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 ...

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90 views

Rate my idea: is that a stronger GPG-like algorithm?

I came up with a simple idea but I don't know if it is really secure or not. I know that you shouldn't create any algorithm on your own. I'm just curious, that's all. Algorithm explanation: First ...
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134 views

ECDSA Public Key generation

Referring to both Wikipedia page and ECDSA-cert paper I can understand that, given $\mathcal{E} = \mathcal{E}(a,\,b,\,\mathbb{F}_{2^m})$ as our elliptic curve on $\mathbb{F}_{2^m}$ group $G \in ...
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50 views

Showing that security of a elgamal invariant is insecure

Original Elgamal signature is defined $S(m, \alpha) = (r, s)$, where $$r = g^k \bmod p$$ $$s = (m – r*α)k^{-1} \bmod (p – 1)$$ more information on Elgamal signature can be found here. Variant ...
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2answers
118 views

Cryptanalysis of an certain algorithm

Is an attacker of an cryptographic algorithm allowed to change order of sub-keys but not changing their number in attack? Would it be called an attack on broken algorithm of cipher?
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214 views

Can you explain partial private key extract algorithm in certificateless Public key cryptography?

Related to the algorithms of certificate-less Signature approach of Al-Riyami and Paterson… Why is there a need for a "partial private key extract algorithm"? Why should it be needed when ...
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249 views

What operations are used in symmetric cryptography and why?

In continuation to Why are bitwise rotations used in cryptography?: what other operations are commonly used in symmetric cryptography? Are there particular operations on numbers that are good for ...
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112 views

Trapdoor implementation

Please refer to this secure index paper. On page#6, a trapdoor is defined as ...
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2answers
143 views

Bent Combining Functions

Bent functions are boolean functions with maximum nonlinearity and are widely studied for their potential applications in cryptography. Lets say you wanted to use a simple two input AND gate as a ...
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27 views

Which algorithm do you recommend for practical use to generate unique passwords for each website?

So, in my imagination there is this simple algorithm with only one master password, let's say a prime number 'p', which I have to remember. Using only the address of the website and p, the algorithm ...
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639 views

Are there any Truth Table to Boolean expression converters? [closed]

I am working on Bent functions that are of interest in cryptography. I developed an algorithm that construct such functions. However, I need some tools to calculate boolean expression from the truth ...
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2answers
682 views

Fastest multiplication algorithm for efficient exponentiation in C++?

First I apologize if this question is better tailored for SO, but since I'm using the method for crypto stuff, I thought I'd ask anybody that might know here. Karatsuba algorithm does a pretty good ...
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1answer
94 views

How to hide bit frequency of the inter-packet delays covert channel?

I encode a hidden message as different delays between packets of another data stream. My implementation now is that for each bit, if the bit is 0, a inter-packet ...
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50 views

A question or few about Mental Poker

I have spent some time studying the "Mental Poker" protocol (sometimes called SRA), initially proposed by Shamir, Rivest, and Adleman -- ...
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56 views

Algorithm accepting every passphrase to fool unlegit user [closed]

I'm looking for specific names and literature on crypto algorithms that accept every passphrase input by the user, in order to 'decrypt' - even with false passphrase - and present the unlegit user ...
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50 views

Special random distribution algorithm

I am implementing ring signatures as a part of an authorization system. Since the number of users could get high enough to make computation on end-user devices infeasible, I am thinking of ...
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0answers
56 views

Why is ed25519 batch verification faster?

I've read at a few sources that batch verification of ed25519 signatures are faster than verifying an equivalent amount individually. Why is this? Also, is there a closed form model of the rate of ...
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0answers
18 views

Cryptography — with a semi-priveleged user in the middle — to prevent request-tampering with another server

I'm working on a chat server for a mobile app I am writing. I would like to use a different application server for non-chat related operations and another application for chat operations. I would ...
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0answers
71 views

Parallel-resistant proof-of-work scheme without hidden knowledge

Follow-up to: Parallel-resistant proof-of-work scheme? Is there a proof-of-work scheme that: can only be solved serially; given the solution, can be verified in minimal time; deterministically ...
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131 views

Hash function that is efficient on GPU and poorly suited to ASIC

I have such requirements to the hash function in my project: operating on 32-bit data, not mathematically breakable (built on existing hashes known to be secure), free of branching, as much as ...
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0answers
102 views

Career advice for our readers [closed]

I am a first year math PhD student with work experience and an MS in math. Do you have any advice regarding internships involved with cryptography and other mathematics other than the NSA? Thanks.
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159 views

Method and explanation for calculating difference in speed between DES and RSA

Our assignment asks us to convert an RSA speed in bytes per second to a DES speed in bytes per second. Our professor's treatment of this ("RSA is 100 times slower than DES") seems insufficient. Could ...
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3answers
670 views

Crypto-Compression Algorithms?

I was wondering, whether there exist such algorithms/enciphering procedures which both compress and encrypt the input data. That means, for starters, the output will be both smaller in size and ...
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2answers
262 views

Can you help me with this Random Number Generator function?

By someone's suggestion, I am posting this question from math.stackexchange.com. I want to find out a suitable function or algorithm, which can provide a random sequence like this… Input: $3$ ...
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1answer
142 views

What is the difference between, and security of $Z_p$ and $F_p$?

While reading some papers, I found that sometimes $Z_p$ was used but sometimes $F_p$ was used ($p$ is prime). Usually, the author will only use their subgroups like this: choose a big prime factor of ...
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204 views

Idea for user/pass hashing to prevent rainbow tables, would it work?

I'm very new to cryptography (and security in general, for that matter), but I had an idea that I'm sure is very flawed, but is worth asking. If a computer user, online account, etc, needs to verify a ...
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2answers
327 views

Properties of Ideal Straight P-Boxes

What properties should an ideal straight P-Box exhibit?
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1answer
115 views

Secure way to compare two secret numbers without disclosing them?

For example, two people want to know who is the older, without disclosing their age. Is there a secure way to do this without a third party involved?
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100 views

Is this EdDSA modification secure?

I am hoping to employ a signed set membership system which is valid iff each signer's contribution to the set is present. The system should allow for two or more mutually exclusive signed sets to be ...
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1answer
168 views

Design criteria for AES

I hope somebody can help me understand the design criterias for AES. Therefore, I would be really thankful if somebody could explain "non-linearity" in this context. A criteria for the s-box in AES ...
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254 views

Can you help me understand ECC Cryptography and it's algorithm?

I want to know the basic understanding of ECC algorithm for cryptography. But I am not aware of the algorithm. Can anyone provide me with a basic explanation of the algorithm?
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74 views

Different patterns of different paterns, wildcard [closed]

I'm not realy experienced with programming and such but I am wondering if the following could be implemented in, lets say, python we have the following ciphertext sequence ...
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34 views

Different Diversify key, every time with AES-CMAC [on hold]

I am using the following code and class to generate a diversify key from AES_CMAC. The doFinal method returns different key every time given the input and masterKey are constants. Any suggestion would ...
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52 views

Are there any bi-bidirectionally indistinguishable Asymmetric Encryption Algorithms

I have been using Asymmetric Encryption for a while, and I have come across an interesting concept, and it would be cool if it could be done. Are there any Asymmetric Encryption Algorithms where the ...
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1answer
104 views

What parts of number theory does the RSA algorithm use?

It is said that the RSA algorithm uses number theory. What parts of number theory does it use? I know it uses modular arithmetic and Euler's totient theorem and function. Is that all?
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48 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 ...
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377 views

Why is there a strong distinction between stream and block ciphers? [duplicate]

If I don't err, in the literature a stream cipher is one in which each plaintext bit is processed individually, commonly via xor-ing with one bit of a random or pseudo-random bit stream, while a block ...