0
votes
1answer
166 views

What is the difference between various modes in FPE?

Format preserving encryption has three modes FE1( FFX) , FE2(VAES) , FE3(BPS) . All of them are based on Feistel Networks .Can somebody explain how they differ from each other ?
0
votes
1answer
69 views

Hash of multiset of values, which lets me compute the hash of the union

Cryptographic hash functions normally take as input a bitstring. I am looking for a hash function that takes as input a finite multiset of values. In other words, given $S \subset \{0,1\}^*$, I want ...
0
votes
1answer
179 views

DSA generate signature and verify

I'm trying to generate a signature for DSA with the following parameters: $p = 23$ , $q = 11$ , $g = 3$ , $H(m) = 8$ , $x = 5$ for the life of me, I cannot choose a random $k$ ($0 > k > q$) ...
0
votes
1answer
156 views

Is AES a linear hash?

So, having read a variety of documentations on AES encryption, I came to the unknowledgeable conclusion that the key schedule applied to the array of chunks, and not just the 14 cycles on a single ...
0
votes
1answer
74 views

Advise key management protocol

Assume that sender and recipient both already have each others public keys(certificates). Sender needs to generate session key to encrypt some data and sends encrypted data to recipient. All offline - ...
0
votes
1answer
58 views

What makes adaptive memory attack difficult for the adversary?

On page 11, definition 2 of "Simultaneous Hardcore Bits and Cryptography Against Memory Attacks", the paper outlines the following steps (PK,SK) public key and secret key are generated by defender ...
0
votes
2answers
110 views

Create a field in PBC

Edited (I removed the emphasize on Integers): My question is partly cryptography and partly programming, I would appreciate any help on any aspect of it :) I want to use PBC library to do the ...
0
votes
1answer
79 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 ...
0
votes
1answer
88 views

Best hash size for hash trees

I want to know if having a 8-byte hash value is better than 16-byte hash value for use within hash trees. My mind tells me that the shorter the hash value, the better. But doesn't a smaller hash ...
0
votes
2answers
231 views

How is SSL secure from rogue Certificate Authorities?

There's one thing that I've never quite understood about SSL (which perhaps means I don't understand SSL at all): how is SSL secure from rogue Certificate Authorities? This is probably best ...
0
votes
1answer
79 views

Encrypting a broadcast channel

We're building a data service that is expected to go out through a single "fat pipe" channel. The design requirement says that the data in the channel must be protected by authentication and ...
0
votes
1answer
88 views

Sematically Secure McEliece

I am read the Lemma 2 (pp13) in the paper "Kazukuni Kobara and Hideki Imai: Semantically Secure McEliece Public-Key Cryptosystems –Conversions for McEliece PKC– (PKC 2001)". Related to the question ...
0
votes
1answer
175 views

RSA - Ecrypting the same data with the same public key = same ciphertext?

If an adversary knows my public key and guesses what was my plaintext, can he test for it somehow? The most obvious way is encrypting the guessed plaintext with my public key and the same parameters ...
0
votes
1answer
72 views

PBKDF2 when dkLen and hLen have the same size

I was reading RFC 2898 and something is not clear to me. When I use PBKDF2 with SHA-256 and I want a derived key with length 32 bytes (the same length as my hash function output), your derived key ...
0
votes
1answer
69 views

Is it possible to create a Bilinear Function with Already Assigned “Multiplicative” Input Groups?

Assume that we have an already assigned Multiplicative Cyclic Group $\mathbb Z_p^*$ with order $q=p-1$, and $p$ is a prime number, is it possible to create a bilinear function $\hat{e}: \mathbb Z_p^* ...
0
votes
2answers
713 views

Deriving HMAC key and cipher key from passphrase? [duplicate]

I'm encrypting a file with AES-256 in CBC mode. I needed to add an HMAC for authentication and validation of the file contents and passphrase, so I used a SHA-256 HMAC over chunks of my file ...
0
votes
2answers
273 views

Computational indistinguishability and example of non polynomial algorithm

The wikipedia page on computational indistinguishability says that two ensembles are not distinguishable if "any non-uniform probabilistic polynomial time algorithm A" cannot tell them apart. To help ...
0
votes
1answer
94 views

RSA Certificate Owner and Issuer line meanings?

Apologies if this question is not in the right place. I've recently been looking through some RSA certificates ( specifically, Android apk .rsa files) and I'm having trouble deciphering the one and ...
0
votes
2answers
367 views

What are some approaches to attack an triple key polyalphabetic cipher when the IV key and PT key are known?

The cipher is an triple key polyalphabetic cipher also known as an Quagmire IV by the ACA. An example would be here: Quagmire IV example and info (pardon the ads) I posses the IV key and the PT key. ...
0
votes
1answer
351 views

What is the most paranoid way to exchange messages? [closed]

I'm looking for a way for Alice to send a message or a file to Bob in the most paranoid way possible (over the internet). It can be asymmetric or symmetric. But According to some articles, AES ...
0
votes
1answer
1k views

Why the following attack in common modulus RSA works?

Suppose that i share a common modulus $N$ with two users $u_1$ and $u_2$ with public, secret keys ($e_a,d_a$), ($e_b,d_b$). Why then $gcd(V,e_b)=1$ where $V=d_a*e_a-1/$W and $W=gcd(e_b,d_a*e_a-1)$ ...
0
votes
1answer
264 views

Ways to protect flash player against MITM diffie hellman

We have a server, which sends content encrypted with AES128 or RC4 to a flash client over an insecure HTTP channel. The encryption key is negotiated using Diffie Hellman. The problem: Diffie ...
0
votes
1answer
193 views

RSA Signature - Multiple Use Weakness

I cite from Fundamentals of Computer Security (Chapter 7 on Digital Signature, Paragraph 7.3 on RSA Signatures, page 289): Multiple uses of the RSA Signature scheme tend to weaken it. The way out ...
0
votes
1answer
183 views

ECDSA - point order criterion

i am creating some primitive demostration for ECDSA over small curve (p < 229). But my implementation have some weird issues. Verify process return false even if the signature is correct. Because I ...
0
votes
1answer
242 views

How can we find Public key have only 8 or 16bits? How many messages does Eve need to know the Public key in RSA?

Suppose Alice sends messages to Bob by encrypting the messages with Bob's public key. Eve knows that the data is encrypted using RSA, but does not know the public key. Can Eve figure out the public ...
0
votes
1answer
275 views

Implementing Paillier Signature Scheme in Delphi

I've been trying to implement the Paillier Signature Scheme in Delphi, but I can't get it to work and I don't know where the problem is. First of all, I got my info about the scheme from this paper. ...
0
votes
0answers
19 views

What is the best authentication logic to analyze RFID (randomized hash-lock) authentication protocol?

What is the best authentication logic to analyze RFID (Randomized hash-lock) authentication protocol, (Ban logic, GNY logic, SVO logic, VO logic, AT logic) or another one?
0
votes
0answers
45 views

What would happen if we discovered a way to factor numbers with large prime factors?

If we somehow found a way to factor any number, no matter how large, into its prime factors in the matter of seconds, what would happen to the internet? What would happen to the electronic devices we ...
0
votes
0answers
14 views

how to use raw_input_file in dieharder , in binary mode (or decimal mode ) [on hold]

I have samples to be tested, they have fixed length , say N , N can be anything > 36. I want to input these samples as a file to test their randomness , I have one record per line eg : (...) ...
0
votes
0answers
34 views

AES mode scheme feedback [duplicate]

I've been studying encryption on a hobby basis, and wanted to know if I got this basic cypher construction right (this is another experiment, see the AES ECB experiment thread earlier). Encryption: ...
0
votes
0answers
11 views

Difference between Kerberos and GDOI? [migrated]

What is the difference between Kerberos and GDOI, I know first is more toward authentication and latter is more toward multicast key management, can I use Kerberose protocol in GDOI for server and ...
0
votes
1answer
38 views

DH and PKI for KeyExchange

My question is fairly simple. I have more than two nodes which needs to communicate very efficiently from computational point of view. One of the nodes can become a coordinator between the nodes. ...
0
votes
1answer
31 views

One-one correspondance complete function

I am reading the paper by John B. Kam and Georges I. Davida (1979) titled Structured Design of Substitution-Permutation Encryption Networks. On page 749 it reads ...
0
votes
0answers
31 views

Pseudorandom function and hash function [duplicate]

What is the difference between a pseudorandom function and hash function ? I have already read the answer in this link What is the difference between a hash function and a pseudorandom function? but ...
0
votes
0answers
17 views

Pre-Shared Key tunnel solution? [on hold]

I'm looking for program that will create an encrypted tunnel with port forwarding between two (linux) computers, that handles key exchange using a pre-shared password. In other words, something like ...
0
votes
0answers
26 views

BLAKE2 input parameters [migrated]

Being a newbie, I was reading papers on the recent crop of hash functions and BLAKE2 intrigued me. Then I wanted to play around with the "blake2s" code in the code package. If I were to implement a ...
0
votes
1answer
29 views

Would the Fiat Shamir identification scheme be more secure if I design it with an exponents higher than 2?

Let's say both Prover and Verifier would use nth power instead of 2nd when creating public keys and when verifying. I know it would slow it down but would that cause the protocol to be more secure?
0
votes
0answers
68 views

What do you think about this message encryption?

I am currently working on my diploma project, a high security NFC door lock and need to exchange very sensible data. That's why I thought of PGP encryption, which is as far as I know one of the ...
0
votes
0answers
19 views

Runtime of a particular step of karatsuba algorithm [closed]

I am new to algorithms and was trying to calculate the runtime cost of each step of the karatsuba algorithm. Assuming you know what the karatsuba algorithm is, So I was not sure of the calculation ...
0
votes
1answer
35 views

GCM implementation

I want to write GCM implementation myself (only for research purposes). So far, I have successfully written CTR implementation (for AES), but now I ran into few problems with GCM. If I'm not wrong, ...
0
votes
1answer
84 views

How does knowing the factorization of N can help to obtain the secret?

Assuming $x=a^2 \pmod n$ and knowing $x$, $p$, $q$ how is it possible to obtain $a$?
0
votes
1answer
30 views

Standard serialization format for libsodium-based messages

Does anyone know of a standardized serialization format which can be (or already is) widely used for encrypted messages? For a variety of reasons (mostly complexity, age and poor support across a lot ...
0
votes
0answers
16 views

PHP: How to show supported client ciphers [closed]

How to print a list of ciphers offered in ClientHello? How does e.g. mikestoolbox.org or hotaru.thinkindifferent.net show which cipher is used / offered by client? Thanks for helping.
0
votes
0answers
8 views

Acceptably secure solution for users to log in with a short unique code only (no username) [migrated]

I am creating a website whereby users are given an account by invitation only, and are sent a unique code by post. Users can then log in (at least the first time) by entering the code only. The goal ...
0
votes
0answers
39 views

What aspect of elliptic curve encryption paradigms makes them especially susceptible to quantum based attack algorithms?

This was a statement made during a talk at today's DFN-CERT conference but unfortunately it wasn't explained further. Can anyone shed light on why elliptic curves are susceptible to quantum based ...
0
votes
0answers
11 views

Getting Certificate KeyContainerName to initialize CspParameters [migrated]

How can I get the name of a Key Container that's in a smart card required for initialization of CspParameters? CspParameters^ cspa = gcnew CspParameters(ProviderType, ProviderName, keyContainerName, ...
0
votes
0answers
39 views

Is Fermat's Little Theorem possible over additive group? [migrated]

As Fermat's Little Theorem is define over multiplicative group $a^{p-1} \mod p$ = $1 \mod p$. Is there something over additive group?
0
votes
1answer
17 views

Linear Recurrence, keystreams, and periods

I am trying to understand the following problem: Consider the following linear recurrence over $Z_2$ of degree four: $z_{i+4} = (z_{i+3} + z_{i+2} + z_{i+1} + z_{i}) \bmod 2$ i >= 0. ...
0
votes
1answer
17 views

Hill Cipher the point of a known plaintext attack question

Is the point of a known plaintext attack on a Hill Cipher to get the matrix key?

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