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-1
votes
1answer
75 views

Theory for pre-paid debit card: card-to-card transfer [closed]

In Sweden in the late 90's they deployed a electronic prepaid cash system system, and if I remember correctly you could transfer money between cards without online access. Wikipedia states that the ...
2
votes
2answers
99 views

One Time Pad for large changing files

i wondered what the security implications are if I do the following. If I had a large file encrypted with a OTP and want to change only a few bytes in the plaintext. what security vulnerabilities do I ...
1
vote
0answers
146 views

Bilinear pairing

I am working on Efficient Construction of Pairings which are being realized by Miller's algorithm. In this algorithm the basic steps are point doubling and line function computation point addition ...
4
votes
2answers
574 views

Update to “Cryptographic Right Answers”

I'm a big fan of Colin Percival's "Cryptographic Right Answers" post. This was written in 2009, which is a long time ago in Internet years. Is the advice still valid or, if not, can someone point me ...
1
vote
0answers
149 views

Blowfish vs. Twofish regarding power consumption

If I wanted to use Blowfish or Twofish to provide security on a device where power consumption is crucial. Regarding power consumption, which one would win? Generally, which algorithms are known to ...
0
votes
0answers
87 views

Looking for crypto with derived keys?

I am looking for cryptographic algorithm or combination of them. Basically I need an algorithm, which can generate private key and for this key can be computed multiple keys based on some seed. So a ...
2
votes
2answers
234 views

How can I perform matching on an “encrypted- fingerprint feature matrix” using Fully Homomorphic Encryption?

I am doing a finger-print authentication process. The feature-extraction using minutiae has been done and I get an N x 6 matrix, where the 6 columns are {$x_i$ ...
4
votes
2answers
254 views

Which concrete applications benefit from Oblivious RAM constructions?

The main motivation for Oblivious RAM (ORAM) is that, for instance, in the "cloud" setting a client outsources his data to a server in the form of encrypted blocks. Later on, he wants to perform read ...
2
votes
2answers
646 views

P10 to P8 in S-DES

I am new to cryptography. During my learning I am facing a problem with S-DES. I am confused where P10 to P8 come from, and I’m ...
2
votes
1answer
150 views

Is it possible to combine two operations rotation and xor?

I can see many xor and rotation operations in cryptography. I just want to make some algorithms fast. So, I'm looking for a way to combine between xor rotation operations. I don't know if it is ...
3
votes
0answers
59 views

space complexity of quantum collision search

Is there a known way to reduce the space complexity of quantum collision search beyond what is offered by the built-in time-space tradeoff, while keeping the time complexity significantly below what ...
1
vote
0answers
109 views

RSA Key Blinding

I was looking the answer to the following question (Timing attack on modular exponentiation), discussing the Private Key Blinding as a countermeasure for timing attacks. Therefore I'm asking if ...
4
votes
1answer
140 views

Generating unsigned, bounded random value using signed bounded random values

Use case: I have a random number generator that can generate random numbers in a range that is limited by a number $x$, say $x$ ranges from $2$ to $2^{(n - 1)} - 1$ exclusive. In this case $n$ is ...
1
vote
1answer
59 views

Computational Diffie-Hellman problem over the group of quadratic residues

Suppose that $N=pq$ where $p$ and $q$ are safe primes. $\mathbb{QR}_N$ is the group of quadratic residues which is a cyclic group with order $\frac{\phi(N)}{4}$. Let $g$ be the generator of ...
2
votes
1answer
124 views

Computing youngest person among 3 while keeping ages private

I already found a protocol to find out who is richer (older) between two parties, but Is there any protocol to find the youngest person among 3 parties, without revealing actual ages?
4
votes
1answer
396 views

Is knowing the private key of RSA equivalent to the factorization of $N$?

Given the RSA modulus $N$ the fastest method to factor it is of sub-exponent order. But, now if I know the private key $d$ of RSA, does that mean I can factor $N$ efficiently?. It intuitively seems ...
1
vote
1answer
181 views

Can 64-bit “PRINCEcore” practically be brute forced?

There is a cipher called PRINCE proposed in ASIACRYPT two years ago. See the paper: “PRINCE – A Low-latency Block Cipher for Pervasive Computing Applications” The cipher divides the 128-bit key into ...
0
votes
1answer
212 views

How to implement a Cryptographic Pseudo Random Function

I need three pseudo random functions which all take a seed S (t-bits long). The functions should map from $d$ bits to $d$ bits $d$ bits to $1$ bit $d$ bits to $t$ bits $d$ is $10$ bits $t$ is ...
3
votes
4answers
2k views

Pseudocode for constant time modular exponentiation

I'm looking to implement modular exponentiation (for RSA) in constant time, but most of the examples I've found are more mathematical descriptions of the operations. Are there any references with ...
3
votes
0answers
133 views

Paper about this secure P2P idea?

Two or three years ago, I was reading something interesting, but then I lost the paper. The paper described building secure and fast P2P networks (not like tor or I2P). Unfortunately, I only remember ...
3
votes
1answer
124 views

Is it possible to track down copies of WW2-era codebooks?

I've got an academic curiosity regarding some of the old Japanese naval codes used during World War II specifically. I'm wondering if any of the codebooks from this era have been made available, or ...
0
votes
1answer
652 views

Decrypting a small Message using RSA with a Private Key [closed]

If I have a private key of (43, 341). What would be the steps I need to take to decrypt a small message using RSA? I have looked ...
-1
votes
2answers
84 views

How do they implement MAC in TLS?

I recently read questions about "MAC then Encrypt/Encrypt then MAC" which made me curious about how they actually use the algorithm. MAC only calculated once either case (according to what I read). ...
1
vote
2answers
353 views

Wrong Test Vector for HKDF with HMAC-SHA256 [closed]

I have implemented HKDF by myself and it seems to work good. I managed to replicate all the test vectors listed here but... except this one: ...
4
votes
1answer
87 views

What is the Geometric Generalised T' Method?

This page by Nicolas T. Courtois mentions Geometric Generalised T' Method. It is described as an advanced geometric algorithm, never published, for finding extra linearly independent equations at ...
4
votes
2answers
184 views

Use cases for “online” authenticated encryption?

What is the the point of an "online" mode for an authenticated cipher? I understand what "online" means in this context. However, I have trouble coming up with applications that would benefit from ...
5
votes
1answer
268 views

Side-channel attacks against ECDH for Weierstrass normal form curves

I hear a lot about why Montgomery curves are used in ECC, and one reason is that the same algorithm can be used to do both point addition and doubling (this is not true for the Weierstrass normal ...
2
votes
1answer
121 views

Encryption mode with chained algorithms

Suppose that I want to encrypt some data using two different algorithm chained (e.g. AES and Serpent) and harnessing the benefits of CBC. I can do: ...
9
votes
3answers
1k views

Elliptic Curves of different forms

Looking at http://safecurves.cr.yp.to/ to find a safe curve, I find that most curves described here are of a different form from that generally used. In Bouncy Castle, for example, ...
5
votes
2answers
102 views

Where did Martin Hellman acknowledge Ralph Merkle's contribution to public-key cryptography?

I am trying to find the article to reference when discussing the Diffie-Hellman key exchange. According to Wikipedia Hellman said that The system...has since become known as Diffie–Hellman key ...
3
votes
3answers
201 views

Is it meaningful to consider the leakage of master key of KGC?

In the Identity-based cryptography, the user's private key in the systems is delivered by the key generation center(KGC). My question is : Is it meaningful to consider the leakage of master key of ...
2
votes
2answers
2k views

Digital Signature using symmetric key cryptography

Generally digital signature is a public key cryptography concept.But it needs high overhead. So is there any publication or link available where 'digital signature using symmetric key' has been ...
1
vote
2answers
155 views

Standard or guidance for entropy collection

I need to write some high-level security requirements which include a random number generator suitable for use in cryptography. I don't need something very formal, this isn't a security certification ...
10
votes
0answers
675 views

Who first published the interest of more than two prime factors in RSA?

Multi-prime RSA is now a well known technique (described here): it uses $k>2$ distinct secret prime factors in the public RSA modulus, with the advantage that, using the CRT, we can gain a speed ...
5
votes
2answers
177 views

ML/NN Cryptanalysis

Is it computationally plausible to use NN/ML to do any of the following tasks? "Real" cryptanalysis. Cyclic neural networks for extended computation, but break the hash all the way through. ...
2
votes
1answer
2k views

Certificate signature with SHA-1 and RSA: where do 1888 bits come from?

Plenty of X.509 Certificates use "PKCS#1 SHA1 with RSA encryption" as the Certificate Signature Algorithm for generating a 2048-bit signature. The SHA-1 hash function generates a hash value of 160 ...
1
vote
1answer
118 views

What is the padding scheme for the original Tiger hash?

The specification doesn't seem to indicate how to pad messages to the requisite 512-bit boundary. What is the padding scheme for the original Tiger hash?
2
votes
1answer
272 views

Short length asymmetric encryption?

I want to send out short messages to the world which listeners could verify to be send from me. The way this is usually done is to encrypt the message with a private key where the readers decrypt it ...
6
votes
1answer
734 views

Keccak padding implementation, and bit ordering

I am trying to implement Keccak in Java for my school work. And I am getting stuck in two places: On the summary page the padding is shown as P = M || 0x01 || 0x00 || … || 0x00 P = P xor ...
-2
votes
1answer
79 views

function of crypt called “ICE” [closed]

Using exeinfo, I have identified a function of crypt called ICE. What is it? How can I find ...
6
votes
1answer
380 views

How can uniformity of hash functions (e.g. SHA-256) be proved?

In reading about the Bitcoin protocol I noticed how much its proofs-of-work apparently depend on uniformity of the SHA-256 hash function. And so presumably do many other applications. How do ...
0
votes
1answer
84 views

Authentication mechanism for low memory, low computing power device

I am looking for an authentication mechanism that works best with low memory, low computing power devices. I came across a paper "A Practical Zero-Knowledge Protocol Fitted to Security Microprocessor ...
4
votes
1answer
191 views

Cryptanalysis of AES on SSD with TRIM enabled

Attack scenario: SSD physically retrieved from a computer that is turned off. The entire disk is encrypted with AES 256-bit (GNU/Linux, LUKS). The SSD has had TRIM enabled for several years and the ...
2
votes
2answers
3k views

OpenSSL PBKDF2 documentation

I'm using OpenSSL 0.9.8 on OSX Maverick, and I want to use a PBKDF but I can't find any doc/man about it on OpenSSL's website. I'm working on QCA, an OpenSSL wrapper for Qt, and when I arrived there ...
2
votes
2answers
174 views

Can anyone tell me the name of this cipher please?

Can anyone tell me the name of this cipher please? I know it's a simple substitution cipher, I just don't know the name of it. Cipher Key: help Cipher alphabet: ...
7
votes
2answers
670 views

Implement deniable encryption with AES/RSA

I'm on a crypto app using OpenSSL (I'm more an implementer/cryptographer than a cryptologist), mainly as a hobby, for now. My app will be able to encrypt a file (not a container) with symmetric or ...
1
vote
0answers
227 views

Pohlig-Hellman exponentiation block cipher

Let $G$ be a group of order $n$ and let $e,d$ be integers such that $ed\equiv 1 \pmod{n}$. Then the exponentiation maps $x \mapsto x^e$ and $y \mapsto y^d$ are inverse maps on $G$. These maps give us ...
1
vote
0answers
223 views

Where can I find examples of ECC implemented in VHDL?

I am looking into implementing ECDSA signature and ECDH key agreement in a Xilinx FPGA. All the examples I have found of VHDL implementations skip over how to construct the low level ECC primitives ...
1
vote
0answers
122 views

Can you provide an example in relation to Hidden Field Equations Multivariate?

I'm reading about Hidden Field Equations Multivariate scheme. My lecture states that the central map is a univariate polynomial $$P(X)=\sum_{i=0}^{r-1}\sum_{j=0}^{r-1}p_{ij}x^{q^i+q^j} \in K[X]$$ ...
0
votes
0answers
44 views

Correlated or biased coin protocols?

There are a number of papers in the literature describing secure/fair coin flipping protocols. Unfortunately in my case, I am looking for coins that are epsilon-biased or epsilon-correlated. I am ...