0
votes
0answers
18 views

One time pad probability

I'm trying to solve a question about one time pads but I'm not sure if my assumptions are correct. I am to assume that I have a one time pad with perfect secrecy. This one time pad is used to ...
0
votes
0answers
5 views

Reducing key shares in Damgård-Dupont threshold RSA

I'm working on understanding and implementing Damgård, I., & Dupont, K. (2005). Efficient Threshold RSA Signatures with General Moduli and No Extra Assumptions. Public Key Cryptography-PKC ...
0
votes
0answers
17 views

Proving the complement property of DES?

I'm trying to show that for a given plaintext (P), key (K), and cipher (C) in the DES algorithm: ...
-1
votes
0answers
20 views

Methods for “chained authentication”

I am currently looking at different methods which can be used to perform what I would call "chained authentication". By chained authentication I mean authentication between two systems that cannot be ...
0
votes
1answer
22 views

Is there a reference that prove that the AES Key Schedule generate random looking round keys?

Starting from uniformly random generated AES master key, is there a reference that prove that an specific roundkey can be considered as uniformly random generated as well ?
0
votes
0answers
19 views

Local UC(LUC) : About the impossibility of any simulations which consists hybrid protocols

In LUC framework, if a protocol has access to an ideal functionality(hybrid model), is it impossible to simulate this protocol? Just because, each of simulators has its own view of the protocol, so, ...
3
votes
1answer
52 views

How hard is it to find plaintexts whose hashes satisfy $h(a)\oplus h(b)=h(c)$?

Given a cryptographic hash function $h$, for example SHA256, how hard is it to find plaintexts $a,b,c$ such that $$h(a)\oplus h(b)=h(c) \text?$$
0
votes
0answers
19 views

Pairing Based Cryptography API [on hold]

What are some of the good Pairing Based Cryptography support in python? I want to design Android based UI and test my pairing security scheme.
0
votes
2answers
62 views

How secure is it to use password as AES key?

I am developing a steganography app where user encrypt any file into an audio file. The user can enter a password to protect the hidden data. The same password is converted as a 256 bit key and the ...
1
vote
1answer
76 views

Merkle hash tree updates

It seems that merkle hash tree (MHT) traversals have been discussed somewhat in the literature, but there does not appear to be much written on inserting, deleting, and updating leaves. Is this lack ...
1
vote
2answers
50 views

Usage of GF(p^m) fields, where p != 2

$GF(2^m)$ Galois fields are widely used in different cryptographic algorithms, for example, in Rijndael. However, $GF(p^m)$ fields are possible with any prime $p$, not only 2, but $GF(2^m)$ fields ...
2
votes
1answer
32 views

Definition of the Decryption oracle

In the context of public-key encryption, what would be a formal definition of the decryption oracle? I know the informal definition (i.e., a function that is available to the adversary and that ...
1
vote
0answers
19 views

Any ideas on login using Digital Signature PKCS

I am curious to know about possibility to login into web application just by identifying the user based on digital signature in usb token. any reference in this direction?
1
vote
2answers
98 views

1 Billion Bit Encryption?

So, browsing through YouTube, I stumbled on this video interview of John Draper (Captain Crunch), one of the first "hackers". He talks for about 3 minutes (until 27:48) about his home rolled ...
0
votes
0answers
35 views

Difference between Ascii85 and Base85? [on hold]

I have a python script that encrypts using Ascii85, but when I encrypt using base85, the output is different. What is the difference? Is it just a different alphabet? ...
0
votes
1answer
37 views

How do I communicate the value of the initialization vector to the end user? Should it be part of the encrypted message?

I am taking a cryptography class and our first homework is to implement a 32-bit block cipher. I implemented a simple block-cipher that uses CBC. Currently, my implementation reads both the 32-bit IV ...
0
votes
1answer
39 views

RSA: How effective is this keypair-trash attack [duplicate]

A question that could very well be part of xkcd's "what if?": Let's say Monica made a piece of software that sends all RSA keypairs to a central database after they're not used anymore. Something ...
-2
votes
0answers
30 views

Is pairing based cryptography computationaly expensive? [on hold]

What is the time complexity of pairing based cryptography compared to other public key encryption schemes? for encoding a single charector what is the space complexity?
0
votes
1answer
43 views

Applications of GF(p) polynomials

A Galois field of the type $GF(p)$, where $p$ is prime, is normally expressed as the ring of integers modulo $p$. If my understanding is correct, it is also possible to represent its elements as a ...
1
vote
1answer
33 views

Generate secure password hashes without access to PBKDF2 or bcrypt

Given is a system, which does provide only implementations of fast hash algorithms (MD5, SHA1, SHA-256, SHA-512). There is no implementation of PBKDF2, bcrypt or scrypt available. The system does ...
1
vote
1answer
40 views

x509 Certificate Signature

I've got a question about the signature of a CA. As I understand, the CA takes the public key of the client and signs it with his own private key by using "md5WithRSAEncryption" (like explained here: ...
2
votes
2answers
79 views

Is this a valid “fix” for deterministic encryption in encrypted databases?

It appears (after doing some light research) that for encrypted databases to be practical enough to be usable, deterministic encryption is required, specifically with regard to the type of encryption ...
0
votes
0answers
33 views

Showing that a function satisfies the properties to be a distance function [on hold]

Let $p$ be a prime and $V_p$ be the associated valulation. Then for all $x,y,z \in\mathbb Z$, $V_p$ satisfies: $v_p(xy) = v_p(x)+v_p(y)$ $v_p(x+y) ≥ min(v_p(x),v_p(y))$ Define a function ...
0
votes
1answer
56 views

Negative exponents in Shoup's threshold RSA?

I'm trying to implement threshold RSA operations, starting with decryption based on Peeters, R., Nikova, S., & Preneel, B. (2008). Practical RSA Threshold Decryption for Things That Think. ...
-1
votes
0answers
23 views

Problem in Entropy ?Please help me solve this [on hold]

Let the message space and cipher space be given by M= C ={00; 01; 10; 11} and the key space K = {k0; k1; k2; k3}. We denote M= {m0;m1;m2;m3} and the probability distribution of message variable M ...
-1
votes
0answers
18 views

Can anyone explain about Correlation and Auto correlation attacks with easy examples? [on hold]

I find examples like 1) Find the correlation and auto correlation of a and b. and b has some data in it.
-1
votes
1answer
31 views

With wrong IV at receiver side, the CFB in better than OFB?

Assume the receiver have a wrong IV (initialization vector), in the CFB mode only the first block of plaintext is wrong but in OFB mode the second and all blocks will be affected. Is that correct? ...
1
vote
1answer
110 views

Why isn't CTR mode (counter mode) used more often?

For the CTR mode, the design is good for parallelization, yes, it seems the benchmark of the program downloaded from crypto++ proves that on an Intel I7 CPU. My question is that as most of CPU on ...
0
votes
0answers
23 views

Problem in understanding Blakley's Secret Sharing Scheme

I need to implement Blakley's Secret Sharing Scheme. I have read below mentioned two research papers but still unable to understand how to implement it. Safeguarding cryptographic keys Two Matrices ...
1
vote
1answer
77 views

How are the AES inverse S-Boxes calculated?

I would like to know, how to calculate the inverse S-box. I followed this link (with affine transformation first, then multiplicative inverse), but the result is wrong. For example, if I use the value ...
1
vote
1answer
36 views

Hardness assumptions on composite order bilinear groups

I am not at all knowledgeable in elliptic curve cryptography. So, here lies a couple of questions that I failed to find answers for to my satisfaction. Is there any known Type-III bilinear pairing ...
0
votes
1answer
50 views

Is there a strong cryptographic reason for GCM's 2^39 - 256 bit limit?

In reading through the original GCM specification (McGrew & Viega '05), the composition of the 128 bit Initialization Vector as a concatenation of a 96b nonce and a 32b unsigned wrapping counter ...
2
votes
1answer
24 views

Is there a strong cryptographic reason for GCM's 2^39 - 256 bit limit? [duplicate]

In reading through the original GCM specification (McGrew & Viega '05), the composition of the 128 bit Initialization Vector as a concatenation of a 96b nonce and a 32b unsigned wrapping counter ...
0
votes
0answers
41 views

Is signing a message just encrypting it with private key? [duplicate]

I have a simple question, When I sign a message (in RSA) does the program encrypt the text with my private key? Because I can decrypt it with my public key. Yes or no. Is signing a message just ...
2
votes
1answer
108 views

Why can't you just clone encrypted data and use it?

Let's take a contactless card for example (one for public transport lets say (i.e. MiCard)), the data is encrypted on the card and encrypted on the reader as far as I know. So how come somebody who ...
-1
votes
0answers
20 views

How to verify pgp digital signature + generic cipher question

When receiving emails, I sometimes see the following: -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I found an integer overflow in PHP, in the conversation of dates to "Julian Day Count" ...
0
votes
1answer
48 views

In ECC, how do I prove that point addition is commutative?

I am studying elliptic curve cryptography and this question is related to the commutative property of point addition operation. Point addition $P_3(x_3,y_3)$ of two points $P_1(x_1, y_1)$ and ...
0
votes
2answers
60 views

Books on cryptography mathematics [on hold]

I am currently reading the Book Understanding Cryptography from Cristof Paar. I am enjoying the book but i don't like to scratch the surface when it comes to cryptography. I would like do dig a little ...
0
votes
0answers
33 views

Crypto library that supports ElGamal PET and Mixnets [on hold]

I am looking for a crypto library that supports VOTING primitives. Specifically: - Zero-knowledge Proofs - Mixnets - ElGamal Plaintext Equality Test (PET) - Commitments UniCrypt is one of the ...
0
votes
1answer
69 views

Proving that an encryption scheme is susceptible to certain attacks

I'm currently trying to prove the following: Where p is a prime number of cryptographic size, prove that: e(m) = am + b (mod p) where a and b are private is open to a known plaintext attack e(m) = ...
2
votes
2answers
67 views

How does BLAKE2 ensure that hash(A) != hash(B) when B = A||0 and both A & B have the same number of blocks?

Suppose I have two arrays : A = a single byte, being zero. B = two bytes, both being zero. B = A||0 (i.e. B starts with A, and differs only by appending a zero byte) BLAKE2(A) != BLAKE2(B) Yet, ...
0
votes
0answers
41 views

Need some help to break a cypher text using unknown cypher [on hold]

I am a programmer and studied quite a bit of math, but I am a cryptography newbie. I browsed through this website, and I am awed. I need help decrypting a letter that was given to me as a ...
-1
votes
1answer
70 views

RSA: how does it work and how is it more secure than symmetric systems

Before starting the question, I know that RSA is naturally a key exchange cryptosystem rather than an antilogarithm fully implemented for encrypting and decrypting data since the length of the secret ...
0
votes
1answer
3k views

Decrypt files with original file CTB-Locker

I have problem called CTB-Locker. It encrypted all of my files on computer and since I have lot of documents that are very important I am in problems! As I read online CTB-Locker uses "elliptical ...
0
votes
1answer
67 views

Will current encryption always remain secure? Is there mathematical proof?

Current encryption algorithms, such as AES, RSA, elliptic curve, etc. work based on known mathematical problems. I am specifically interested in the RSA. Will such security always remain secure? One ...
1
vote
1answer
44 views

Is it a variant of Strong RSA assumption?

Informally, the hardness of RSA/Strong RSA assumption lies in the hardness of factoring a large composite number $N$ having two large primes as its factors. If RSA modulus $N$ is a prime number, then ...
-1
votes
0answers
28 views

Decrypt Encrypted File on the fly and view to user

I have encrypted files on my Web server. Each file is encrypted with a unique symmetric KEY. All symmetric encryption keys are stored on db with public KEY encryption. On user side; Users are logged ...
0
votes
1answer
27 views

Cipher for human interpretation [duplicate]

Please suggest algorithms to encrypt and decrypt text messages that can be easily performed by human in a considerably short time. It doesn't have to be really secure, but sufficient to fool ...
2
votes
1answer
31 views

Is it possible: Derived key based on variable number of private keys?

I have a MySQL database that I want to encrypt with AES_ENCRYPT() and have to provide access to a variable and possibly changing number of users. Is it possible to derive an encryption key based on a ...
3
votes
2answers
71 views

Achieving 32-bit verification code with 16-bit CRC?

I am programming an embedded chip that has a hardware 16-bit CRC module. I have to protect some data bytes $d_0,d_1,...,d_{n-1}$ against corruption caused by sudden loss of power; a 32-bit CRC would ...

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