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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33
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2answers
22k views

Practical disadvantages of GCM mode encryption

It seems that GCM mode encryption has a clear advantage over CBC + HMAC in the sense that it only requires a single key. But it seems that there are some experts here that do not trust it enough to ...
28
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3answers
6k views

How practical are side-channel attacks and how much of a concern are they?

I see a lot of research in very sophisticated side-channel attacks on crypto systems. Most (but definitely not all) seem to follow a trend, namely, the crypto system does something very dumb like ...
26
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5answers
3k views

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 ...
24
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1answer
8k views

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 ...
21
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3answers
4k views

Known methods for constant time (table-free) AES implementation using 'standard' operations?

There are several known methods for implementing AES in constant time using SIMD operations, mostly based around fast byte shuffling (for instance Hamburg and Kasper/Schwabe). Are there any similar ...
19
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1answer
905 views

If a single bit was known through all states in AES, which would cause the most information to leak?

This question is motivated by some bad Verilog. Due to someone being sloppy with port assignments and a output statement, I have an AES core that has a single-bit from a S-Box in the key schedule ...
17
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2answers
1k views

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 (...
17
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2answers
7k views

RSA least significant bit oracle attack

I have been reading up on RSA attacks and came across one that could be called a least-significant-bit (LSB) oracle attack. For the sake of clarity lets define RSA primes $(p, q)$, private key $d$ ...
14
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3answers
2k views

Should I delete cryptographic data from memory?

When dealing with cryptographic data, is there a chance that attacker recovers portion of data I used in my program? Should I try to delete every bit of keys and encrypted data that I used, overwrite ...
13
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1answer
2k views

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 ...
12
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1answer
2k views

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:...
12
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1answer
970 views

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 ...
11
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3answers
2k views

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.
10
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3answers
1k views

Stopping timing attacks on AES: Why is it important to prevent the OS from interrupting the AES computation?

I read the paper Cache-timing attacks on AES (by Daniel J. Bernstein), but I don't seem to understand everything. The author dedicates a long section on how to prevent the OS to interrupt an AES ...
10
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1answer
4k views

AES timing attacks

I'm just interested in cryptography, so please don't expect me to be an expert. ;) I recently read about AES cache timing attacks and found it very interesting. I read the article Cache-timing attacks ...
10
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2answers
150 views

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 ...
9
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1answer
280 views

Are more complex algorithms easier to break with timing attacks?

Is there a point where increasing the complexity of an encryption algorithm will make it easier to break using a timing attack? Or is there no connection here at all?
9
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1answer
3k views

What is “Blinding” used for in cryptography?

What does "blinding" mean in cryptography, and where do we usually use it? Can you describe a sample implementation?
9
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1answer
518 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 ...
8
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2answers
2k views

How to avoid side channel attacks when handling large numbers?

For cryptography, the platforms have limited size as 32 or 64-bit operations. We definitely need big numbers to implement the encryption/decryption and digital signatures for cryptosystems like RSA, ...
8
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3answers
361 views

Are there any symptoms of a side channel attack on the target chip?

I would like to know if there are some symptoms that let me detect if my integrated circuit is actually subject to a side channel attack. For example, are the following potential indicators? ...
8
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1answer
3k 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)...
8
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1answer
189 views

Can the lengths of HTTPS requests be used to deduce which public pages on a site are visited?

I thought of this recently: There are some websites which have many publicly accessible pages, some of which could be embarrassing despite being public (e.g. Wikipedia). The HTML for these pages also ...
8
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2answers
1k views

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 ...
8
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1answer
404 views

Do people not care about side channel resistance?

Recently, I have been browsing a lot through libraries that implementing Shamir secret sharing. I see a lot of code that implements this cryptographic algorithm without any side channel (timing/branch/...
8
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2answers
431 views

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) ...
8
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1answer
330 views

Deterministic RSA blinding

I have an implementation of the RSA private key operation in a context where I don't have access to an entropy source. I'd like to add blinding to it (both message and exponent), to make it resist ...
8
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0answers
113 views

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 ...
7
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3answers
500 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 ...
7
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1answer
370 views

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 ...
6
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3answers
722 views

Why don't table lookups run in constant time?

The Wikipedia article on big O notation says that performing a lookup is a constant time operation. So why are lookup tables susceptible to timing attacks?
6
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3answers
963 views

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.
6
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1answer
435 views

Does blinding work against side channel on RSA?

In the so called "blinding" technique for RSA, prior to decryption, the ciphertext is multiplied by random $r$ raised to the power of $e$; e.g., $C$ is replaced with $C\cdot r^e$; and then after ...
6
votes
2answers
971 views

Cryptanalysis and weaknesses of SEED cipher

I've discovered that a client has SEED enabled in their SSL ciphers, and would like to know a bit more about it from a security perspective. The Wikipedia article doesn't mention any flaws, yet I've ...
6
votes
2answers
541 views

RSA Timing Attack on “Extra” Montgomery Reduction

In "A practical implementation of the timing attack", the authors take advantage of a timing difference that stems from "extra reductions" that occur when multiplying numbers in the Montgomery form. ...
6
votes
1answer
294 views

Understanding Genkin-Pipman-Tromer's ground potential, side channel attack on RSA

I'm pretty sure that by now folks might have come across this research from Genkin-Pipman-Tromer (GPT) on extracting the RSA key used by GnuPG (GPG) just by measuring the ground potential. I'm going ...
6
votes
1answer
95 views

Why do Edwards curves protect against side-channel attacks?

From Wikipedia: One of the attractive feature of the Edwards Addition law is that it is strongly unified i.e. it can also be used to double a point, simplifying protection against side-channel ...
6
votes
1answer
98 views

Is the context of “constant time” algorithms inclusive when you have a clock control?

There is generally a push to make algorithms and components constant time to be resistance to side channel attacks. For instance, AES-NI instructions take as many cycles as rounds; however, I can ...
6
votes
1answer
162 views

Does a masked look-up table prevent cache timing attacks?

When applying the boolean masking countermeasure to a cipher which uses an S-box $S$, a way to handle this nonlinear operation is to recompute a new S-box $S'$ such that $S'(x \oplus r_{in}) = S(x) \...
6
votes
2answers
466 views

power consumption in a XOR

I'm trying to understand how a XOR affect traces of power consumption in a Differential Power Analysis on smartcards. What's the difference in energy radiated in a $1 \oplus 1$ and in a $0 \oplus 1$? ...
5
votes
3answers
459 views

Attack against modular inversion operation using side-channels?

I'm building a device that performs a modular inversions using a secret modulus. I would like to know if it is possible to recover all or part of this modulus by side-channels (timing, power, EMR, etc....
5
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2answers
2k views

Timing attack on modular exponentiation

It is known that computing $a^x \bmod N$ takes $O(|x| + \mathrm{pop}(x))$ multiplications modulo $N$, where $|x|$ is the number of bits of $x$ and $\mathrm{pop}(x)$ is the number of $1$ bits (Hamming ...
5
votes
1answer
2k views

Montgomery Ladder vs Double-and-Add

I would like to know what (if any) are the advantages of using Montgomery Power ladder over the Double-and-Add-Always algorithm. I think that firstly, Monty would be slightly faster than DoubleAndAdd. ...
5
votes
2answers
423 views

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 ...
5
votes
1answer
97 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, ...
5
votes
1answer
355 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 ...
4
votes
2answers
201 views

Why does side-channel security focus on “shielding” rather than “jamming”?

I have always found it weird when in a crypto discussion people stressed the importance of making algorithms runtime-deterministic, to the point of avoiding any compiler optimisations. To me, it ...
4
votes
1answer
349 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?
4
votes
4answers
236 views

Mitigating Side Channel Attack (SCA)

The SCA power attack described in 2016 article called "Power Side Channels in Security ICs: Hardware Countermeasures", depends on the measurement of power consumption fluctuations during AES-128 ...
4
votes
1answer
187 views

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 ...