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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7
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1answer
78 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 ...
2
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0answers
11 views

Can you extract the encryption key of a computer with full disk encryption via malware? [migrated]

I recently discovered the subject of cold boot attacks which are able to extract the encryption key of the ram memory after the computer has shut down. and from what I understand is that law ...
0
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0answers
27 views

correlation between the timing data produced by different keys with similar inputs in AES

Is there or can there be any correlation between the timing data produced by different keys with similar inputs in AES? If yes, what type of correlation?
13
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3answers
3k 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 ...
0
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1answer
43 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, ...
7
votes
2answers
72 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) ...
4
votes
1answer
49 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 ...
5
votes
2answers
86 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 ...
2
votes
1answer
490 views

The Boneh-DeMillo-Lipton fault attack (RSA CRT)

I am trying to understand the Boneh-DeMillo-Lipton fault attack on RSA CRT signature. Suppose that we sign a message $m$ with RSA-CRT : $d_p = d \bmod (p-1)$ and $d_q = d \bmod (q-1)$ $s_p = h(m)^{...
5
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0answers
59 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 ...
4
votes
1answer
96 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 ...
10
votes
3answers
779 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 ...
4
votes
1answer
35 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 ...
3
votes
1answer
54 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 ...
1
vote
2answers
40 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 ...
1
vote
1answer
44 views

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 ...
4
votes
1answer
86 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?
1
vote
1answer
241 views

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 (...
8
votes
1answer
120 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 ...
4
votes
1answer
64 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, ...
2
votes
1answer
295 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 ...
4
votes
0answers
63 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 ...
10
votes
1answer
1k 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 ...
2
votes
1answer
63 views

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 ...
4
votes
2answers
197 views

Power analysis and exponentiation by squaring

I am trying to understand how one can retrieve the secret exponent via a simple power analysis. Lets suppose that the exponentiation by squaring algorithm is implemented in its simplest form : ...
0
votes
0answers
95 views

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 ...
3
votes
1answer
143 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?
2
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0answers
133 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 ...
6
votes
2answers
195 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 $0 \oplus 1$? ...
4
votes
1answer
1k 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?
5
votes
2answers
200 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.
3
votes
3answers
245 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....
9
votes
2answers
127 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 ...
0
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0answers
103 views

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 ...
0
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2answers
405 views

Practical Attack on RSA

Currently I am designing an RSA based application, and I am thinking of how long should the key be in order to be secure against attacks. I know that RSA 4096 bit key can be recovered using Sound ...
1
vote
1answer
183 views

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 ...
4
votes
1answer
137 views

How did the power measurements translate to AES Key?

A side channel attack is described here. I did not quite get , how the power measurements are used to get the decryption key , can any body explain it?
2
votes
1answer
125 views

Protection of Elliptic Curve Implementations against side-channel attacks [closed]

Recent fast elliptic curve implementations, for example a presentation at Eurocrypt 2014 (earlier presentation slides, the paper) talks about protection against only timing attacks. Why only timing ...
1
vote
0answers
101 views

side channel attacks on AES

Say you have a web application that's performing AES encryption. What sorts of side channel attacks should one keep an eye out for? Timing attacks affect RSA more than symmetric ciphers in-so-far as ...
5
votes
1answer
158 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 ...
0
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0answers
88 views

Where can I find source code of a compiler that secures a circuit (or attemps to)? [closed]

In the paper “Multiparty Computation Secure Against Continual Memory Leakage”, on page 1239 under section “Using an LDS Compiler Instead of OCL Compiler”, the authors discuss why they decided to use ...
3
votes
1answer
1k 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. ...
6
votes
2answers
428 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 ...
3
votes
2answers
292 views

Information leakage in real-time voice encryption

I saw some time ago a post discussing the issues surrounding encryption of speech/voice in VoIP and how it can leak information (can't find it now). Can someone provide an insight into some of the ...
2
votes
1answer
219 views

Which platforms are most vulnerable to Simple Power Analyse Attack

In a "Simple Power Analyse Attack", the difference in power consumption during multiply or square operation is used. In the RSA decryption process with the "Square and Multiply" algorithm, both ...
2
votes
1answer
109 views

/dev/random only needed for key generation / CPU pattern encryption

Consider the following scenarios: using OpenSSL to encrypt a file with Rijndael-256 using LUKS to encrypt a hard-drive that is used every day Exactly when is entropy from ...
4
votes
2answers
674 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 ...
6
votes
2answers
1k 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 $d$ ...
2
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0answers
155 views

How many messages needs to be send to server to get AES key in Cache-timing Attack

I'm trying to evaluate the correlation between key length and the number of messages that needs to be send to server during Cache timing Attack. I read both D. Bernstein, “Cache-timing attacks on AES,...