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Do simulator based proofs still rely on the ROM?

I have seen many game based proofs using the ROM, do simulator based proofs require it? Is it possible to do a simulator based proof for every game based proof? For context: What are the differences ...
2
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0answers
10 views

What's the hardest composite for Shor's algorithm?

I do understand Shor's algorithm wants the order of an element to be even so that it can use the factoring identity and find a non-trivial factor. But is there a relationship between safe primes and ...
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0answers
18 views

hash tree merkle tree

If I have 32 blocks and I have a fault in two blocks, how many pieces should I touch to detect the error? I tried 20 blocks but this does not work? Anyone who knows what is the difference between ...
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0answers
18 views

Is it safe to store my login credentials in a Veracrypt volume? [migrated]

I have a list of login credentials (usernames and passwords) that I wanna keep safe. I'm planning to keep it in an encrypted Veracrypt virtual drive with AES, SHA-512, and an 8-character password. Is ...
1
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0answers
31 views

Collision resistant hash function implies one-way function

I'm struggling to give a formal proof that $CRH \implies OWF$ using the definition below. Intuitively, I see why a $CRH$ would be "hard to predict" and might be used as a $PRF$, but I'm unable to ...
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0answers
18 views

How many AES 128-bit keys does a MIFARE PLUS tag have?

I know that the question is a bit silly but I dont know how many keys can a MIFARE PLUS tag store in it. Provided that I have a MIFARE PLUS S tag with 4k memory room and the key length is 128 bit, ...
-1
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3answers
51 views

RSA - What to do when message is greater than N

Exmple: $e=3, n=33$ and $d =7$ and Message is $64$.
4
votes
0answers
48 views

Variant of Pollard rho using small factors of p - 1

Given an integer $N$ to factor which is divisible by some prime $p$, suppose you know (or guess) that $p - 1$ has a few small factors, e.g. $3, 2^2, 5$. Define $B$ as a product of small prime powers ...
0
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1answer
43 views

Why are the session keys in DHKE for different values of 'a' the same?

In a DHKE scheme with the a prime p = 467. an element g = 4. The element 4 has order 233 and generates thus a subgroup with 233 elements. after Computing the common key for A. a=400, b=134 B. a=167, b=...
11
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1answer
1k views

What systems of robust steganography are out there?

By robust, I mean resistant to common image transforms (reversal, crop a non-multiple of 8 pixels off and recompress, blur, solarize to 64 levels, then interpolate, and sharpen, change compression ...
-2
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0answers
34 views

Differences and similarities for factoring, GCD method and brute force

I am trying to understand the difference between factoring RSA keys and using the GCD method to find the prime numbers. Does one take longer than the other? Is this what is meant by brute force?
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0answers
8 views

Zero knowledge proof - Hash [duplicate]

How can I prove that I know the input value of a given hash output without revealing the input? Say for example: sha256("abc123") = "6ca13d52ca70c883e0f0bb101e425a89e8624de51db2d2392593af6a84118090"....
-2
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0answers
37 views

how decipher youtube url path? [on hold]

whats best approach decipher youtube url? am writing a java application that has to download youtube videos that have help me for my studies.i have tried use many from different developers but it ...
-1
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0answers
17 views

Steganography Decode [on hold]

I am wondering about the security of a technique of steganography which involves hiding a text (unencrypted) by changing cases. 0 is lowercase and 1 is uppercase and there is data embedded in binary. ...
1
vote
1answer
61 views

Can the RSA accumulator scheme be converted to Elliptic Curve math?

Is it possible to translate the RSA accumulator scheme directly to EC without requiring bilinear pairings? In RSA we have: $A_{n+1} = A_n^c$ st. $\{c \: \textrm{prime} \: | \: c \in [\...
1
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1answer
47 views

Secure Communication

Focus: I have to design a secure keep alive communication protocol and was wondering if it was necessary to sign the ciphertext after the session key has been generated as an attacker will not know ...
-1
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0answers
15 views

Williams's implementation of Rabin cryptosystem? [duplicate]

Williams' implementation of Rabin's Cryptosystem , where b=1/2[(1+m/n)] is being used to verify original decryption message .but my question why this formation likewise , is it any formula for ...
0
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1answer
27 views

Why does a transcript which is indistinguishable from a fake one show zero knowledge?

Is there an intuitive way to understand why having a transcript that the verifier could have created themselves and is indistinguishable from a real transcript , shows zero knowledge?
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0answers
50 views

Differences between Gcd and factoring [on hold]

please can someone explain to me the difference between the following. Using two different numbers I. E one is the rsa key and the other a number working from 2 upwards to work out the Gcd, until the ...
-2
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0answers
32 views

Which chipre starts and and with $ [on hold]

I have this cipher but can identify which cipher it is $1vdLMPbtx"*_4S6P@8j.#V,]!$ and this one also ...
0
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0answers
25 views

Secret sharing with one smaller share [duplicate]

Given a t-out-of-n shared secret scheme with the message space characterized by binary string of length l, why if one share is smaller than l the scheme is insecure?
-1
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0answers
31 views

I have a homework question to decipher a piece of text [on hold]

All the info that was given is yorhhufoob lyerlfh wlxgli If anyone solves it please tell me what crypto method was used and the deciphered text, many thanks! :)
0
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0answers
26 views

Problem with decode hexadecimal code. Could you help me? [on hold]

Im new here, its my first post here. I don't have strength anymore and I need your help :D. I got wall of the text: ...
1
vote
1answer
48 views

Why there isn't a consistent key transform function of HMAC?

I am currently learning, the internal working of HMAC. There exists a key transformation process in the beginning, which works as follows:- Make the length of $K$ (Key) equal to $B$ (number of bits ...
0
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0answers
27 views

How to check the strength of a symmetric key cryptographic algorithm (New/I designed) [on hold]

Reliability/Strength Test Needed I have designed a symmetric key cryptographic algorithm on my own and developed it.(block cipher)I need to test this algorithm's reliability or how much strong or how ...
0
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0answers
17 views

Simple Mechanisms For Hiding Data in Images [on hold]

My teacher for extra credit said we can do a paper on cryptography of our chosing. I thought I would chose ways of hiding and passing data without anyone knowing. I figure I may as well ask the ...
0
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0answers
39 views

stream ciphering question

If I have the size of the block and the size of the data input, how can I calculate the number of bits to the pad before the data entry process? I tried 2 ^ n (n is a data input byte), but this did ...
1
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1answer
31 views

Authentication and encryption using a simplex communication channel

Is it possible to authenticate a client with encryption on a simplex communication channel without the use of authoritative root certs?
3
votes
0answers
77 views

Why is the NIST recommendation for the private key exponent so much smaller than the modulus?

NIST recommends a 256-bit private key exponent for DLP with a 3072-bit modulus. This question answered how the modulus was chosen/calculated, however, why isn't the private key size closer to the ...
4
votes
1answer
65 views

A hash-based pseudorandom function

Let $H()$ be a cryptographic hash function. Question: Can we consider $c= H(r||i)$ as a pseudorandom value, where $i$ is a public value, $1\leq i\leq n$, and $r$ is a large uniformly random value/...
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0answers
36 views

Alter CBC plaintext by altering IV [duplicate]

I am building on this answer. Essentially I have an initialisation vector $iv$, a ciphetext $c$ and a plaintext $p$. The plaintext was encrypted using AES CBC. The aim is to modify the first 4 ...
0
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0answers
21 views

ECIES 1363a-2004 implementation in openssl [on hold]

I'm using openssl library to implement an ETSI standard and, more specifically, to realize communications with a PKI. To do that I must use the ECIES encryption scheme but it isn't implemented in ...
-1
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0answers
56 views

How to find prime number q in RSA?

To be assumed in RSA key generation algorithm $p$ is a constant prime number and $e$ is an arbitrary prime and also $d$ is an odd number that is relatively prime to $e$. Based on these conditions ...
0
votes
1answer
57 views

What is a good, easy-to-implement hash algorithm for avoiding hash collisions?

I am working on a proxy dll for DirectX 9, and eventually DirectX 11, which dumps textures uploaded via the cpu to files on the disk. Crucial to some of the features I wish to implement is the ability ...
1
vote
1answer
45 views

Interpretation of certain results of NIST Test Suite

I am using NIST Test suite on a PRNG and have a confusion regarding some specific results. Following is the part of the results: ...
0
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0answers
28 views

About LFSR based M209 Cipher Machine

Can some one please express M209 Cipher Machine in terms of LFSR with Diagram or any simple method?
1
vote
0answers
44 views

I need to send 16 bytes using ECC keys on a resource-constrained device

I have a system where a resource-constrained device has to send 16 bytes. It has its ECC key pair, and a peer's Public ECC Key. We're using the p256 curve. The device also has an AES-128 hardware ...
0
votes
1answer
45 views

Can an encrypted message be derived from only keys?

I recently started teaching myself cryptography, and had an idea while reading up about basic ciphers. Instead of passing ciphertext between Person A and Person B, which can be broken if intercepted ...
1
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0answers
18 views

Shamir Secret Sharing: Using $a_0 \ldots a_k$ to store secret? [duplicate]

Let's assume I have a truly random secret $s$ that is 256 bits long, and I want to use SSS with e.g. $(k=4,n=8)$. The normal approach is to set $a_0=s$ and choose $a_1 \ldots a_{k-1}$ randomly, ...
0
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0answers
33 views

Fastest implementation of SHA256 in software without Intel SHA Extension for a normal Intel CPU based PC [on hold]

I'm implementing SHA256 myself using a normal PC, it never supports SHA256 Extension of Intel. What implementation of SHA256 is the fastest in software without Intel SHA Extension, even faster than ...
3
votes
2answers
541 views

Setting MAC field to all-zero to indicate unencrypted data

I'm currently working on a project where we transmit data between two systems. The data is generally encrypted before transmission, however there are certain transmissions that are unencrypted. We ...
1
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0answers
31 views

Differential privacy RAPPOR article proof doubts

Recently I've been trying to understand the RAPPOR proof: \begin{eqnarray*} P(B' = b' | B = b^*) & = & \left(\frac{1}{2}f\right)^{b'_1}\left(1 - \frac{1}{2}f\right)^{1 - b'_1} \times \ldots \\...
-1
votes
1answer
45 views

What are the length of ciphertexts when 16 bytes and 18 bytes of plaintext using ECB?

What are the length of ciphertexts when 16 bytes and 18 bytes of plaintext are encrypted with AES using ECB mode?
1
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0answers
40 views

Efficient protocols for set membership proofs with private sets

I found the paper on Efficient Protocols for Set Membership and Range Proofs in which efficient protocols for the following problem are discussed: Given a commitment $C_v$ to a value $v$ we want show ...
3
votes
1answer
73 views

Enigma message decode errors, and protocols to prevent them

I was looking at some Enigma messages for some random reasons, and I wondered if there were ever issue pulling the correct words out the strings of characters of if there was a protocol for it. For ...
-1
votes
1answer
82 views

Double hash question

I would like a valid Bitcoin address (derived from a private key created by rolling a pair of hexadecimal dice 32 times) to be the private key of any private / public cryptography. So if I encrypt a ...
0
votes
0answers
14 views

Schnorr authentication protocol vs Schnorr signature Scheme

As I understand the schnorr authentication protocol is an interactive protocol where a prover WLOG proves to a Verifier that he possesses the discrete log to some group element. If we use the Fiat-...
0
votes
0answers
47 views

If I have two ECDSA signatures that use the same k (nonce) but different secret keys, can the secret key be computed?

I have two ECDSA signatures $(r, s_1, z_1)$ and $(r, s_2, z_2)$ where $s_1 = (z_1 + r*x_1) / k$, and $s_2 = (z_2 + r*x_2) / k$. Can $x_1$ & $x_2$ be computed?
0
votes
1answer
34 views

Factorization of the public value $N$ from the RSA cryptosystem

It is mentioned here that the public value $N=p*q$ of the RSA cryptosystem can be factorized if one of the factors is reused. Thus, if $N_1=p*q_1$ and $N_2=p*q_2$ and only $N_1$ and $N_2$ are known, ...

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