1
vote
1answer
12 views

what are the plaintext's for the RC4 stream cipher test vectors in RFC6229?

https://tools.ietf.org/html/rfc6229 has stuff like this: ...
1
vote
0answers
17 views

What is the fixed point attribute of DES (when used with weak-keys)

I've heard in some lecture that the weak keys in DES implies the existence of $2^{32}$ fixed points in the algorithm, i.e. that $DES_k(x)=x$ for $2^{32}$ such $x$'s. I couldn't find anything about ...
0
votes
0answers
17 views

Signature verification with only hash (without full data)

I am looking for a way to sign a file, such that someone else can verify that I had this file, even if they only know a hash. I want to prove that I have the full file to someone who only has the ...
1
vote
0answers
35 views

The purpose of the final xor in Davies–Meyer scheme

In Davies–Meyer hash construction scheme each block is xor'ed with the previous block cipher text. Why? The only obvious flaw I see in a scheme without this xor is the possibility to reconstruct a ...
0
votes
0answers
25 views

Memory requirement in light weight block ciphers cryptanalysis

If we have a light weight block cipher where the block length is different than the key length. Let's say the block has a length of 64 bits while the key is 80 bits. For an attack to be successful, ...
1
vote
1answer
63 views

Attacker in a key exchange

I'm having trouble with the following question: $X(A) \rightarrow B:(A,N_X)$ $B \rightarrow X(S):(B,((A,N_X,T_B),K_{BS}),N_B)$ $X(A) \rightarrow B:(((A,N_X,T_B),K_{BS}),(N_B,N_X))$ ...
0
votes
0answers
31 views

vector space retrieval model

In tf-idf weighting scheme of vector space model, weight matrix is calculated as a product of term frequency(tf) and inverse domain frequency(idf). I need paillier dot product calculation here. Can ...
0
votes
0answers
8 views

How does SafeNet MobilePass calculate the counter for following passwords?

Original Question: How does SafeNet MobilePASS generate passwords? The algorithm to calculate passwords was implemented by the author of the original question here: ...
0
votes
0answers
37 views

how can I understand nonlinear coding for error detection

I want to understand how nonlinear coding can detect the errors in cryptography computing . actually I don't know what these code doing and what are the codewords in this system. now can any body ...
2
votes
1answer
45 views

Security of DES P_BOX

I'm curious about the design of the P_BOX of DES. I found a paper on this topic, but it dates back to 1989. This means the effect of p-box values of the cipher immunity against Differential ...
2
votes
1answer
56 views

Secure multiparty computation of conjunction

Suppose Alice and Bob each have bits a and b, respectively. How can Alice and Bob compute the function ...
1
vote
1answer
46 views

Perfect secrecy of a crypto system

Suppose we have the following crypto system: $P = C = K = \{0, 1, . . . , n − 1\}$, $E_k(x) = (x + k) \bmod n$ and $D_k(y) = (y − k) \bmod n$. Prove that the crytosystem has perfect secrecy. Perfect ...
3
votes
2answers
122 views

Does RSA operate over a Finite Field (Galois Field)?

Is it correct to say that RSA operates over a Finite Field (Galois Field)? In this case GF(p)? I do understant that the modulo in RSA is not itself a prime number, but all the operations ...
2
votes
1answer
53 views

Possible hashing scheme

Plaintext(binary) : 10101100 //very short for easy understanding Suppose we have 4 predefined schemes/functions, rotate (101 -> 011) flip (1101 -> 1011) exchange (11011 -> 10111) stretch (1100 -> ...
1
vote
1answer
22 views

How does SafeNet MobilePASS generate passwords? (TOTP Variant)

This question is similar to How does SafeNet MobilePASS generate passwords? The question and answer there is related to the HMAC Variant of SafeNet Mobilepass. I'm looking for details on the TOTP ...
13
votes
4answers
266 views

Why are primes important for encryption

Why are primes so important? Why can't we just use a random number? My guess is that it's because finding a random prime require more computing power, than finding a random number. Can anybody confirm ...
4
votes
1answer
87 views

Dancing confusion with Daniel J. Bernstein's stream ciphers

I know of Salsa20 which won the ESTREAM competition. This is dated of 25 Dec 2007. There is also the ChaCha20 stream cipher (cr.yp.to/chacha.html). This claims to increase the amount of diffusion ...
1
vote
1answer
72 views

one time pad regarding

If I had two ciphertexts $$c_1 = m_1 \oplus y_1 \text{ and } c_2 = m_2 \oplus y_2$$ will it be possible to obtain $$z_1= (m_1 \lor m_2) \oplus y_1 \oplus y_2 \text{ and } z_2= (m_1 \land m_2) ...
7
votes
1answer
149 views

Why is authenticated CFB mode insecure?

I read that the following adaptation of the CFB block cipher mode into an authenticated mode is prone to chosen plaintext attacks, yet Im still unsure how to prove it: Let $P_1,P_2,\ldots P_n$ be the ...
2
votes
1answer
47 views

Build set with PKI from reliable broadcast / random beacon

I am trying to build a protocol (or find an existing one) for creating a set $S_2$ with PKI from a set of parties $S_1$ that initially does not know anything about the other parties. We assume ...
-2
votes
0answers
44 views

Encryption key input by a user [on hold]

I was looking for some research papers where the security scheme is using 'user input' key method (but could not find). I mean, some approaches where user will be the one who will put keys for ...
4
votes
2answers
205 views

Extending pseudorandom generator by one bit using exclusive-or of previous bits

Is it possible to have a pseudorandom generator that extends its output by 1 bit by simply appending the exclusive-or of all the previous bits? I know the output of a pseudorandom generator is ...
2
votes
1answer
47 views

How do we find the subkey out of a differential cryptanalysis?

I understand the differential cryptanalysis up to the "finding the last subkey" part. If XORing with the key doesn't change the differentials, how can testing different key affect the equations we ...
0
votes
0answers
5 views

How to replicate GPA's Sign and Compress option on command line in Windows [migrated]

As the title says, I need to replicate GPA's "Sign and Compress" option on the command line. I'm trying to automate some encryption of files for submission to a bank and the instructions they gave me ...
0
votes
1answer
62 views

“Kernel attack” on MinRank — why do we guess $\left\lceil \frac k n \right\rceil$ vectors?

The kernel attack on MinRank is described here (page 5). My question refers to this line: Note that if $m = \left\lceil \frac k n \right\rceil$, the system essentially has only one solution ...
-2
votes
0answers
38 views

Is cm signed signature verification considered “slow”

I put slow in double quotes because I'm no expert in encryption (I heard that "cryptography in general is inherently slow"). Just trying to gauge and see how and where I can increase performance of my ...
5
votes
3answers
380 views

What is the difference between uniformly and at random in crypto definitions?

Very often in the description and analysis of a cryptographic protocol there is a need for a an element $k$ that is sampled uniformly AND at random. Is there a redundancy in the definition with ...
0
votes
0answers
30 views

request for data to test deterministic ecdsa signature algorithm for secp256k1

I’m implementing the RFC 6979 procedure to compute a message signature. I want to test my program on the secp256k1 elliptic curve. Note the “k” in secp256k1, i.e. the Koblitz curve. If you have the ...
2
votes
1answer
130 views

How to customize a standard encryption algorithm?

I want to modify and customize AES encryption algorithm and develop a variant of it. What factors should I consider so that it does not become weaker? What skill sets would be required to undertake ...
1
vote
1answer
68 views

Malleability of homomorphic encryption

El Gamal is a malleable homomorphic encryption system, so is Rabin. Are all homomorphic encryption systems malleable? Or are there any that are not malleable? Thanks!
0
votes
0answers
31 views

electronic voting system [migrated]

Was looking at cryptocurrency and how, as a non techy, to get involved when I began thinking about the security of it being developed to undermine the stranglehold bankers have on economy and the ...
-2
votes
1answer
64 views

Starting an essay on cryptography, 1st year college [closed]

I'm starting an essay on cryptography for my computer science class. I don't really know where to start so I wonder if there are some pre-made stuff for beginners that are explaining what cryptology ...
0
votes
2answers
154 views

What would be the best plain text Cryptography method without the use of a computer? [on hold]

What would be the best Cryptography method without the use of a computer? This could be a list of the current options available, that could be used without the use of a computer ...
-2
votes
0answers
25 views

Verifiable random function basic example [on hold]

I've decided to take a closer look at verifiable random functions. The concept is clear for me, but I'm looking for an easy-to-understand example for my presentation's original definition. So, in ...
1
vote
1answer
61 views

Polynomial division hardware implementation

I am beginning the implementation of the polynomial binary division algorithm now as I understood i will be checking the MSB bit if 1 to XOR and shift the sum if 0 i will only shift. What I am not ...
-1
votes
0answers
36 views

What is a good way to program the finding the determinant of a 2x2 matrix? [migrated]

I have a good understanding of how to do the Hill cipher on paper but putting it into program form is somewhat of a problem. Finding the the determinant is the thing I'm having problem with. On ...
1
vote
1answer
51 views

RSA Protocol behind Yaksha Security System

So I'm reading over the Yaksha Security System and see it is based on the RSA cryptosystem and a centralized server, easy enough. What I'm slightly confused on is the math behind the related keys. It ...
-1
votes
0answers
46 views

Security considerations on using key derivation to create one-time keys for block ciphers

I'm planning to do some block encryption with AES and Blowfish (both with 256 Bit keys) chained. Master key generation: A 32 byte long persistent (over many years) master key is derived from a ...
-2
votes
0answers
26 views

Decrypting a long message with RSA [closed]

This is the question: ...
1
vote
1answer
85 views

N way collision of hashes

For a collision $H(A_1) = H(A_2)$, the number of queries is $T^{1/2}$ where $\log_2(T)$ is length of hash output. Then, what would be the number of queries requried to find an $n$-collision ($H(A_1) = ...
0
votes
0answers
24 views

How to determine which key derivation function used for password?

Suppose an attacker collected a password hash file. After performing rainbow tables/dictionary attacks they choose brute force attacks. So they try guessing as many passwords as they can by running ...
0
votes
0answers
17 views

Generate CA with aes256 passphrase protected DSA key

I want to create my own Certificate Authority with an DSA key. I figured out to create it with: ...
0
votes
1answer
60 views

Bae64 with shuffled alphabet

I have a base64 'cipher' text, I know that in clear text is a hidden xml document (I do not know nothing about its structure), but the base64 aplhabet was somehow shuffled. Is there any smart way, how ...
0
votes
1answer
52 views

Looking for a secure PRNG that I can implement in hardware

I'm trying to implement a (sort of) simple PRNG in hardware for fun. My idea would be to allow a user to enter a key using a keypad (or some dip switch settings that can be set and hidden) and to ...
-2
votes
0answers
31 views

Best steganography/alysis practice for total beginner [on hold]

Which method would be more beneficial to learning: A. Create my own labs by creating my own steganograms, analyzing them too look for the pattern changes etc. or B. Seek out pre-existing files where ...
0
votes
0answers
72 views

How do I find a random BigInteger smaller than another random BigInteger? [migrated]

How do I Select a random element α ∈ Z∗p? P is a random 1024 bit prime BigInteger. Here is how I find BigInteger p: ...
1
vote
1answer
76 views

Is it safe to AES-CBC and AES-CMAC both using the same key?

There is a very similar question (Using a derived key for CMAC) but it doesn't quite answer this one (at least for me it does not). I have a situation where I need to transfer some data. My data has ...
1
vote
1answer
63 views

Why do we have fixed output length in the algorithm SHA1

Why do we have fixed output length in the algorithm SHA1 . is there any explanation about that
1
vote
1answer
48 views

RSA-blind signatures vs. DSA-blind signatures

I see that the RSA blind signature scheme tends to be implemented more often than others, e.g., DSA blind signatures. Isn't the RSA blind signature scheme a 'lesser' scheme, if you may, compared to ...
1
vote
0answers
55 views

How does Schnorr signature actually work?

I'm trying to get a grip on how Schnorr signature works. Suppose Alice sends Trent a tuple $(P, M)$, which contains a payload and a message to be signed by him. She then passes the certificate to Bob ...

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