All Questions

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0answers
1 views

How to do Client SSL Authentication using a USB security token?

Firefox has ability to import pfx files (containing certificates and private keys) & use imported certificates in a two-side SSL. Now I've a certificate & its corresponding private key in a ...
0
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0answers
4 views

Continued Use of Kerebos

I'm not entirely sure this is the correct forum, as opposed to Security.SE, so if someone wants to migrate it over I have no complaint. I was recently looking through the Mac OS X 10.10 source code ...
0
votes
1answer
17 views

What, cryptographically speaking, is a “long message”?

I have read about long message attacks on some cryptographic hash functions. However, I don't quite understand what is being referred to as a "long message". Also, do long message attacks only apply ...
0
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1answer
6 views

CRC32 vs. low 32 bits of cryptographic hash

I was having a discussion with a colleague yesterday whose education and experience exceeded mine. He said something yesterday that sounded incorrect to me intuitively, but I don't have the knowledge ...
0
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1answer
9 views

what is contained in a public key certificate

Public key certificate is a digitally signed document which verifies the sender is indeed the person. May I know how can the receiver tell the sender is indeed the person solely based on information ...
0
votes
1answer
15 views

Simplest code for 64-bit block RSA-like encryption/decryption and key generation

Looking for the simplest code in C. Need a set of functions that will first generate a public/private 64-bit key pair, and then the function to code/decode a given 64-bit block, no built-in checksum ...
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0answers
25 views

Is storing HMAC key in a key file safe?

In an encryption implementation, a key file contains a header with some information required by the encryption algorithm, (mode, engine, padding etc.), and an amount of p-rand used for key and vector. ...
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0answers
17 views

Type of cipher used where ciphertext has no discernible pattern, spaces. Type?

What type of cipher could give ciphertext where for example random ASCII chars between say F-z (symbols and numerals inclusive), but with only a few spaces? Frequency of chars shows some similarities ...
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0answers
17 views

signed message susceptible to block re-ordering , block deletion , block replication

We would implement a Public Key Cryptography (PKC) based digital signature by breaking the message into blocks and signing each block independently. One of the issues associated with digital ...
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0answers
15 views

CBC MAC forging

Could someone please explain how one can forge a MAC in the following scenario :Suppose Alice is using CBC-MAC with AES-128 is used and decides to change the IV for every message
-1
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0answers
10 views

?, software/hardware solution(s) for encrypt/decrypt of NAS(s)/SAN(s) that vary in size. LUNs are 4tb+ [migrated]

well hello newbie..first of...with truecrypt & bitlocker totally out of the question (the security issues), what software solution would you recommended to be used to encrypt/decrypt (on the fly ...
1
vote
1answer
60 views

RSA Decryption given n, e, and phi(n)

my cryptography professor gave us this problem for extra credit a while back and I attempted it but I didn't get it correct. I have gone back to it, but I'm even more lost now than I was the first ...
1
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1answer
53 views

AES— Brute force attack versus Known plain text attack

I am taking a codes and cryptology course and the following is a questions on a past exam that I could not and still can't solve: ...
1
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0answers
46 views

Why is it hard to calculate Logarithm on Diffie Hellman?

i read something about Diffie Hellman. What i don't understand: Alice selects a randomly generated Number, calculates X = g^x mod p and sends X to Bob. If she calculates g^x, she needs to calcluate ...
-1
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0answers
35 views

How to add our created session encryption algorithm to (major) browser using OpenSSL [migrated]

I am new to OpenSSL and have theoretical information in SSL protocol . I have task to create a certificate who uses RSA algorithm for symmetric session key exchange and use my own my encryption ...
0
votes
1answer
23 views

RSA signature scheme

In RSA signature scheme, it is a common practice to 'sign' the hash value of the message so that the length can be fit. Question: If we have $s=m^d \bmod n$ where $d$ satisfies $ed \equiv 1 ...
1
vote
1answer
41 views

Are there any digital signature algorithms in common use that result in 32-byte signatures?

I don't consider myself to be an expert in this field, so forgive me if there is an obvious answer. I am having a tough time finding an algorithm that can sign data and output a 32-byte signature, ...
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0answers
33 views

Low exponent attack against RSA

According to this: http://www.cims.nyu.edu/~regev/teaching/lattices_fall_2004/ln/rsa.pdf One can calculate the message m, if there was no padding scheme involved. My question: is it possible to find ...
0
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1answer
28 views

Symmetric vs non-symmetric pairing based crypto

I am trying to find a comparison of how different pairing-friendly elliptic curves perform (in terms of security) in real world applications; I am using PBC library, and it has type A curves and type ...
0
votes
1answer
50 views

Why develop new stream ciphers when block ciphers can be trivally made into streams?

I've just been reading about a new drop-in replacement for the RC4 stream cipher, but why develop new stream ciphers when AES can be made into a stream with a little XORing?
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0answers
14 views

Help in uderstanding NIZKPoK notation (and how to code it) needed

Hello fellow cryptographers I have a rather silly question for you; I am aware of how Schnorrs NIZKPoK / SoK works when someone must prove knowledge about DL: y = g^x; (and how to code it) RFC ...
1
vote
1answer
19 views

Is equal length of primes in Paillier cryptosystem is mandate for security reasons?

In continuation to this question about length of primes , I am in doubt about the restriction on length of primes itself . In Paillier cryptosystem , equal length of primes are used . My doubt is ...
1
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0answers
37 views

DLOG in $\mathbb{F}_{p^n}^*$?

Assume that we are given an element $g\in \mathbb{F}_{p^n}^*$ and $g$ does not belong to any of the smaller subfields contained in $\mathbb{F}_{p^n}$. If the degree of $g$ is some number $q$, how much ...
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0answers
53 views

Serpent 256bit Non bit sliced version (Table Sbox/IP/FP/LT/ILT)

Good afternoon! I got some mismatches while counting Round Keys at non bitsliced version of Serpent. I have used official AES submission outputs (file ecb_iv.txt). AES submission package test vector: ...
0
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0answers
39 views

Public key encryption without ciphertext expansion

Say I have a database column that is defined as VARCHAR(255) that stores names. I can assume that names can be up to 255 chars. I need a public key encryption so that I can replace names with their ...
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0answers
29 views

Password generation/storage scheme

How bad is the following strategy for a password manager on a local machine? The user wants to sign up for somesite.com where he needs a password. The user has previously generated a secret key ...
0
votes
1answer
21 views

Direct sum of Binary numbers In Mixcolumns

I have just started learning cryptography and I am trying to make sense of the direct sum on some binary numbers. I am trying to find a column of a state space after a Mixcolumns operation has been ...
1
vote
2answers
58 views

Encrypting twice with same key gives back plain text

I read in the answer here that when encrypting twice the plain text with same key could result in plain text as shown below $encrypt_{key}((encrypt_{key}(plain)) = plain $ Which block-cipher ...
1
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0answers
55 views

What are SNARKs?

What does it mean and what is it used for, I have been hearing this term a lot lately. From the context I've heard it talked about it seems to be connected with zero knowledge?
1
vote
1answer
61 views

How can a good pseudo-random number genarator be made?

I am trying to make a pseudo-random number genarator so that I can use it in a synchronous stream cipher for encrypting plain text. I want it to genarate numbers which are as random as possible. Can ...
2
votes
1answer
85 views

What are these twist attacks with cost $2^{58.4}$ on NIST P-224 curve, and when do they apply?

This page on Twist security mentions a combined attack and a twist rho attack, applicable in particular to NIST P-224 curve with cost $2^{58.4}$ something, with no mention precise definition of ...
4
votes
1answer
70 views

Understanding Twist Security with respect to short Weierstrass curves

I'm trying to understand the "Invalid-curve attacks against ladders" section of SafeCurves Twist Security page and I have difficulties to apply it to short Weierstrass curves. That section claims ...
0
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0answers
22 views

Elliptic Curves Readdition

I found the term re-addition in https://www.hyperelliptic.org/EFD/g1p/auto-shortw-projective.html and I cannot figure out what it is. It has actually same complexity of addition and I dont see the ...
1
vote
1answer
74 views

Why does openssl use SHA1 in ECC when I use secp384r1 curve

I need a small clarification that why openssl using SHA1 in ECC when I am using secp384r1 curve, but in rfc they are saying we should use SHA2. Thing here is am using nanoECC in my DTLS, nanoECC ...
0
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2answers
101 views

Encryption algorithm designed to be easy to decrypt by machine but impractical to decrypt by hand

I am looking for - or considering the design of a new - encryption algorithm that does not use variable keys, such that it is easy for a computer to encrypt and decrypt any message regardless of its ...
1
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0answers
51 views

About the Algebraic Normal Form (ANF) of S-Box in DES

I've thought up a way to represent the transformation of S-Box in DES by ANF. Let $x_i\;(1\le i\le 6)$ be the input of an S-Box, $y_i\;(1\le i\le 4)$ be the output, for example, then $$y_1= 1\oplus ...
1
vote
1answer
30 views

A simple attack on DESX in time $2^{120}$

Let $\mathcal{M}$ be our message space and $\mathcal{K}$ our key space. Now, let $\mathrm{E} : \mathcal{K} \times \mathcal{M} \to \mathcal{M}$ be a block cipher. Define the block cipher ...
3
votes
1answer
59 views

Why does NTRUEncrypt lack a formal security proof?

Is there any particular reason why NTRUEncrypt lacks a formal security proof? That is, a demonstration that it achieves certain security notion (e.g. IND-CPA). I know there is a provable-secure ...
0
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2answers
58 views

public key certificate on TLS/SSL

Currently I am working on a public key certificate. I got a question: Why is a public key certificate needed for TLS/SSL? Wouldn't TLS/SSL itself is enough? What is the role of the certificate?
0
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1answer
46 views

rsa public and private keys

I have a question about RSA key generation: this is a simple rsa algorithm: Choose p = 3 and q = 11 Compute n = p * q = 3 * 11 = 33 Compute ?(n) = (p - 1) * (q - 1) = 2 * 10 = 20 Choose e such that 1 ...
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0answers
66 views

Why cbc-mac is a secure mac with psudo-random but not random IV?

Is cbc-mac a secure mac with pseudo-random function? If it is yes, Anyone can prove that? Also, is it based on the length of key? BUT why is not secure with a random IV?
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0answers
49 views

What can we say about x, y if B is prime, semiprime or even number? [on hold]

I have found method for integer factorization, where we are trying to find x,y. Let us emphasize two cases: a) Let $N=ab$, $b<a$ and $N\equiv 3(\textrm{mod }4)$ if we take $B=\frac{N+1}{4}$ ...
1
vote
2answers
91 views

RSA prove $a^{\varphi(n)/g} \equiv 1 \pmod{n}$

I should prove that $a^{\varphi(n)/g} \equiv 1 \pmod{n}$, so I thought I would prove it with primitive roots but I got stuck. Here is the assignment: Let $p, q$ be primes such that $p \ne q$. ...
0
votes
1answer
73 views

RSA CRT modulo reduction

I am working on RSA CRT and there is a point that I don't understand : So we have $n=pq$ and $c = m^e \bmod n$ an encrypted message. To decrypt $c$ with RSA CRT, we have to compute : $d_p = d \bmod ...
1
vote
1answer
60 views

Are there any many to one encryption frameworks available?

I am reasonably new to the cryptography. For my use-case I need a method where in I would need a receiver to accept encrypted messages from a range of senders (each having their own, say, public key). ...
2
votes
1answer
106 views

The Boneh-DeMillo-Lipton fault attack (RSA CRT)

I am trying to understand the Boneh-DeMillo-Lipton fault attack on RSA CRT signature. Suppose that we sign a message $m$ with RSA-CRT : $d_p = d \bmod (p-1)$ and $d_q = d \bmod (q-1)$ $s_p = ...
2
votes
2answers
111 views

What is a q-type assumption?

I've seen the term "$q$-type assumption" used in a few papers without a definition. A google search doesn't seem to come up with anything useful either (except the same papers without a definition). ...
0
votes
1answer
54 views

Client-server communication

The base scenario goes as follows: A program stores some user's confidential data encrypted on their disk. The user is most probably clueless and the disk might get stolen, but these are the classical ...
0
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0answers
122 views

Cryptographic Dilemma [on hold]

I'm reading an article where they are talking about 'the Cryptographic Dilemma. Is there one universal dilemma in cryptography? I can think of a few, like computation time vs. crackability. The ...
-1
votes
0answers
50 views

What is a vanishing trapdoor?

Explain like I'm five. The term is mentioned here: http://bristolcrypto.blogspot.se/2014/10/this-weeks-study-group-was-given-by.html

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