scholarly journals The Area-Latency Symbiosis: Towards Improved Serial Encryption Circuits

2020 ◽  
pp. 239-278
Author(s):  
Fatih Balli ◽  
Andrea Caforio ◽  
Subhadeep Banik
Keyword(s):  
Block Cipher ◽  
Block Ciphers ◽  
Significant Loss ◽  
Authenticated Encryption ◽  
End User ◽  
Maximum Throughput ◽  
Mode Of Operation ◽  
Encryption Schemes ◽  
Bit Serial

The bit-sliding paper of Jean et al. (CHES 2017) showed that the smallest-size circuit for SPN based block ciphers such as AES, SKINNY and PRESENT can be achieved via bit-serial implementations. Their technique decreases the bit size of the datapath and naturally leads to a significant loss in latency (as well as the maximum throughput). Their designs complete a single round of the encryption in 168 (resp. 68) clock cycles for 128 (resp. 64) bit blocks. A follow-up work by Banik et al. (FSE 2020) introduced the swap-and-rotate technique that both eliminates this loss in latency and achieves even smaller footprints.In this paper, we extend these results on bit-serial implementations all the way to four authenticated encryption schemes from NIST LWC. Our first focus is to decrease latency and improve throughput with the use of the swap-and-rotate technique. Our block cipher implementations have the most efficient round operations in the sense that a round function of an n-bit block cipher is computed in exactly n clock cycles. This leads to implementations that are similar in size to the state of the art, but have much lower latency (savings up to 20 percent). We then extend our technique to 4- and 8-bit implementations. Although these results are promising, block ciphers themselves are not end-user primitives, as they need to be used in conjunction with a mode of operation. Hence, in the second part of the paper, we use our serial block ciphers to bootstrap four active NIST authenticated encryption candidates: SUNDAE-GIFT, Romulus, SAEAES and SKINNY-AEAD. In the wake of this effort, we provide the smallest block-cipher-based authenticated encryption circuits known in the literature so far.

scholarly journals Six shades lighter: a bit-serial implementation of the AES family

2021 ◽  
Author(s):  
Sergio Roldán Lombardía ◽  
Fatih Balli ◽  
Subhadeep Banik
Keyword(s):  
Block Cipher ◽  
Block Ciphers ◽  
Authenticated Encryption ◽  
Current Standard ◽  
Asic Circuit ◽  
The Family ◽  
Encryption And Decryption ◽  
Preliminary Version ◽  
Reduction In Area ◽  
Bit Serial

AbstractRecently, cryptographic literature has seen new block cipher designs such as , or that aim to be more lightweight than the current standard, i.e., . Even though family of block ciphers were designed two decades ago, they still remain as the de facto encryption standard, with being the most widely deployed variant. In this work, we revisit the combined one-in-all implementation of the family, namely both encryption and decryption of each as a single ASIC circuit. A preliminary version appeared in Africacrypt 2019 by Balli and Banik, where the authors design a byte-serial circuit with such functionality. We improve on their work by reducing the size of the compact circuit to 2268 GE through 1-bit-serial implementation, which achieves 38% reduction in area. We also report stand-alone bit-serial versions of the circuit, targeting only a subset of modes and versions, e.g., and . Our results imply that, in terms of area, and can easily compete with the larger members of recently designed family, e.g., , . Thus, our implementations can be used interchangeably inside authenticated encryption candidates such as , or in place of .

scholarly journals Efficient Length Doubling From Tweakable Block Ciphers

2017 ◽  
pp. 253-270 ◽  
Author(s):  
Yu Long Chen ◽  
Atul Luykx ◽  
Bart Mennink ◽  
Bart Preneel
Keyword(s):  
Block Cipher ◽  
Block Ciphers ◽  
Encryption Scheme ◽  
Authenticated Encryption ◽  
Arbitrary Length ◽  
Pseudorandom Permutation ◽  
Cryptographic Primitive ◽  
Length Data ◽  
Tweakable Block Cipher ◽  
Integral Data

We present a length doubler, LDT, that turns an n-bit tweakable block cipher into an efficient and secure cipher that can encrypt any bit string of length [n..2n − 1]. The LDT mode is simple, uses only two cryptographic primitive calls (while prior work needs at least four), and is a strong length-preserving pseudorandom permutation if the underlying tweakable block ciphers are strong tweakable pseudorandom permutations. We demonstrate that LDT can be used to neatly turn an authenticated encryption scheme for integral data into a mode for arbitrary-length data.

scholarly journals A fundamental flaw in the ++AE authenticated encryption mode

2018 ◽  
Vol 12 (1) ◽  
pp. 37-42
Author(s):  
Hassan Qahur Al Mahri ◽  
Leonie Simpson ◽  
Harry Bartlett ◽  
Ed Dawson ◽  
Kenneth Koon-Ho Wong
Keyword(s):  
Block Cipher ◽  
Authenticated Encryption ◽  
Forgery Attack ◽  
Mathematical Proofs ◽  
Mode Of Operation ◽  
Public Message ◽  
Integrity Check

Abstract In this article, we analyse a block cipher mode of operation for authenticated encryption known as ++AE (plus-plus-AE). We show that this mode has a fundamental flaw: the scheme does not verify the most significant bit of any block in the plaintext message. This flaw can be exploited by choosing a plaintext message and then constructing multiple forged messages in which the most significant bit of certain blocks is flipped. All of these plaintext messages will generate the same authentication tag. This forgery attack is deterministic and guaranteed to pass the ++AE integrity check. The success of the attack is independent of the underlying block cipher, key or public message number. We outline the mathematical proofs for the flaw in the ++AE algorithm. We conclude that ++AE is insecure as an authenticated encryption mode of operation.

Improved Meet-in-the-Middle Attacks on Reduced-Round Kiasu-BC and Joltik-BC

2019 ◽  
Vol 62 (12) ◽  
pp. 1761-1776 ◽  
Author(s):  
Ya Liu ◽  
Yifan Shi ◽  
Dawu Gu ◽  
Zhiqiang Zeng ◽  
Fengyu Zhao ◽  
...  
Keyword(s):  
Block Cipher ◽  
Block Ciphers ◽  
Authenticated Encryption ◽  
Caesar Competition ◽  
Encryption Algorithms ◽  
Lightweight Block Cipher

Abstract Kiasu-BC and Joltik-BC are internal tweakable block ciphers of authenticated encryption algorithms Kiasu and Joltik submitted to the CAESAR competition. Kiasu-BC is a 128-bit block cipher, of which tweak and key sizes are 64 and 128 bits, respectively. Joltik-BC-128 is a 64-bit lightweight block cipher supporting 128 bits tweakey. Its designers recommended the key and tweak sizes are both 64 bits. In this paper, we propose improved meet-in-the-middle attacks on 8-round Kiasu-BC, 9-round and 10-round Joltik-BC-128 by exploiting properties of their structures and using precomputation tables and the differential enumeration. For Kiasu-BC, we build a 5-round distinguisher to attack 8-round Kiasu-BC with $2^{109}$ plaintext–tweaks, $2^{112.8}$ encrytions and $2^{92.91}$ blocks. Compared with previously best known cryptanalytic results on 8-round Kiasu-BC under chosen plaintext attacks, the data and time complexities are reduced by $2^{7}$ and $2^{3.2}$ times, respectively. For the recommended version of Joltik-BC-128, we construct a 6-round distinguisher to attack 9-round Joltik-BC-128 with $2^{53}$ plaintext–tweaks, $2^{56.6}$ encryptions and $2^{52.91}$ blocks, respectively. Compared with previously best known results, the data and time complexities are reduced by $2^7$ and $2^{5.1}$ times, respectively. In addition, we present a 6.5-round distinguisher to attack 10-round Joltik-BC-128 with $2^{53}$ plaintext–tweaks, $2^{101.4}$ encryptions and $2^{76.91}$ blocks.

scholarly journals A Security Analysis of Deoxys and its Internal Tweakable Block Ciphers

2017 ◽  
pp. 73-107 ◽  
Author(s):  
Carlos Cid ◽  
Tao Huang ◽  
Thomas Peyrin ◽  
Yu Sasaki ◽  
Ling Song
Keyword(s):  
Linear Programming ◽  
Mixed Integer Linear Programming ◽  
Block Cipher ◽  
Security Analysis ◽  
Block Ciphers ◽  
Mixed Integer ◽  
Authenticated Encryption ◽  
Search Tool ◽  
Caesar Competition ◽  
Milp Model

In this article, we provide the first independent security analysis of Deoxys, a third-round authenticated encryption candidate of the CAESAR competition, and its internal tweakable block ciphers Deoxys-BC-256 and Deoxys-BC-384. We show that the related-tweakey differential bounds provided by the designers can be greatly improved thanks to a Mixed Integer Linear Programming (MILP) based search tool. In particular, we develop a new method to incorporate linear incompatibility in the MILP model. We use this tool to generate valid differential paths for reduced-round versions of Deoxys-BC-256 and Deoxys-BC-384, later combining them into broader boomerang or rectangle attacks. Here, we also develop a new MILP model which optimises the two paths by taking into account the effect of the ladder switch technique. Interestingly, with the tweak in Deoxys-BC providing extra input as opposed to a classical block cipher, we can even consider beyond full-codebook attacks. As these primitives are based on the TWEAKEY framework, we further study how the security of the cipher is impacted when playing with the tweak/key sizes. All in all, we are able to attack 10 rounds of Deoxys-BC-256 (out of 14) and 13 rounds of Deoxys-BC-384 (out of 16). The extra rounds specified in Deoxys-BC to balance the tweak input (when compared to AES) seem to provide about the same security margin as AES-128. Finally we analyse why the authenticated encryption modes of Deoxys mostly prevent our attacks on Deoxys-BC to apply to the authenticated encryption primitive.

scholarly journals Hardware Performance Evaluation of Authenticated Encryption SAEAES with Threshold Implementation

Cryptography ◽  
2020 ◽  
Vol 4 (3) ◽  
pp. 23
Author(s):  
Takeshi Sugawara
Keyword(s):  
Block Cipher ◽  
Authenticated Encryption ◽  
Lightweight Cryptography ◽  
Key Schedule ◽  
Backward Compatibility ◽  
Mode Of Operation ◽  
Large Memory ◽  
Extended States ◽  
Lightweight Block Cipher ◽  
The Cost

SAEAES is the authenticated encryption algorithm instantiated by combining the SAEB mode of operation with AES, and a candidate of the NIST’s lightweight cryptography competition. Using AES gives the advantage of backward compatibility with the existing accelerators and coprocessors that the industry has invested in so far. Still, the newer lightweight block cipher (e.g., GIFT) outperforms AES in compact implementation, especially with the side-channel attack countermeasure such as threshold implementation. This paper aims to implement the first threshold implementation of SAEAES and evaluate the cost we are trading with the backward compatibility. We design a new circuit architecture using the column-oriented serialization based on the recent 3-share and uniform threshold implementation (TI) of the AES S-box based on the generalized changing of the guards. Our design uses 18,288 GE with AES’s occupation reaching 97% of the total area. Meanwhile, the circuit area is roughly three times the conventional SAEB-GIFT implementation (6229 GE) because of a large memory size needed for the AES’s non-linear key schedule and the extended states for satisfying uniformity in TI.

scholarly journals Close to Optimally Secure Variants of GCM

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Ping Zhang ◽  
Hong-Gang Hu ◽  
Qian Yuan
Keyword(s):  
Block Cipher ◽  
Positive Response ◽  
Block Size ◽  
Hybrid Technique ◽  
Authenticated Encryption ◽  
Pseudorandom Functions ◽  
Pseudorandom Permutation ◽  
Mode Of Operation ◽  
Universal Hash Function ◽  
Provably Secure

The Galois/Counter Mode of operation (GCM) is a widely used nonce-based authenticated encryption with associated data mode which provides the birthday-bound security in the nonce-respecting scenario; that is, it is secure up to about 2n/2 adversarial queries if all nonces used in the encryption oracle are never repeated, where n is the block size. It is an open problem to analyze whether GCM security can be improved by using some simple operations. This paper presents a positive response for this problem. Firstly, we introduce two close to optimally secure pseudorandom functions and derive their security bound by the hybrid technique. Then, we utilize these pseudorandom functions that we design and a universal hash function to construct two improved versions of GCM, called OGCM-1 and OGCM-2. OGCM-1 and OGCM-2 are, respectively, provably secure up to approximately 2n/67(n-1)2 and 2n/67 adversarial queries in the nonce-respecting scenario if the underlying block cipher is a secure pseudorandom permutation. Finally, we discuss the properties of OGCM-1 and OGCM-2 and describe the future works.

scholarly journals Spook: Sponge-Based Leakage-Resistant Authenticated Encryption with a Masked Tweakable Block Cipher

2020 ◽  
pp. 295-349 ◽  
Author(s):  
Davide Bellizia ◽  
Francesco Berti ◽  
Olivier Bronchain ◽  
Gaëtan Cassiers ◽  
Sébastien Duval ◽  
...  
Keyword(s):  
Block Cipher ◽  
Block Size ◽  
Minimum Cost ◽  
Side Channel ◽  
Authenticated Encryption ◽  
Side Channel Attacks ◽  
Mode Of Operation ◽  
Channel Analysis ◽  
Tweakable Block Cipher ◽  
Software And Hardware

This paper defines Spook: a sponge-based authenticated encryption with associated data algorithm. It is primarily designed to provide security against side-channel attacks at a low energy cost. For this purpose, Spook is mixing a leakageresistant mode of operation with bitslice ciphers enabling efficient and low latency implementations. The leakage-resistant mode of operation leverages a re-keying function to prevent differential side-channel analysis, a duplex sponge construction to efficiently process the data, and a tag verification based on a Tweakable Block Cipher (TBC) providing strong data integrity guarantees in the presence of leakages. The underlying bitslice ciphers are optimized for the masking countermeasures against side-channel attacks. Spook is an efficient single-pass algorithm. It ensures state-of-the-art black box security with several prominent features: (i) nonce misuse-resilience, (ii) beyond-birthday security with respect to the TBC block size, and (iii) multiuser security at minimum cost with a public tweak. Besides the specifications and design rationale, we provide first software and hardware implementation results of (unprotected) Spook which confirm the limited overheads that the use of two primitives sharing internal components imply. We also show that the integrity of Spook with leakage, so far analyzed with unbounded leakages for the duplex sponge and a strongly protected TBC modeled as leak-free, can be proven with a much weaker unpredictability assumption for the TBC. We finally discuss external cryptanalysis results and tweaks to improve both the security margins and efficiency of Spook.

scholarly journals SKINNY-AEAD and SKINNY-Hash

2020 ◽  
pp. 88-131 ◽  
Author(s):  
Christof Beierle ◽  
Jérémy Jean ◽  
Stefan Kölbl ◽  
Gregor Leander ◽  
Amir Moradi ◽  
...  
Keyword(s):  
Internal State ◽  
Block Ciphers ◽  
Third Party ◽  
Authenticated Encryption ◽  
Lightweight Cryptography ◽  
The Family ◽  
Encryption Schemes ◽  
Standardization Process

We present the family of authenticated encryption schemes SKINNY-AEAD and the family of hashing schemes SKINNY-Hash. All of the schemes employ a member of the SKINNY family of tweakable block ciphers, which was presented at CRYPTO 2016, as the underlying primitive. In particular, for authenticated encryption, we show how to instantiate members of SKINNY in the Deoxys-I-like ΘCB3 framework to fulfill the submission requirements of the NIST lightweight cryptography standardization process. For hashing, we use SKINNY to build a function with larger internal state and employ it in a sponge construction. To highlight the extensive amount of third-party analysis that SKINNY obtained since its publication, we briefly survey the existing cryptanalysis results for SKINNY-128-256 and SKINNY-128-384 as of February 2020. In the last part of the paper, we provide a variety of ASIC implementations of our schemes and propose new simple SKINNY-AEAD and SKINNY-Hash variants with a reduced number of rounds while maintaining a very comfortable security margin. https://csrc.nist.gov/Projects/Lightweight-Cryptography

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