Pub Date : 2022-06-10DOI: 10.46586/tosc.v2022.i2.161-200
Muzhou Li, N. Mouha, Ling Sun, Meiqin Wang
At EUROCRYPT ’93, Matsui introduced linear cryptanalysis. Both Matsui’s Algorithm 1 and 2 use a linear approximation involving certain state bits. Algorithm 2 requires partial encryptions or decryptions to obtain these state bits after guessing extra key bits. For ciphers where only part of the state can be obtained, like some stream ciphers and authenticated encryption schemes, Algorithm 2 will not work efficiently since it is hard to implement partial encryptions or decryptions. In this case, Algorithm 1 is a good choice since it only involves these state bits, and one bit of key information can be recovered using a single linear approximation trail. However, when there are several strong trails containing the same state bits, known as the linear hull effect, recovering key bits with Algorithm 1 is infeasible. To overcome this, Röck and Nyberg extended Matsui’s Algorithm 1 to linear hulls. However, Röck and Nyberg found that their theoretical estimates are quite pessimistic for low success probabilities and too optimistic for high success probabilities. To deal with this, we construct new statistical models where the theoretical success probabilities are in a good accordance with experimental ones, so that we provide the first accurate analysis of the extension of Matsui’s Algorithm 1 to linear hulls. To illustrate the usefulness of our new models, we apply them to one of the ten finalists of the NIST Lightweight Cryptography (LWC) Standardization project: TinyJAMBU. We provide the first cryptanalysis under the nonce-respecting setting on the full TinyJAMBU v1 and the round-reduced TinyJAMBU v2, where partial key bits are recovered. Our results do not violate the security claims made by the designers.
{"title":"Revisiting the Extension of Matsui's Algorithm 1 to Linear Hulls: Application to TinyJAMBU","authors":"Muzhou Li, N. Mouha, Ling Sun, Meiqin Wang","doi":"10.46586/tosc.v2022.i2.161-200","DOIUrl":"https://doi.org/10.46586/tosc.v2022.i2.161-200","url":null,"abstract":"At EUROCRYPT ’93, Matsui introduced linear cryptanalysis. Both Matsui’s Algorithm 1 and 2 use a linear approximation involving certain state bits. Algorithm 2 requires partial encryptions or decryptions to obtain these state bits after guessing extra key bits. For ciphers where only part of the state can be obtained, like some stream ciphers and authenticated encryption schemes, Algorithm 2 will not work efficiently since it is hard to implement partial encryptions or decryptions. In this case, Algorithm 1 is a good choice since it only involves these state bits, and one bit of key information can be recovered using a single linear approximation trail. However, when there are several strong trails containing the same state bits, known as the linear hull effect, recovering key bits with Algorithm 1 is infeasible. To overcome this, Röck and Nyberg extended Matsui’s Algorithm 1 to linear hulls. However, Röck and Nyberg found that their theoretical estimates are quite pessimistic for low success probabilities and too optimistic for high success probabilities. To deal with this, we construct new statistical models where the theoretical success probabilities are in a good accordance with experimental ones, so that we provide the first accurate analysis of the extension of Matsui’s Algorithm 1 to linear hulls. To illustrate the usefulness of our new models, we apply them to one of the ten finalists of the NIST Lightweight Cryptography (LWC) Standardization project: TinyJAMBU. We provide the first cryptanalysis under the nonce-respecting setting on the full TinyJAMBU v1 and the round-reduced TinyJAMBU v2, where partial key bits are recovered. Our results do not violate the security claims made by the designers.","PeriodicalId":37077,"journal":{"name":"IACR Transactions on Symmetric Cryptology","volume":"115 1","pages":"161-200"},"PeriodicalIF":3.5,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76801896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.46586/tosc.v2022.i2.379-414
Varun Maram, Daniel Masny, Sikhar Patranabis, Srinivasan Raghuraman
The OCB mode of operation for block ciphers has three variants, OCB1, OCB2 and OCB3. OCB1 and OCB3 can be used as secure authenticated encryption schemes whereas OCB2 has been shown to be classically insecure (Inoue et al., Crypto 2019). Even further, in the presence of quantum queries to the encryption functionality, a series of works by Kaplan et al. (Crypto 2016), Bhaumik et al. (Asiacrypt 2021) and Bonnetain et al. (Asiacrypt 2021) have shown how to break the unforgeability of the OCB modes. However, these works did not consider the confidentiality of OCB in the presence of quantum queries.We fill this gap by presenting the first formal analysis of the IND-qCPA security of OCB. In particular, we show the first attacks breaking the IND-qCPA security of the OCB modes. Surprisingly, we are able to prove that OCB2 is IND-qCPA secure when used without associated data, while relying on the assumption that the underlying block cipher is a quantum-secure pseudorandom permutation. Additionally, we present new quantum attacks breaking the universal unforgeability of OCB. Our analysis of OCB has implications for the post-quantum security of XTS, a well-known disk encryption standard, that was considered but mostly left open by Anand et al. (PQCrypto 2016).
{"title":"On the Quantum Security of OCB","authors":"Varun Maram, Daniel Masny, Sikhar Patranabis, Srinivasan Raghuraman","doi":"10.46586/tosc.v2022.i2.379-414","DOIUrl":"https://doi.org/10.46586/tosc.v2022.i2.379-414","url":null,"abstract":"The OCB mode of operation for block ciphers has three variants, OCB1, OCB2 and OCB3. OCB1 and OCB3 can be used as secure authenticated encryption schemes whereas OCB2 has been shown to be classically insecure (Inoue et al., Crypto 2019). Even further, in the presence of quantum queries to the encryption functionality, a series of works by Kaplan et al. (Crypto 2016), Bhaumik et al. (Asiacrypt 2021) and Bonnetain et al. (Asiacrypt 2021) have shown how to break the unforgeability of the OCB modes. However, these works did not consider the confidentiality of OCB in the presence of quantum queries.We fill this gap by presenting the first formal analysis of the IND-qCPA security of OCB. In particular, we show the first attacks breaking the IND-qCPA security of the OCB modes. Surprisingly, we are able to prove that OCB2 is IND-qCPA secure when used without associated data, while relying on the assumption that the underlying block cipher is a quantum-secure pseudorandom permutation. Additionally, we present new quantum attacks breaking the universal unforgeability of OCB. Our analysis of OCB has implications for the post-quantum security of XTS, a well-known disk encryption standard, that was considered but mostly left open by Anand et al. (PQCrypto 2016).","PeriodicalId":37077,"journal":{"name":"IACR Transactions on Symmetric Cryptology","volume":"28 1","pages":"379-414"},"PeriodicalIF":3.5,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83756794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.46586/tosc.v2022.i2.63-91
Jialiang Hua, Xiaoyang Dong, Siwei Sun, Zhiyu Zhang, Lei Hu, Xiaoyun Wang
At ASIACRYPT 2012, Sasaki et al. introduced the guess-and-determine approach to extend the meet-in-the-middle (MITM) preimage attack. At CRYPTO 2021, Dong et al. proposed a technique to derive the solution spaces of nonlinear constrained neutral words in the MITM preimage attack. In this paper, we try to combine these two techniques to further improve the MITM preimage attacks. Based on the previous MILP-based automatic tools for MITM attacks, we introduce new constraints due to the combination of guess-and-determine and nonlinearly constrained neutral words to build a new automatic model.As a proof of work, we apply it to the Russian national standard hash function Streebog, which is also an ISO standard. We find the first 8.5-round preimage attack on Streebog-512 compression function and the first 7.5-round preimage attack on Streebog-256 compression function. In addition, we give the 8.5-round preimage attack on Streebog-512 hash function. Our attacks extend the best previous attacks by one round. We also improve the time complexity of the 7.5-round preimage attack on Streebog-512 hash function and 6.5-round preimage attack on Streebog-256 hash function.
{"title":"Improved MITM Cryptanalysis on Streebog","authors":"Jialiang Hua, Xiaoyang Dong, Siwei Sun, Zhiyu Zhang, Lei Hu, Xiaoyun Wang","doi":"10.46586/tosc.v2022.i2.63-91","DOIUrl":"https://doi.org/10.46586/tosc.v2022.i2.63-91","url":null,"abstract":"At ASIACRYPT 2012, Sasaki et al. introduced the guess-and-determine approach to extend the meet-in-the-middle (MITM) preimage attack. At CRYPTO 2021, Dong et al. proposed a technique to derive the solution spaces of nonlinear constrained neutral words in the MITM preimage attack. In this paper, we try to combine these two techniques to further improve the MITM preimage attacks. Based on the previous MILP-based automatic tools for MITM attacks, we introduce new constraints due to the combination of guess-and-determine and nonlinearly constrained neutral words to build a new automatic model.As a proof of work, we apply it to the Russian national standard hash function Streebog, which is also an ISO standard. We find the first 8.5-round preimage attack on Streebog-512 compression function and the first 7.5-round preimage attack on Streebog-256 compression function. In addition, we give the 8.5-round preimage attack on Streebog-512 hash function. Our attacks extend the best previous attacks by one round. We also improve the time complexity of the 7.5-round preimage attack on Streebog-512 hash function and 6.5-round preimage attack on Streebog-256 hash function.","PeriodicalId":37077,"journal":{"name":"IACR Transactions on Symmetric Cryptology","volume":"19 1","pages":"63-91"},"PeriodicalIF":3.5,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89619740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.46586/tosc.v2022.i2.141-160
T. Beyne, Yunwen Liu
We improve truncated differential attacks on t-branch contracting Feistel ciphers with a domain size of Nt. Based on new truncated differentials, a generic distinguisher for t2 + t − 2 rounds using O(Nt−1) data and time is obtained. In addition, we obtain a key-recovery attack on t2 + 1 rounds with Õ(Nt−2) data and Õ(Nt−1) time. Compared to previous results by Guo et al. (ToSC 2016), our attacks cover more rounds with a lower data-complexity. Applications of the generic truncated differential to concrete ciphers include full-round attacks on some instances of GMiMC-crf, and the best-known key-recovery attack on 17 rounds of the Chinese block cipher standard SM4. In addition, we propose an automated search method for truncated differentials using SMT, which is effective even for trails with probability below the probability of the truncated differential for a random permutation.
{"title":"Truncated Differential Attacks on Contracting Feistel Ciphers","authors":"T. Beyne, Yunwen Liu","doi":"10.46586/tosc.v2022.i2.141-160","DOIUrl":"https://doi.org/10.46586/tosc.v2022.i2.141-160","url":null,"abstract":"We improve truncated differential attacks on t-branch contracting Feistel ciphers with a domain size of Nt. Based on new truncated differentials, a generic distinguisher for t2 + t − 2 rounds using O(Nt−1) data and time is obtained. In addition, we obtain a key-recovery attack on t2 + 1 rounds with Õ(Nt−2) data and Õ(Nt−1) time. Compared to previous results by Guo et al. (ToSC 2016), our attacks cover more rounds with a lower data-complexity. Applications of the generic truncated differential to concrete ciphers include full-round attacks on some instances of GMiMC-crf, and the best-known key-recovery attack on 17 rounds of the Chinese block cipher standard SM4. In addition, we propose an automated search method for truncated differentials using SMT, which is effective even for trails with probability below the probability of the truncated differential for a random permutation.","PeriodicalId":37077,"journal":{"name":"IACR Transactions on Symmetric Cryptology","volume":"25 1","pages":"141-160"},"PeriodicalIF":3.5,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79278011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.46586/tosc.v2022.i2.113-140
Virginie Lallemand, M. Minier, Loïc Rouquette
In this paper we present a boomerang analysis of WARP, a recently proposed Generalized Feistel Network with extremely compact hardware implementations. We start by looking for boomerang characteristics that directly take into account the boomerang switch effects by showing how to adapt Delaune et al. automated tool to the case of Feistel ciphers, and discuss several improvements to keep the execution time reasonable. This technique returns a 23-round distinguisher of probability 2−124, which becomes the best distinguisher presented on WARP so far. We then look for an attack by adding the key recovery phase to our model and we obtain a 26-round rectangle attack with time and data complexities of 2115.9 and 2120.6 respectively, again resulting in the best result presented so far. Incidentally, our analysis discloses how an attacker can take advantage of the position of the key addition (put after the S-box application to avoid complementation properties), which in our case offers an improvement of a factor of 275 of the time complexity in comparison to a variant with the key addition positioned before. Note that our findings do not threaten the security of the cipher which iterates 41 rounds.
{"title":"Automatic Search of Rectangle Attacks on Feistel Ciphers: Application to WARP","authors":"Virginie Lallemand, M. Minier, Loïc Rouquette","doi":"10.46586/tosc.v2022.i2.113-140","DOIUrl":"https://doi.org/10.46586/tosc.v2022.i2.113-140","url":null,"abstract":"In this paper we present a boomerang analysis of WARP, a recently proposed Generalized Feistel Network with extremely compact hardware implementations. We start by looking for boomerang characteristics that directly take into account the boomerang switch effects by showing how to adapt Delaune et al. automated tool to the case of Feistel ciphers, and discuss several improvements to keep the execution time reasonable. This technique returns a 23-round distinguisher of probability 2−124, which becomes the best distinguisher presented on WARP so far. We then look for an attack by adding the key recovery phase to our model and we obtain a 26-round rectangle attack with time and data complexities of 2115.9 and 2120.6 respectively, again resulting in the best result presented so far. Incidentally, our analysis discloses how an attacker can take advantage of the position of the key addition (put after the S-box application to avoid complementation properties), which in our case offers an improvement of a factor of 275 of the time complexity in comparison to a variant with the key addition positioned before. Note that our findings do not threaten the security of the cipher which iterates 41 rounds.","PeriodicalId":37077,"journal":{"name":"IACR Transactions on Symmetric Cryptology","volume":"18 1","pages":"113-140"},"PeriodicalIF":3.5,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88218598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.46586/tosc.v2022.i2.43-62
N. Bardeh, V. Rijmen
A new fundamental 4-round property of AES, called the zero-difference property, was introduced by Rønjom, Bardeh and Helleseth at Asiacrypt 2017. Our work characterizes it in a simple way by exploiting the notion of related differences which was introduced and well analyzed by the AES designers. We extend the 4-round property by considering some further properties of related differences over the AES linear layer, generalizing the zero-difference property. This results in a new key-recovery attack on 7-round AES which is the first attack on 7-round AES by exploiting the zero-difference property.
{"title":"New Key Recovery Attack on Reduced-Round AES","authors":"N. Bardeh, V. Rijmen","doi":"10.46586/tosc.v2022.i2.43-62","DOIUrl":"https://doi.org/10.46586/tosc.v2022.i2.43-62","url":null,"abstract":"A new fundamental 4-round property of AES, called the zero-difference property, was introduced by Rønjom, Bardeh and Helleseth at Asiacrypt 2017. Our work characterizes it in a simple way by exploiting the notion of related differences which was introduced and well analyzed by the AES designers. We extend the 4-round property by considering some further properties of related differences over the AES linear layer, generalizing the zero-difference property. This results in a new key-recovery attack on 7-round AES which is the first attack on 7-round AES by exploiting the zero-difference property.","PeriodicalId":37077,"journal":{"name":"IACR Transactions on Symmetric Cryptology","volume":"3 1","pages":"43-62"},"PeriodicalIF":3.5,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87562106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.46586/tosc.v2022.i2.253-288
Alireza Mehrdad, S. Mella, Lorenzo Grassi, J. Daemen
Proving upper bounds for the expected differential probability (DP) of differential trails is a standard requirement when proposing a new symmetric primitive. In the case of cryptographic primitives with a bit-oriented round function, such as Keccak, Xoodoo and Subterranean, computer assistance is required in order to prove strong upper bounds on the probability of differential trails. The techniques described in the literature make use of the fact that the non-linear step of the round function is an S-box layer. In the case of Keccak and Xoodoo, the S-boxes are instances of the chi mapping operating on l-bit circles with l equal to 5 and 3 respectively. In that case the differential propagation properties of the non-linear layer can be evaluated efficiently by the use of pre-computed difference distribution tables.Subterranean 2.0 is a recently proposed cipher suite that has exceptionally good energy-efficiency when implemented in hardware (ASIC and FPGA). The non-linear step of its round function is also based on the chi mapping, but operating on an l = 257-bit circle, comprising all the state bits. This making the brute-force approach proposed and used for Keccak and Xoodoo infeasible to apply. Difference propagation through the chi mapping from input to output can be treated using linear algebra thanks to the fact that chi has algebraic degree 2. However, difference propagation from output to input is problematic for big-circle chi. In this paper, we tackle this problem, and present new techniques for the analysis of difference propagation for big-circle chi.We implemented these techniques in a dedicated program to perform differential trail search in Subterranean. Thanks to this, we confirm the maximum DP of 3-round trails found by the designers, we determine the maximum DP of 4-round trails and we improve the upper bounds for the DP of trails over 5, 6, 7 and 8 rounds.
{"title":"Differential Trail Search in Cryptographic Primitives with Big-Circle Chi: Application to Subterranean","authors":"Alireza Mehrdad, S. Mella, Lorenzo Grassi, J. Daemen","doi":"10.46586/tosc.v2022.i2.253-288","DOIUrl":"https://doi.org/10.46586/tosc.v2022.i2.253-288","url":null,"abstract":"Proving upper bounds for the expected differential probability (DP) of differential trails is a standard requirement when proposing a new symmetric primitive. In the case of cryptographic primitives with a bit-oriented round function, such as Keccak, Xoodoo and Subterranean, computer assistance is required in order to prove strong upper bounds on the probability of differential trails. The techniques described in the literature make use of the fact that the non-linear step of the round function is an S-box layer. In the case of Keccak and Xoodoo, the S-boxes are instances of the chi mapping operating on l-bit circles with l equal to 5 and 3 respectively. In that case the differential propagation properties of the non-linear layer can be evaluated efficiently by the use of pre-computed difference distribution tables.Subterranean 2.0 is a recently proposed cipher suite that has exceptionally good energy-efficiency when implemented in hardware (ASIC and FPGA). The non-linear step of its round function is also based on the chi mapping, but operating on an l = 257-bit circle, comprising all the state bits. This making the brute-force approach proposed and used for Keccak and Xoodoo infeasible to apply. Difference propagation through the chi mapping from input to output can be treated using linear algebra thanks to the fact that chi has algebraic degree 2. However, difference propagation from output to input is problematic for big-circle chi. In this paper, we tackle this problem, and present new techniques for the analysis of difference propagation for big-circle chi.We implemented these techniques in a dedicated program to perform differential trail search in Subterranean. Thanks to this, we confirm the maximum DP of 3-round trails found by the designers, we determine the maximum DP of 4-round trails and we improve the upper bounds for the DP of trails over 5, 6, 7 and 8 rounds.","PeriodicalId":37077,"journal":{"name":"IACR Transactions on Symmetric Cryptology","volume":"3 1","pages":"253-288"},"PeriodicalIF":3.5,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81217746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-11DOI: 10.46586/tosc.v2022.i1.1-4
Itai Dinur, Bart Mennink
IACR Transactions on Symmetric Cryptology (ToSC) is a forum for original results in all areas of symmetric cryptography, including the design and analysis of block ciphers, stream ciphers, encryption schemes, hash functions, message authentication codes, (cryptographic) permutations, authenticated encryption schemes, cryptanalysis and evaluation tools, and security issues and solutions regarding their implementation. ToSC implements an open-access journal/conference hybrid model following some other communities in computer science. All articles undergo a journal-style reviewing process and accepted papers are published in gold open access (in our case the Creative Commons License CC-BY 4.0). The review procedures that we have followed strictly adhere to the traditions of the journal world. The ToSC review process strives to maintain a high quality of published articles. Full papers are assigned to at least three members of the Editorial Board; for submissions by Editorial Board members this was increased to at least four. These members write detailed and careful reviews (usually without relying on subreviewers). Moreover, we have had a rebuttal phase, allowing authors to respond to the review comments before the final decisions. If necessary, the review process enables further interactions between the authors and the reviewers, mediated by the Co-Editors-in-Chief. The Editorial Board can also decide to ask for a minor or major revision of the paper when changes are deemed necessary to improve its quality. Furthermore, the Editorial Board can give a “reject and resubmit” decision in case a submission is considered to have potential, but there are significant issues to address before it can be properly evaluated. Next to regular submissions, ToSC also accepts submissions of addendum and errata papers. Addendum papers aim at extending an existing ToSC paper in a novel, yet succinct way. Errata papers aim at correcting an error in an existing ToSC paper. Overall, we are very pleased with the quality and quantity of submissions, the detailed review reports written by the reviewers and the substantial efforts by the authors to further improve the quality of their work. We think that the review process, and in particular the use of major revisions, leads to an increased quality of the papers that are published. The papers selected by the Editorial Board for publication are presented at the conference Fast Software Encryption (FSE). This gives the authors the opportunity to advertize their results and engage in discussions on further work. In 2022, FSE was held during March 20-25, 2022 in Athens, Greece. However, due to the COVID-19 pandemic, the conference was organized in a different way than usual. Most importantly, the conference was held in a hybrid format, accommodating both in-person and online participation. In addition, as FSE 2021 was cancelled, part of the papers originally scheduled for FSE 2021 were postponed to FSE 2022. In detail, papers f
{"title":"Preface to Volume 2022, Issue 1","authors":"Itai Dinur, Bart Mennink","doi":"10.46586/tosc.v2022.i1.1-4","DOIUrl":"https://doi.org/10.46586/tosc.v2022.i1.1-4","url":null,"abstract":"IACR Transactions on Symmetric Cryptology (ToSC) is a forum for original results in all areas of symmetric cryptography, including the design and analysis of block ciphers, stream ciphers, encryption schemes, hash functions, message authentication codes, (cryptographic) permutations, authenticated encryption schemes, cryptanalysis and evaluation tools, and security issues and solutions regarding their implementation. ToSC implements an open-access journal/conference hybrid model following some other communities in computer science. All articles undergo a journal-style reviewing process and accepted papers are published in gold open access (in our case the Creative Commons License CC-BY 4.0). The review procedures that we have followed strictly adhere to the traditions of the journal world. The ToSC review process strives to maintain a high quality of published articles. Full papers are assigned to at least three members of the Editorial Board; for submissions by Editorial Board members this was increased to at least four. These members write detailed and careful reviews (usually without relying on subreviewers). Moreover, we have had a rebuttal phase, allowing authors to respond to the review comments before the final decisions. If necessary, the review process enables further interactions between the authors and the reviewers, mediated by the Co-Editors-in-Chief. The Editorial Board can also decide to ask for a minor or major revision of the paper when changes are deemed necessary to improve its quality. Furthermore, the Editorial Board can give a “reject and resubmit” decision in case a submission is considered to have potential, but there are significant issues to address before it can be properly evaluated. Next to regular submissions, ToSC also accepts submissions of addendum and errata papers. Addendum papers aim at extending an existing ToSC paper in a novel, yet succinct way. Errata papers aim at correcting an error in an existing ToSC paper. Overall, we are very pleased with the quality and quantity of submissions, the detailed review reports written by the reviewers and the substantial efforts by the authors to further improve the quality of their work. We think that the review process, and in particular the use of major revisions, leads to an increased quality of the papers that are published. The papers selected by the Editorial Board for publication are presented at the conference Fast Software Encryption (FSE). This gives the authors the opportunity to advertize their results and engage in discussions on further work. In 2022, FSE was held during March 20-25, 2022 in Athens, Greece. However, due to the COVID-19 pandemic, the conference was organized in a different way than usual. Most importantly, the conference was held in a hybrid format, accommodating both in-person and online participation. In addition, as FSE 2021 was cancelled, part of the papers originally scheduled for FSE 2021 were postponed to FSE 2022. In detail, papers f","PeriodicalId":37077,"journal":{"name":"IACR Transactions on Symmetric Cryptology","volume":"22 1","pages":"1-4"},"PeriodicalIF":3.5,"publicationDate":"2022-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84857842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-11DOI: 10.46586/tosc.v2022.i1.110-137
C. Cid, Lorenzo Grassi, Aldo Gunsing, Reinhard Lüftenegger, Christian Rechberger, Markus Schofnegger
We consider SPN schemes, i.e., schemes whose non-linear layer is defined as the parallel application of t ≥ 1 independent S-Boxes over F2n and whose linear layer is defined by the multiplication with a (n · t) × (n · t) matrix over F2. Even if the algebraic representation of a scheme depends on all its components, upper bounds on the growth of the algebraic degree in the literature usually only consider the details of the non-linear layer. Hence a natural question arises: (how) do the details of the linear layer influence the growth of the algebraic degree? We show that the linear layer plays a crucial role in the growth of the algebraic degree and present a new upper bound on the algebraic degree in SP-networks. As main results, we prove that in the case of low-degree round functions with large S-Boxes: (a) an initial exponential growth of the algebraic degree can be followed by a linear growth until the maximum algebraic degree is reached; (b) the rate of the linear growth is proportional to the degree of the linear layer over Ft2n. Besides providing a theoretical insight, our analysis is particularly relevant for assessing the security of the security of cryptographic permutations designed to be competitive in applications like MPC, FHE, SNARKs, and STARKs, including permutations based on the Hades design strategy. We have verified our findings on small-scale instances and we have compared them against the currently best results in the literature, showing a substantial improvement of upper bounds on the algebraic degree in case of low-degree round functions with large S-Boxes.
{"title":"Influence of the Linear Layer on the Algebraic Degree in SP-Networks","authors":"C. Cid, Lorenzo Grassi, Aldo Gunsing, Reinhard Lüftenegger, Christian Rechberger, Markus Schofnegger","doi":"10.46586/tosc.v2022.i1.110-137","DOIUrl":"https://doi.org/10.46586/tosc.v2022.i1.110-137","url":null,"abstract":"We consider SPN schemes, i.e., schemes whose non-linear layer is defined as the parallel application of t ≥ 1 independent S-Boxes over F2n and whose linear layer is defined by the multiplication with a (n · t) × (n · t) matrix over F2. Even if the algebraic representation of a scheme depends on all its components, upper bounds on the growth of the algebraic degree in the literature usually only consider the details of the non-linear layer. Hence a natural question arises: (how) do the details of the linear layer influence the growth of the algebraic degree? We show that the linear layer plays a crucial role in the growth of the algebraic degree and present a new upper bound on the algebraic degree in SP-networks. As main results, we prove that in the case of low-degree round functions with large S-Boxes: (a) an initial exponential growth of the algebraic degree can be followed by a linear growth until the maximum algebraic degree is reached; (b) the rate of the linear growth is proportional to the degree of the linear layer over Ft2n. Besides providing a theoretical insight, our analysis is particularly relevant for assessing the security of the security of cryptographic permutations designed to be competitive in applications like MPC, FHE, SNARKs, and STARKs, including permutations based on the Hades design strategy. We have verified our findings on small-scale instances and we have compared them against the currently best results in the literature, showing a substantial improvement of upper bounds on the algebraic degree in case of low-degree round functions with large S-Boxes.","PeriodicalId":37077,"journal":{"name":"IACR Transactions on Symmetric Cryptology","volume":"21 1","pages":"110-137"},"PeriodicalIF":3.5,"publicationDate":"2022-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86977665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-11DOI: 10.46586/tosc.v2022.i1.38-63
G. Leander, Shahram Rasoolzadeh
CRAFT is a lightweight tweakable Substitution-Permutation-Network (SPN) block cipher optimized for efficient protection of its implementations against Differential Fault Analysis (DFA) attacks. In this paper, we present an equivalent description of CRAFT up to a simple mapping on the plaintext, ciphertext and round tweakeys. We show that the new representation, for a sub-class of keys, leads to a new structure which is a Feistel network, with non-linear operation and key addition only on half the state. Consequently, it reveals a class of weak keys for which CRAFT is less resistant against differential and linear cryptanalyses. As a result, we present one weak-key single-tweak differential attack on 23 rounds (with time complexity of 294 encryptions and data complexity of 274 chosen plaintext/tweak/ciphertext tuples and works for 2112 weak keys) and one weak-key related-tweak attack on 26 rounds of the cipher (with time complexity of 2105 encryptions and data complexity 273 chosen plaintext/tweak/ciphertext tuples and works for 2108 weak keys). Note that these attacks do not break the security claim of the CRAFT block cipher.
{"title":"Weak Tweak-Keys for the CRAFT Block Cipher","authors":"G. Leander, Shahram Rasoolzadeh","doi":"10.46586/tosc.v2022.i1.38-63","DOIUrl":"https://doi.org/10.46586/tosc.v2022.i1.38-63","url":null,"abstract":"CRAFT is a lightweight tweakable Substitution-Permutation-Network (SPN) block cipher optimized for efficient protection of its implementations against Differential Fault Analysis (DFA) attacks. In this paper, we present an equivalent description of CRAFT up to a simple mapping on the plaintext, ciphertext and round tweakeys. We show that the new representation, for a sub-class of keys, leads to a new structure which is a Feistel network, with non-linear operation and key addition only on half the state. Consequently, it reveals a class of weak keys for which CRAFT is less resistant against differential and linear cryptanalyses. As a result, we present one weak-key single-tweak differential attack on 23 rounds (with time complexity of 294 encryptions and data complexity of 274 chosen plaintext/tweak/ciphertext tuples and works for 2112 weak keys) and one weak-key related-tweak attack on 26 rounds of the cipher (with time complexity of 2105 encryptions and data complexity 273 chosen plaintext/tweak/ciphertext tuples and works for 2108 weak keys). Note that these attacks do not break the security claim of the CRAFT block cipher.","PeriodicalId":37077,"journal":{"name":"IACR Transactions on Symmetric Cryptology","volume":"13 1","pages":"38-63"},"PeriodicalIF":3.5,"publicationDate":"2022-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81922395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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