Questions tagged [side-channel-attack]

attacks using information leaked by implementations of cryptographic algorithms to obtain information about keys or (plaintext) data, instead of (or additional to) using cryptographic weaknesses.

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Sliding windows implementation (Exponentiation by squaring)

I am conducting a research on cpu-cache based info leak caused by using Sliding window in the diffie helman key exchange. For my research I am looking for a real-world implementation of sliding ...
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Can deterministic ECDSA be protected against fault attacks?

In a paper by Barenghi and Pelosi, it was described that fault attacks could be used to derive the secret key when using deterministic ECDSA as described in RFC6979 by @Thomas_Pornin Deterministic (...
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How many AES-operations have to be watched for key-exploit by side-channel attacks?

If I would like to exploit a used key by side-channel attack, one that measures electromagnetic fields, how many runs of the AES-128 do I need to spy on for a successful exploit? I can't use any ...
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Why use argon2i or argon2d if argon2id exists?

So I am currently working on a GitHub project of mine and I want to implement Argon2. The problem is that I dont really know a lot about it. Internet research is not really helpful, because Argon2 is ...
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Timing-Safety in JVM-Languages

How is it possible to write timing-safe code in JVM-languages (Java, Scala, Clojure...)? Is it possible to make libraries like BouncyCastle safe against timing-attacks? I know that even in C it is ...
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4k views

Is ChaCha20 safer than AES with respect to side-channel attacks?

I've already seen some topics on this matter, but I feel like my question hasn't really been answered. Given the following: AES must be implemented in hardware (i.e. using the AES-NI instruction set)...
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1answer
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What is the difference between perfoming Correlation Power Analysis (CPA) in the first AES round and doing it in the last round?

I have a script that helps me to make to make a Correlation Power Analysis (CPA) attack. I am trying to attack the first round. As input, I put: my traces my plaintexts my key The steps to make the ...
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1answer
556 views

Implementation of a side channel attack? [closed]

As homework I need to find the password of a crackme in ascii-coded binary. We were also given a specific part of the crackme (in the image below), which we will need to use a side channel attack ...
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569 views

Protocol for Sharing Blinding Factor with RSA

What is the protocol for choosing blinding factor when RSA is applied with key blinding? (Related question: How would you find the Blinding factor R in RSA blind signature algorithm?) Since blinding ...
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1answer
162 views

Strength of block ciphers under attack [by government level attackers]

So lets say the government has set their top priority to cracking a Veracrypt or Lukes or whatever volume containing highly confidential information. It uses AES or AES(Twofish). How would they start ...
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347 views

How would a side channel attack be carried out in a real life situation?

How would a timing attack against AES be carried out in a real situation? You could not guess the key from the processor's power usage after the plaintext is encrypted, right? And what would you need ...
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889 views

How to analyse traces of a hardware AES implementation?

I am trying to implement the correlation power analysis attack. I have a hardware AES for which I found a trigger which defines the start of the AES calculations. After that I performed an EM curves ...
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Does AES-NI offer better side-channel protection compared to AES in software?

Does AES-NI offer better side-channel protection compared to AES in software? Also, it would be great of you could provide according references in your answer.
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AES-128: How to find cipherkey comparing wrong and right ciphertexts?

I have a .mat file which contains 10 plaintexts and 10 ciphertexts which are correctly encrypted with AES-128 algorithm. It also contains 10 more ciphertexts which are wrongly encrypted. The fault is ...
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1answer
152 views

Is having AES tables on a distinct physical page enough to avoid cache timing attacks?

Reading about typical cache timing attacks, they seem to be based on intentional eviction of cache lines and timing how long an operation takes. It seems as if those attacks rely upon these tables ...
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Why are side channel attacks such as SPA/DPA/ CPA based on the AES SubBytes routine?

I have three questions about AES related to side channel attacks: Why are side channel attacks such as CPA related to the non-linearity of the SubBytes routine within AES? What is the difference ...
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Side Channel Attacks

How to make cipher resist against Side channel Attacks. Specially Timing Attack, Cachet Timing Attach, Simple/ Differential Power Analysis. Uptil now it seems all Standard Algorithms like AES, ...
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269 views

Side-channel attacks for ARM conditional instructions

I'm implementing some cryptographic functions on an ARM Cortex-M4 and would like to be safe against side-channel attacks, like power and timing attacks. For efficiency I'd like to use conditional ...
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676 views

Why should we consider the output of the AES s-box as a “sensitive value” in relation to side channel attacks?

In general, we consider the output of s-box in AES as a “sensitive value” in order to perform a side channel attack. I would be very grateful if you could explain to me the reason of that ...
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1answer
72 views

Higher-Order Side Channel Security and Mask Refreshing: linear function?

I currently read about this paper: https://eprint.iacr.org/2015/359.pdf and I wanted to implement Algorithm 4 / Algorithm 5 on my own. There is one thing I cannot understand: where does function g ...
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1answer
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Why not use `<`, `>` or `==` in constant time comparison?

I am comparing secret data stored in arrays a and b to see which holds a greater value. My current (pseudo)code looks like this:...
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1answer
703 views

Compression-Ratio Side Channel

I'm working through the matasano crypto challenges, and I'm onto set 7, where they describe an attack on encryption/compression oracles. I am having trouble understanding the attacks, more so the ...
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AES sbox security issue - power analysis attack?

I was wondering about whether the usage of a precomputed sbox (kind of a lookup table) could be a serious security issue when using AES. I am new to power analysis attacks, so it is hard to ...
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Are there some well-known crypto APIs that leak information?

Are there any well-known crypto APIs or libraries that leak or used to leak information (it can be the key or anything else)?
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Is it possible to test implementation for side-channel attacks?

When it comes to implementing cryptographic algorithms, there seems to be a big focus on the difficulty of doing so without introducing the potential for side channel attacks and the knowledge ...
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FHE Block ciphers' usage

There are currently FHE implementation for AES Simon Speck, and may be more. Except for speed testing, amortized or not, one meaningful usage is mitigating form side channel analysis. Intel, AMD, or ...
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Conditions for a successful Differential Power Analysis attack

From this paper, there are two conditions for a successful DPA attack: i) there exists an intermediate variable in the implementation that is correlated with the power consumption and ii) this ...
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736 views

How can bit slicing be constant time, when Mix Columns is in the cipher

I'm reading about bit-slicing techniques, and one thing about it caught my mind. The strength with bit sliced implementations are (apart from that they are fast) that they are running in constant ...
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Software timing attack using Kocher method

What's the minimum number of random sample points needed in Kocher's timing attack, so that we can determine enough valid measurements of $A_{i,r}$ and $D_{i,r}$? I'm working from this paper: Volker ...
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How does the split mask countermeasure work on AES?

I am trying to understand the split mask countermeasure which is a masking method to avoid side channel attacks. Let's first describe the principle and then try to apply it to AES. I found this paper ...
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426 views

Exposed raw RSA private key operation

Assume that there is a smartcard or other hardware token that exposes the raw RSA private key operation (modular exponentiation, with or without CRT parameters). Is there any possibility that raw RSA ...
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1answer
62 views

Is it okay to use a variable-time RSA implementation to verify TLS certificates?

RSA as implemented by OpenSSL et al. needs to protect against side channel attacks, at a big performance penalty. However, TLS certificate validation involves no secrets. Therefore, I should be able ...
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108 views

Is rubberhose cryptanalysis a sidechannel - formally?

I recently was engaged in a discussion in Sec.SE where somebody used the term "sidechannel" to actually mean "circumvent the encryption". By what he said it was clear, that he wanted to not bother ...
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How to test an encryption against different attacks [closed]

For the last while I have been reading up on cryptography and the different kinds of methods for encryption (public key, blocks, etc) and the attacks against them. This got me wondering how to ...
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446 views

ChaCha20 immune to timing attacks

What are the reasons because of which ChaCha20 is immune to timing attacks ? Also why is not AES immune to timing attacks?
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693 views

Side channel security of HMAC in software

Assume we have a processor with a symmetric co-processor that supports AES. This processor does however not provide co-processor support for hash algorithms such as SHA-1 or SHA-256. I've got the ...
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2answers
244 views

Are there any disadvantages of using libsodiums helpers for en-/decoding/comparision instead of the native ones?

Libsodium has some helpers, which allow hexdecimal decoding, encoding and also constant-time string comparison. So if you use the php binding libsodium-php you ...
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1answer
119 views

Optimal same-base exponentiation?

I've (finally) implemented the answer to this question in our library, which stated how to transform montgomery curves (and points) to weierstrass curves (and points). Now, for scalar multiplication, ...
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1answer
1k views

How does constant-time comparison work?

libsodium has a method for comparing two byte sequences in constant time. Is the idea here to simply avoid early-out if a difference in the data is detected? When I first heard of such a thing I ...
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1answer
415 views

Which precautions to protect against side-channel attacks on ARX ciphers?

In recent crypto there has been a trend to design ciphers using only the ARX set of instructions - i.e. additions (modulo $2^{32}$ or $2^{64}$), rotations (by a fixed constant) and XORs, examples ...
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Why do crypto libs use table lookups when they're vulnerable to timing attacks?

AESEngine.java, from BouncyCastle, uses table lookups as does aes_x86core.c, in OpenSSL. But per Cache-timing attacks on AES table lookups like what OpenSSL and BouncyCastle are doing are vulnerable ...
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Can string lookups be vulnerable to timing attacks like array lookups are?

Per “Can non-assembly crypto libraries truly be secure against timing attacks?”, array lookups are vulnerable to timing attacks. Like, if you do cresult[map[i]] and ...
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How can a lattice attack be applied to ECDSA signatures?

The aim is to check if it is possible to break the ECDSA cryptosystem under the following criteria. Suppose that each ECDSA signature is generated by using the GLV method for point multiplication (...
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Side channel attack on FPGA AES engine

I actually don't know if this is the right place where ask, but I try. The side channel attacks aren't a negligible problem. There are several ways to protect from these attacks its own IP inside the ...
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Is there a cryptographic algorithm which is immune to side channel attacks?

Is there any cryptographic algorithm immune to side channel attacks based on scan chain? In VLSI point of view.
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1answer
628 views

DPA Attack on HMAC SHA-256

I have read the paper Differential Power Analysis of HMAC SHA-2 in the Hamming Weight Model and I want to understand the DPA Attack. In section 3.2.1 Path 1 (page 4) there is written: The last ...
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1answer
468 views

Double-and-add/Montgomery VS blinding

I'm having a hard time understanding why people use constant-time techniques to counter time-attacks, when blinding seems as good and cheaper to implement. Why do people avoid blinding in ECC?
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side channel attacks against TDES (compared to AES)

We all know AES has some pretty strong side channel attacks, some where (with a couple of hundred know plain- and ciphertext combinations) a key can be derived in a matter of minutes. Others may take ...
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Information-theoretic bound on leakage by timing measurement

I'm looking for an information-theoretic bound on leakage by timing measurement. I'm assuming that an attacker wants to leak out of a black box a secret key of $k$ bits that is secretly injected into ...
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1answer
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Defence against timing attacks

I know this is a difficult subject but would a good defense against timing attacks be not sending a message if the decryption or authentication fails? So if the attacker provides a wrong HMAC for ...