from step 1 a... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.3.4 Salted attribute hashes and unlinkability | 4.3.4.1 General criteria of unlinkability for salted attribute hashes and associated challenges Salted-hash approaches are typically used with traditional digital signature schemes with inherent linkability risks. Issuers,verifiers, and third parties, can link disclosures and attestations through signature values or an... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.3.4.2 The Asynchronous Remote Key Generation (ARKG) algorithm | The ARKG is an abstract algorithm enabling key derivation. The specification details: 1) A generic key derivation algorithm using abstract primitives. Detailed in section 2 of [i.47], this allows for the derivation of child keys using a parent key. 2) Concrete instantiations of abstract primitives. Detailed in section ... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.3.4.3 Batch issuance and Proof of Possession / Association | Users have to be able to generate a PoP for any public key used in an attestation, including multiple single-use keys. During batch issuance, the issuer has to be certain that the public keys are associated, e.g. protected by an individual piece of secure hardware. While PoP is straightforward, PoA requires further con... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.3.5 Cryptographic analysis | The (Q)EAA and indexed hash list are separate objects that can be signed with cryptographic algorithms that are approved by SOG-IS [i.237]. In other words, there are no specific requirements on ECC curves for bilinear pairings. This concept also caters for the (Q)EAA and indexed hash list to be signed in the future wit... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.3.6 Predicates based on computational inputs | Salted attribute hashes do not inherently support dynamic calculation of predicates (e.g. to compute a proof for age over 18 given only the birth date and current date). A current approach is to include Boolean claims such as "age_over_NN": "True". However, using static age variables are problematic for several reasons... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.3.7 HashWires | |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.3.7.1 Introduction | In their 2021 paper "HashWires: Hyperefficient Credential-Based Range Proofs", Chalkias et al. [i.58] present a hash based protocol for performing inequality tests (and by extension range proofs) in contexts where a trusted issuer can sign commitments to computational inputs. The computational inputs in HashWires are a... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.3.7.2 Cryptographic analysis of HashWires | HashWires are considered as plausible quantum safe since they are based on hash chains. If the used hash functions are designed as QSC, the HashWires scheme becomes quantum-safe. Since the HashWires scheme is based on chained salted attribute hashes, it can be designed to be unlinkable for verifier(s) collusion, but is... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.3.8 Authentic Chained Data Containers (ACDCs) | Authentic Chained Data Containers (ACDCs) are verifiable data structures designed to cater for (Q)EAAs with selective disclosure requirements based on Directed Acyclic Graphs (DAGs). While a detailed account of ACDC would require describing a suite of related specifications and standards (that cover key management topi... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.3.9 Gordian Envelopes | The Gordian Envelope [i.145] is a structured format for verifiable hierarchical data. The approach relies on a graph to logically order and structure salted attributes included in an attestation. Hence, it can be used to create Directed Acyclic Graphs (DAGs) through references within or between Envelopes. Claims can be... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4 Multi-message signature schemes | |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.1 Camenisch-Lysyanskaya (CL) signatures | |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.1.1 Introduction to CL-signatures | In their paper "A signature scheme with efficient protocols" [i.42] (2002), Camenisch and Lysyanskaya introduce the CL-signature. The authors explicitly sought to design signature schemes that would be "suitable as building blocks for other applications". ETSI ETSI TR 119 476-1 V1.3.1 (2025-08) 51 Of particular relevan... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.1.2 The CL-signature scheme | CL-signatures enable the signing of messages without affecting the message's algebraic structure; a property that allows a user to prove statements about messages even if these messages are hidden in some way (e.g. using a commitment). For key generation, the first CL-scheme relies on a special RSA modulus n = pq, wher... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.1.3 The CL-signature scheme and selective disclosure | In essence, the CL-signature includes a commitment vector of messages … . The following characteristics can now be observed: • All the quadratic residues are public. • The commitment (mod n) prevents the verifier from learning m as long as solving the DLP in that group is hard. This kind of commitm... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.1.4 The CL-signature scheme, predicates, and knowledge proofs | Since the algebraic structure of the messages is preserved, it is possible to generate various proofs using CL-signatures. In their original paper, Camenisch and Lysyanskya list the following protocols known to be secure under the strong RSA assumption: • Proof of knowledge of discrete logarithm representation modulo a... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.1.5 Cryptographic analysis of the CL-signature scheme | Since the first CL-signature scheme is based on the strong RSA assumption, and later versions are based on bilinear-pairings, they are not considered as being plausible quantum-safe in a post-quantum world. The CL-signature schemes are also not possible to construct using SOG-IS approved inputs. As with BBS+ signatures... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.2 The BBS, BBS+ and BBS# signature schemes | |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.2.1 Background: Boneh-Boyen-Shacham (BBS04) signature scheme | Initially, the term group signatures was introduced in 1991 by Chaum and van Heyst in their paper "Group signatures" [i.62] as a scheme that provides anonymity for signers. This means that any member of the group can sign a message, but the resulting signature keeps the identity of the signer secret. The Stanford crypt... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.2.2 Introducing the BBS+ signature scheme | Based on the BBS04 signature scheme, the cryptographic research has continued with BBS+, which allows for multi- messages to be selectively disclosed and signed with group signatures. One major contribution was Camenisch and Lysyanskaya and their 2004 work on signature schemes and anonymous credentials from bilinear ma... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.2.3 Overview of BBS+ | The BBS+ signature scheme is illustrated in Figure 6. ETSI ETSI TR 119 476-1 V1.3.1 (2025-08) 54 Figure 6: Overview of the BBS+ signature scheme The issuer issues a (Q)EAA, with a header and a complete set of attributes, which is signed by the issuer. The (Q)EAA is stored in the user's wallet. The user selects the attr... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.2.4 IRTF CFRG BBS specification | The IRTF Crypto Forum Research Group (CFRG) has created the internet draft specification "The BBS Signature Scheme" [i.177], which specifies an internet profile of the BBS+ scheme. The specification describes the following topics: • Scheme Definition ([i.177], clause 3) defines the core operations and parameters for th... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.2.5 Device Binding Options for BBS+ | One of the core problems for the deployment of BBS+ within a reasonable amount of time seems to be the holder/device binding. Common denominator for trusted hardware (or Secure Elements) currently seems to be curve P-256 and changes to such hardware would likely take time, unless many mobile phone app manufacturers ann... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.2.6 Cryptographic analysis of the BBS+ signature scheme | In a post-quantum world, SDH algorithms based on bilinear pairings are vulnerable against quantum computing attacks [i.244]. This is an identified weakness of the BBS+ signature scheme, which has been described in a cryptographic review [i.244] prepared for the U.S. Department of Homeland Security. The report [i.244] c... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.3 The BBS# signature scheme | |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.3.1 Introduction to the BBS# protocol | BBS# [i.78] is a variant of BBS/BBS+ that has been designed to meet several stringent requirements put forth in the eIDAS 2.0. regulation. More precisely, BBS# removes the need for pairings and pairing-friendly curves (which are not standardized and not supported by trusted phone hardware) and can be combined with SOG-... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.3.2 BBS# underlying signature schemes | |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.3.2.1 General | BBS# makes use of two different types of signature schemes: on the user's side, BBS# requires (for the holder binding feature) a signature scheme that supports key blinding also known as key randomization [i.84] and [i.111] whereas on the issuer's side, a pairing-free variant of BBS, sometimes called MACBBS, is used. |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.3.2.2 Holder's signature scheme | Signatures schemes that support key blinding have the advantage that one can randomize or blind a key pair (sk, pk) to a key-pair (sk', pk') and sign a message m with the seemingly unrelated key (sk'). Of course, in the specific context of a verifiable presentation of a (Q)EEA (bound to a hardware-protected device key ... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.3.2.3 Issuer's signature scheme | The signature scheme used on the issuer's side is a pairing-free variant of BBS, called MACBBS, which, like BBS, also preserves the algebraic structure of the messages and relies on commitments. NOTE 1 : The following notation, introduced by Camenisch and Stadler [i.48] will be used in the sequel to denote a zero-knowl... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.3.3 Overview of the BBS# protocol | |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.3.3.1 General | The BBS# protocol is illustrated in Figure 6, with the addition of the holder binding public key pk in the (Q)EEA). Let sk denote the user's hardware-protected device key and = ℎ the corresponding public key. |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.3.3.2 Issuance | The issuer creates a MACBBS authentication tag σ on the user's public pk (of a signature scheme supporting key blinding / randomization) and on their attributes {} . The tag σ=(A,e) represents the user's credential and authenticates both the user's attributes and their public key pk, where: = (ℎ ℎ ⋯ ℎ... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.3.3.3 Selective disclosure | During a Verifiable Presentation (VP) of a user's attributes (or a subset of them) to the relying party (verifier), the user will first randomize their public key pk (either additively if ECSDSA is used on the user's secure cryptographic device or multiplicatively in the case of ECDSA) as well as their tag (i.e. their ... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.3.3.4 Verification | Upon receipt of = ({}∈ , , , = ( , ), ) the verifier first checks that the signature is valid, using , and then verifies the validity of the ZKP using PKI. The VP is considered valid if both verifications are successful and if the following equality = holds or n... |
2084e280c44b7014f2db1d54699ca172 | 119 476-1 | 4.4.3.4 Cryptographic analysis of the BBS# protocol | BBS#, which is proven secure in the random oracle model [i.16], retains the well-known security property (unforgeability of the credentials under the (gap) q-SDH assumption) and anonymity properties (full unlinkability and statistical anonymity of presentation proofs) of BBS/BBS+. Since BBS# is a pairing-free MMS, it r... |
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