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27 views

Regarding security of blind signature schemes

I'm new to blind signatures, trying to understand security notions of it: blindness and one-more unforgeability. I found out that in the security game for blindness property, the adversary $\mathcal{...
0
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0answers
19 views

Converting Smart Contracts into Arithmetic Circuits

Are there any existing programs available to convert smart contracts into Arithmetic Circuits with which I can implement and experiment with Secure Multiparty Computation (MPC) protocols?
0
votes
0answers
27 views

AES S_BOX Generator additive constants

I try to generate other S_BOX for AES but I don't realize how to choose additive constants for S_BOX from decryption if for encryption it is 0x63 why is ...
0
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0answers
27 views

What Kind of Encryption Algorithm Will Generate Text Like This? [closed]

After the text is encrypted, it looks like this:FYWB UCBH VOHO BCBM ACIG AOFY SHDZ OQS
1
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0answers
19 views

Two ElGamal ciphertexts equivalence

Is there a way to prove that two ElGamal ciphertexts encrypt the same message with different public keys without knowing the private keys? The prover is the producer of both ciphertexts.
0
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0answers
14 views

Whether there is a public key encryption system based on elliptic curve with the property of multiplication and addition homomorphism。

I want to implement it on the intelligent contract and then do the development,because use paillier i cant genereate 1024bits key,so i try to find if there is exit a public key encryption system based ...
2
votes
1answer
203 views

A possible error in the book

So I have been reading this book called "Implementing SSL/TLS using Cryptography and PKI" While going through it, this snippet of code got me baffled ...
0
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1answer
53 views

How to reduce Computational Diffie–Hellman problem and Decisional Diffie–Hellman problem to Discrete logarithm problem

I'm supposed make some reductions but don't even know where to start. Any help would or explanation on how to do this would be much appreciated.
0
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1answer
34 views

How to perform the initial permutations 64-Bit DES to derive $K$?

Perform DES encryption on the first 64-bit plaintext only, what are these 0's and 1's? Do they mean that I need to use this ...
0
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0answers
27 views

Trivariate Coppersmith Implementation

Bivariate Coppersmith is standard package in math software with number theory support. Bauer and Antoine Joux introduced trivariate Coppersmith in https://www.iacr.org/archive/eurocrypt2007/45150361/...
0
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0answers
19 views

Can you derive the AES key if both cleartext and ciphertext are known? [duplicate]

If you have a single 128-bit block data in cleartext and the exact same data encrypted with an unknown AES key (the key length is known, though), is there any possibility of determining that key other ...
1
vote
1answer
45 views

Can I retrieve a re-hashed (hash) value, for instance by additional hashing?

I have a double-SHA-256 of some text $$ h_2 = \operatorname{SHA256}(\operatorname{SHA256}(m)).$$ I don't need the plain text ($m$), but somehow I need to get first $$h_1 = \operatorname{SHA256}(m).$$ ...
0
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0answers
32 views

What does d2i_RSAPublicKey function do? [closed]

I read man (3) d2i_rsapublickey but I didn't understand, what does the function d2i_RSAPublicKey do?
2
votes
1answer
47 views

Encryption with 2 symmetric keys and decryption with one key

Here is my use case: I need to keep encrypted data in Hadoop. The data is encrypted with symmetric key that is being changed every half a year. When data is retrieved it should be decrypted. Lets ...
0
votes
0answers
31 views

How to encode SHA-256 as a quadratic span program?

I'm trying to understand the step-by-step zkSNARK's generation process for proving the knowledge of the hash pre-image (as in this example). However, I don't understand how exactly SHA-256 is turned ...
0
votes
0answers
23 views

Is it correct using Sigma Protocol to do the knowledge proof?

For this background, the prover knows a secret $x$ for $h=gx$. Prove to the verifier that he knows $x$. (I know $h=gx$ is not a NP problem, I just want to practice the Sigma Protocol) Step 1 : $P \...
0
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2answers
36 views

set of integers modulo an integer q in lattice

Some literature about lattices set $\mathbb{Z}_{q}$ in $[-\frac{q}{2}, \frac{q}{2})\cap \mathbb{Z}$ but not $[0,q-1]$ such as "lattice signatures without trapdoors" and "lattice based blind ...
2
votes
1answer
93 views

A hash functin based on XOR and matrix multiplication

Imagine an $n$ bit to $n$ bit hash function defined as follows: Let $K$ and $K'$ be two random predetermined $n\times n$ matrices. Then the hash function $h$ of an $n$ bit number $a$ would be: $$h(a)=...
0
votes
1answer
35 views

Is Commitment Scheme with hash function is a perfectly hiding scheme?

If I use a hash function to construct the commitment scheme, can I say it is perfectly hiding? $m$ is the message $r$ is a random value In commit stage, $$ c = C(m, r)$$ In reveal stage, by ...
9
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3answers
3k views

Using cryptographically random password as both the password and the salt

This question is theoretical, but will help with my understanding. All of my passwords are securely generated using 64 random letters (both uppercase and lowercase) and numbers. Using the argon2i ...
0
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0answers
20 views

Does anyone know of any tools that can decrypt CTR, CFB, and OFB modes in DES? [closed]

I have the key, ciphertext, and IV for all 3 messages. Don't really know what I'm doing with programming it and haven't found any working tools online for them.
-1
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0answers
36 views

Modes of operation that simply uses the tweak of a tweakable block cipher

What is the name of the mode in which we simply change the tweak for each block without the need for complex chaining modes? Is this mode secure? Are there any other recommended modes for native ...
-2
votes
0answers
56 views

RSA formula to find M [closed]

Bob generates public and private keys using RSA encryption algorithm and publishes the public key ($n=614281, e=47$). Alice has a secret message $M$ to send. She encrypts the message $M$ using the ...
0
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0answers
37 views

Understanding a security proof

I am reading the paper "RingCT 3.0 for Blockchain Confidential Transaction: Shorter Size and Stronger Security" (https://eprint.iacr.org/2019/508.pdf), an improvement to Ring Confidential Transactions....
1
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0answers
55 views

Why are integers considered “little endian” in ChaCha20 function?

Why the ChaCha20 - IETF algorithm that generates 512 bit keystream per 32 bit counter (that gets incremented), considers "the input words" that form the internal state as little endian ? What will ...
0
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0answers
17 views

Append-only log with secret metadata?

I need sets of encrypted records which need to be stored in an append-only log. It should be possible to efficiently recover just the headers of each record, so that specific records can be retrieved ...
1
vote
1answer
108 views

Is there any existing obfuscation scheme that makes cipher text indistinguishable from plain text?

Suppose a totalitarian government (in the name of anti-terrorism / protection of intellectual property): has outlawed encryption itself - encryption is only approved for cases where the state has ...
0
votes
0answers
30 views

Importance of Backward and forward secrecy

Which security feature is more important in security protocols being used in different applications? Forward Secrecy or Backward Secrecy
1
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0answers
17 views

Noise NK1 pattern identity hiding

In the official documentation for the Noise Framework there is a section with an overview of the identity hiding for each pattern. The numbering of properties there, obviously, from weaker properties ...
1
vote
1answer
114 views

Chosen plain-text Attack on DES-X with roughly $2^{64}$ DES operations

Here is the quote from P. Rogaway,The security of DESX "the effective key length of DESX with respect to key search is at least 55 + 63 - lg(m) bits" where m is the number of chosen plaintext/...
1
vote
1answer
37 views

Storing values under different keys (e.g. during key rotation)

If you are encrypting some secrets (database passwords, access tokens, etc). When it comes to key rotation, you'll need to store those encrypted values twice, for a short period of time (under the ...
0
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0answers
38 views

Is possible to sign using ECDSA but encrypt using Elgamal

I would like to understand if it is possible to encrypt a message using Elgamal but generate the signature of this message using ECDSA.
4
votes
1answer
71 views

Line by line encrypted logging stored with iv/salt/iterations. How safe is it?

I'm building an encrypted logging application. Log entries are encrypted with AES-256-GCM, using password-derived keys with PBKDF2. The application must support log rotation, and I would like to make ...
2
votes
5answers
133 views

How passwords are fed to key derivation functions?

Suppose I want to encrypt data, send it over the network, and decrypt it on the receiver side. I know the elegant way to do this is by using a symmetric key to encrypt the data and an asymmetric key ...
1
vote
1answer
61 views

modified AES-CMAC algorithm

I want to use AES-CBC for secure firmware upgrades on a microcontroller, with AES-CMAC for checking the integrity of the firmware image. The AES-CMAC algorithm needs a AES-128 encryption funtion. For ...
0
votes
0answers
31 views

How to create two partly similar plaintexts with same MD5 hash value?

The problem I'd like to solve looks like this: There are two plaintexts which differ in length and letters, but contain a few common strings. The first few words and the last few words are the same, ...
4
votes
1answer
316 views

I'm trying to understand which cryptographic algorithm is this

I'm reversing a cryptographic algorithm. This is part of the encryption function translated to python (starting from assembly code): ...
2
votes
1answer
40 views

Merkle Tree space complexity

When searching by using the Merkle tree, the time complexity is $O(\log n)$ but I don't understand how space complexity is $O(n)$. In my opinion, it should be also $O(\log n)$. Can somebody explain it ...
2
votes
0answers
40 views

Faster alternative to shamirs secret sharing algorithm

I recently discovered shamirs secret sharing scheme. Pretty interesting stuff. I noticed that a common case is to split a secret which is used to encrypt/decrypt something else. For example Vault is ...
1
vote
1answer
121 views
+50

The dth root unity in the Pollard Rho Algorithm

In the original paper of Pollard's Monte Carlo Methods for Index Computation (mod p): When the epact is reached, i.e. $$x_i = x_{2i}.$$ then the following equation is formed $$q^m \equiv r^n \pmod p,...
-1
votes
0answers
37 views

Does the following function consider to be a cryptographic hash function [closed]

Would the following be considered a cryptographic hash function $$h(x) = x \bmod 2^{256}$$
1
vote
2answers
62 views

Exclusion proof cost

I am trying to understand what is the cost of non-membership verification for a universal accumulator? More specifically, how can I compute it? Whether using an accumulator is more efficient than ...
0
votes
1answer
56 views

Factoring $n$ in RSA knowing $e$ and $d$

I know that if $(n,e)$ is the public key in RSA and we also know $d$ the private key, then there is a probabilistic algorithm to factor $n$. I'm reading the proof from Fact 1 on here. I understand ...
3
votes
1answer
74 views

Inversion in $GF(2^{10})$ Using Composite Fields

I'm designing a circuit that uses many $GF(2^{10})$ inverters. Normally for this sort of thing I use lookup tables. (Itoh-Tsujii is not efficient for these smaller fields.) This application is for ...
0
votes
0answers
19 views

How to calculate new AES keys for NFC application?

I want to program a couple of AES-enabled NFC tags (for example these) with some custom data, and secure these tags by using the AES features of said tags . In order to increase security, i want to ...
0
votes
1answer
20 views

Common modulus attack with not coprime exponents

lets suppose we have the public keys $(n,e_1)$ and $(n,e_2)$, such that $\gcd(e_1,e_2)=d>1$, and the same message encrypted with these two keys. I'm trying to see if common modulus attack on RSA ...
0
votes
0answers
11 views

CP-ABE secure key management

I want to use CP-ABE (Ciphertext Policy- Attribute-Based Encryption) schemes for multicast communication. How can I share both the public key and secret key among the user? How I do set up an ...
0
votes
0answers
44 views

How to calculate exponent e given textbook RSA public key and modulus N? [closed]

I'm trying to find e and d. I was given: ...
0
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0answers
15 views

How to save an encryption key to a binary file to be used in NIST STS

I wrote a simple logistics function that i use for my pesudo random number generator.I want to test it's randomness so i downloaded a custom windows version of NIST STS. the program rqeuires you to ...
1
vote
1answer
48 views

averaging attack at Google's RAPPOR

I am reading the paper - "RAPPOR: Randomized Aggregatable Privacy-Preserving Ordinal Response". I don't understand how the averaging attack works. I searched for "average attack" but couldn't find a ...

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