Questions tagged [algorithm-design]
Design of cryptographic primitives (algorithms), like block ciphers, stream ciphers, random-number generators, hash functions, MACs, key exchanges, public-key encryption or signature schemes. Also tag with the relevant type of primitive. If you ask about a known existing algorithm, also tag with its name.
886
questions
0
votes
2
answers
61
views
New Service to Service Protocol Presented for Public Scrutiny (Time-based Token Signing), Is it Safe?
I came up with the following protocol to provide a life-time for JWT tokens while differentiating services to communicate securely with web services (service-to-service) using symmetric key signing ...
2
votes
0
answers
84
views
Fast algorithm for finding parity of an RNS number
Does anybody have a library of fastest parity finding algorithms in RNS representation? By parity I mean $x \bmod 2$ where $x$ is the number between $0$ and $N=\Pi m_i$ and all moduli are odd.
I have ...
- 21
0
votes
0
answers
24
views
Is there any bijective obfuscation scheme which maintains a byte order (e.g. sorted) or does so after not too many trials? (for 128bit = 16 byte)
We have given 16 bytes and apply some order to them. For example sorting them by their absolute value.
We want to obfuscate them as best as possible while maintaining their order. That means if we ...
- 433
0
votes
1
answer
58
views
wrting algorithm for torsion group elements
Yesterday,I took an exam. There are two questions I received very low points. I will write the first question in this post.
The question says let $E:y^2:x^3+kx+1$ in GF(p) be an elliptic curve where p ...
- 22.5k
1
vote
1
answer
111
views
Construction of Blake2 and Cha Cha
Recently, I was reading about Blake2B and its properties regarding randomness and security, and its connection to Daniel Bernstein's CHA CHA digest. As a budding cryptographer, I find it doable to ...
CommunityBot
- 1
1
vote
0
answers
36
views
Choice of algorithm for ECDLP when you have information regarding private key
Okay, I have a ECDSA public key $P$. The curve is arbitrary and not necessarily secure.
The finite field of curve, $q$, is a $315$ bit prime. I know the following information regarding key:
The ...
- 95
3
votes
2
answers
3k
views
Combine two sha512 hashes to a single hash
Assume I have two data fragments: $Frag_1$ and $Frag_2$.
I can build sha512 hashes the usual way with $SHA512(Frag_1)$ and $SHA512(Frag_2)$ and then hash the two fragments appended to each other:
$$...
2
votes
1
answer
172
views
How to identify if a legacy encryption algorithm used in my programming language is secure?
I used an open-source programming language called Lucee / Cfscript that is closely related to Adobe Coldfusion. The default function that developers use to encrypt and decrypt data (usually for ...
- 141k
5
votes
1
answer
2k
views
One ciphertext, multiple keys, multiple messages
I recently came across the following idea, does anyone know a name and if it is used?
A wants to send B a message (A and B know both have a common secret
key) and C wants to intercept it (without the ...
- 48.5k
0
votes
0
answers
53
views
Does diffusion also include the reducibility inability of the $n$-times appliance of an encryption scheme? Or has this another name? Any proof for it?
With optimal diffusion the change of a single input bit should change every single output bit equally likely with a chance of 50% each (in mean).
But this does not necessarily mean it makes it ...
- 21
3
votes
1
answer
186
views
Testing whether the Euler Totient of a number equals to certain value
I have solved a problem in Project Euler. My solution was based on the finding the all numbers whose Euler Totient value equals to $13!$
However, while I was working on the problem, I thought that: &...
- 111
4
votes
0
answers
1k
views
Fastest known Elliptic Curve Cryptography "solution" (coordinate systems (multiple?), algorithms, precomputed values etc)?
TL;DR: Does anyone have a reference to a study, implementation of different algorithms or otherwise "truth" about which solution - a set of coordinate systems and algorithms that enables the ...
- 22.5k
0
votes
0
answers
32
views
Implementing Secret Sharing Among Multiple Parties
I'm working on a scenario where a safe has a lock code '42', and this code needs to be shared securely among four individuals. The goal is to set up a system where at least two out of these four ...
- 101
1
vote
0
answers
33
views
Grow-only set homomorphic hash function from semigroup?
I have been exploring Bellare and Micciancio's "randomize-then-combine" paradigm for deriving set homomorphic hashing functions. I am particularly interested in grow-only sets, such that ...
- 131
0
votes
0
answers
66
views
Key-dependent cipher generation
Is there any cryptanalysis possible if the cipher itself is deterministically derived from key material?
For example, suppose you have n building blocks (ARX primitives, AES ops, other primitives) and ...
CommunityBot
- 1
-2
votes
3
answers
162
views
Can a very efficient RSA factoring algorithm be worth money?
If someone had a very efficient RSA factoring algorithm, would a company or government entity be willing to purchase it? What factoring time would be considered fast, months, days, hours, minutes? ...
- 1,228
2
votes
1
answer
65
views
Which reordering should I use for an 8-bit S-box?
I'm designing a cipher which has key-dependent S-boxes. The procedure is like this:
Transform the key (a string of bytes) into 96 16-bit words (the high bits are ignored, but make a difference when ...
CommunityBot
- 1
2
votes
1
answer
65
views
Rationale for BLAKE2 message schedule?
BLAKE2 uses a message schedule I did not see before. It uses permutations of pieces of the message block.
The BLAKE2 book did not state the rationale for such a choice and how it contrasts with the ...
- 3,361
0
votes
1
answer
230
views
How do bad actors manipulate game results in real time within 'provably fair' gaming systems?
Ive been assigned research involving online gaming companies and their use of cryptographic algorithms to produce 'provably fair' results. The largest player in the industry uses a method involving a ...
- 3,361
1
vote
1
answer
205
views
Truncating ciphertext as encryption and to decrease bandwidth in code-based PKEs
Since code-based PKEs work by correcting error introduced into the ciphertext, and since truncating ciphertext constitutes both saving in bandwidth and introducing "errors", my question ...
- 36
1
vote
0
answers
81
views
Can the requirement to increase rounds with key size be bypassed?
When taking AES for example, the number of rounds increases as the key size increases.
This is done in order to adequately diffuse key bits into the state of the cipher.
Suppose you replace the AES ...
- 224
2
votes
1
answer
76
views
Oribatida masking question
Why Oribatida uses previous capacity $V_{a+m-1}$ instead of current capacity $V_{a+m}$ for rate masking?
- 2,126
1
vote
1
answer
154
views
Double- and -add algorithm
I am currently doing the elliptic curves and I'm stuck for 8 hours without finding solutions. I under stand the process of double and add but don't know how to obtain 5 * 8P = 4OP =11 P. 11 P was in ...
- 48.5k
3
votes
3
answers
1k
views
Why is SHA-2 considered an ARX construction when it also uses non-ARX operations?
SHA-2 makes use of non-ARX non-linear operators such as the Choice and Majority functions:
\begin{align}
\mathsf{Ch}(E,F,G) &= (E \wedge F) \oplus (\neg E \wedge G)\\
\mathsf{Ma}(A, B, C) &= (...
- 48.5k
0
votes
1
answer
76
views
Is it possible for XTS to use two different key sizes?
As an example could be XTS with a 512-bit key that treats the key as one 128-bit key and one 348-bit key.
As to why I'm asking it's because XTS runs on one large key that it treats like two keys. ...
0
votes
0
answers
54
views
Open-Source Shamir Secret Sharing Hardware Implementations in GF
Is there any hardware implementation of Shamir's secret-sharing method available? I have only go the following two implementations in the existing literature.
Paper 1
Paper 2
Anything more in the ...
- 1
2
votes
3
answers
4k
views
DES Encryption Algorithm all 64 bits for key instead of 56 bits
Would a DES algorithm that uses all 64 bits for the key instead of just the 56 bits be more secure? I have been thinking about it but those 8 bits used for parity are very useful and but including ...
- 48.5k
0
votes
0
answers
107
views
What is the AEGIS design rationale for one way rounds and slow diffusion?
The AEGIS reference document doesn't specify why the authors chose a slow diffusion process and a one way round transformation.
As you can see the previous state is XORed with AES applied to itself ...
- 224
1
vote
0
answers
137
views
Can a Full-State Keyed Sponge be used as AEAD by using XEX?
Full-State Keyed Sponge (aka Donkey Sponge) is when a message is absorbed into the full state of the sponge.
Such an approach to MAC construction is considered secure. 1
However for an AEAD or a ...
- 224
28
votes
6
answers
31k
views
Are there hash algorithms with variable length output?
I understand that for example MD5 produces a 128 bit hash value from a given text of variable size. My question is if there is a hash-like algorithm that will produce a hash value where one can ...
- 46.1k
0
votes
1
answer
91
views
Does ISAAC really guarantee a cycle length of at least 2**40?
I just noticed that the FSE 1996 conference paper which defines ISAAC mentions a counter variable cc.
This variable is said to be the reason why ISAAC has a ...
- 141k
2
votes
0
answers
66
views
Is ISAAC+ actually an improvement over ISAAC?
I just tried to implement ISAAC from scratch, using the Jean-Philippe Aumasson paper from 2007 as a reference.
This paper gives a definition of the original ISAAC algorithm as well as the improved ...
- 141k
6
votes
2
answers
551
views
Length-preserving all-or-nothing transform
Is there any known way to construct a length-preserving all-or-nothing transform? In other words, a secure all-or-nothing transform where the length of the output is the same as the length of the ...
1
vote
1
answer
81
views
DDT for boolean functions must contain only powers of two
I see in many discussion on differential cryptanalysis of SBOX (and others boolean functions, see SIMON-like round functions, SPECK-like round function) the idea of reasoning in terms of weights ...
- 22.5k
36
votes
3
answers
5k
views
What are recommended, general strategies to start block-cipher design and/or analysis?
I (and many others for that matter) have always been fascinated by the inner workings of the modern building block of cryptography: block ciphers.
Now, the resources on the "black art" of ...
- 22.5k
0
votes
0
answers
9
views
Lower bound on additive error when releasing vector of values differentially privately
I have a vector of $n$ elements where each entry is a non-negative integer. Neighboring vectors differ in one element where the absolute value difference between the elements that differ is $1$. I ...
1
vote
0
answers
36
views
How are elliptic curves designed for encryption purpose? [closed]
Why can't we use any random elliptic curve? What are the properties that need to be satisfied?
- 11
1
vote
2
answers
83
views
Given $i$ keyed-$PRP$ labels $\ell_{i,x}$ from a $2^{256} \times 2^{256}$ Sudoku (Latin-square), how difficult is it for an adversary to solve?
There's a keyed-permutation I'm playing with, $\ell_{i,x} = \pi_i(x_i)$, which is a bijection $X \leftrightarrow X$, where $|X| = 2^{256}$, and whose evaluations on plaintext inputs $x_i$ perfectly ...
- 773
0
votes
0
answers
47
views
Is combining Elgamal algorithm and RSA algorithm for key generation and AES+RSA algorithm for encryption and decryption a novel approach?
Key generation: Key Generation
Firstly, the RSA algorithm will be used to generate a public and a private key.
Generate two random prime numbers p, q.
Select RSA public key, P k such that gcd(P k, Φ)=...
0
votes
0
answers
48
views
Does randomization make a big difference in the output of the BKZ algorithm?
We all know that block Korkine-Zolotarev (BKZ) algorithm is essentially a deterministic lattice reduction algorithm. However, in the actual implementation, the BKZ algorithm contains some ...
2
votes
1
answer
418
views
Choosing encryption algorithms and protocols in military systems
Militaries use their own cryptographic algorithms, those of a private third party, or ones that are openly available. However, fear of a backdoor having been planted in publicly-available encryption ...
2
votes
1
answer
231
views
Is Python secrets module using a unsafe RNG on Windows?
The Python secrets module claims to produce cryptographically secure random numbers. I did some research on which random number generator is used when you call the secrets module on Windows. I found ...
1
vote
2
answers
256
views
State recovery algorithm for Xorshift128 given modular outputs
I am researching the Xorshift128 PRNG. I am particularly interested in recovering the state given a set of outputs that have the remainder taken with different values.
A common way to take a unsigned ...
CommunityBot
- 1
0
votes
0
answers
82
views
Why is decryption algorithm usyally deterministic?
For security against Chosen Plaintext Attack (CPA), we need randomized algorithms for encryption. But in some schemes (maybe almost all of them) take decryption algorithm deterministic. This procedure ...
- 438
3
votes
2
answers
278
views
Are there any LFSR-based ciphers with variable feedback polynomials?
All LFSR-based stream ciphers that I know of use a fixed feedback polynomial (i.e. the taps are always in the same position). I know that, at least for non-trivial output lengths, it is necessary to ...
- 22.5k
1
vote
1
answer
115
views
Enigma Questions: Eliminating the can't encode to itself flaw? Maybe not a flaw
I am currently writing a paper in my old age for the fun of it. I feel that the enigma machine had gotten a bad wrap for some of its flaws. I decided to write a machine simulation to see if I can ...
- 23.9k
1
vote
0
answers
40
views
Is there a type of method where multiple keys are involved, and final key produces invalid results unless all prior keys are used?
I'm looking for a mechanism for a type of cert/key signing, where multiple keys need to sign/encrypt something, and a final key/method does not product a valid confirmation unless all those keys did ...
- 457
1
vote
0
answers
72
views
Is there a good website to circulate RFCs [closed]
I'm drafing an RFC for a low computation crypto algorithm, intended for low power bluetooth communication. Likely without a connection using advertisements only.
It's going to include raw C code ...
- 22.5k
1
vote
1
answer
83
views
What non-trivial benefit does including a "context"/"signer info" provide in SM2-DSS and EdDSA?
While implementing SM2 DSS and reading RFC-8032 for EdDSA, I noticed that, both families of schemes provide provisions for including a "context" (in EdDSA) or "signer info" (in SM2 ...
- 141k
0
votes
1
answer
110
views
Extracting genome from a Ciphertext
Cryptography is the practice of securing communication from unauthorized access. One way of securing information is through encryption, where plaintext (clear text) is transformed into ciphertext ...
- 141k