All Questions

0
votes
2answers
41 views

Perfect secrecy and known ciphertext length

From what I understand perfect secrecy means that the probability distribution of the messages are independent of the cipertext, right? How can the one time-pad be perfectly secret when the ciphertext ...
-2
votes
0answers
39 views

Libsodium not decrypting AES-256-GCM [on hold]

I posted this question earlier but it was moved as it was deemed a programming question but I don't think it is. I think it's me not understanding how AES-256-GCM decryption works. I'm trying to ...
-1
votes
0answers
22 views

Boneh-Franklin Identity-based encryption scheme [on hold]

Could you please explain to me the for algorithms used in Boneh-Franklin identity-based encryption scheme. These algorithms include setup, extract, encrypt and decrypt. For example in the setup ...
1
vote
1answer
81 views

Where do the constants for SHA-1/2/3 come from?

My request is: I need to know the source of constants (shift constants, IV, or S-Box) for the following algorithms: SHA-1 SHA-2 (all sizes) SHA-3 Examples: BLOWFISH uses the hexadecimal ...
0
votes
0answers
4 views

Libsodium decryption returns empty response [migrated]

I can't get Libsodium to decrypt a response I'm receiving from a webhook but openssl_decrypt does. I'm not getting an error but I keep getting a blank result which ...
1
vote
2answers
88 views

Verify partial message given hash of full message

I need to verify partial downloads (retrieved sequentially), given a (preferably short) hash of the complete download. Given a message $m_0 \mathbin\| m_1 \mathbin\| m_2 \mathbin\| \cdots$, hash ...
0
votes
0answers
41 views

Can I use XOR to establish a longer shared secret?

SIKEp434 can only be used to encapsulate a 16 byte (128 bit) shared secret key. Most encryption algorithms these days (specifically (X)ChaCha20) require a 256 bit key to be secure, especially in a ...
-1
votes
0answers
22 views

Post quantum TLS based web-browser client [migrated]

Are there any open source projects that implement a web browser client that has support for post quantum TLS protocols so that it can talk with post quantum patched TLS web servers. I've checked ...
0
votes
2answers
97 views

Why is prime number size important for RSA security?

RSA modulus is $N = pq$ where $p$ and $q$ are prime numbers. I read from somewhere that the time it takes to decrypt the RSA encryption increases exponentially as key length increases, which depends ...
-2
votes
0answers
27 views

How to prevent HR forwarding or downloading or printing my Resume? or let the email destroy itself after a time limit? [closed]

I have a bad feeling sending my Resumes to different companies and I think they will save my data. Is there a way to encrypt my Resume? Can I let it destroy itself after a certain time limit? Or just ...
0
votes
1answer
78 views

What is “spinal-tap grade” security?

As stated here Ed448 is different from Ed25519 because of "spinal-tap grade" security. What does this mean?
3
votes
1answer
87 views

Induction is problematic in computational cryptography - Why?

In Dr. Lindell's lecture The Yao Construction and its Proof Of Security, in briefly explaining the hybrid argument, he makes the statement that mathematical induction is a problem in computational ...
2
votes
3answers
150 views

Does the use of English words weaken diceware passphrases

A Diceware passphrase is constructed from a set of words chosen from a 7776-word database, using five dice throws to choose each word. The argument is that each word in the phrase adds about 12.92 ...
0
votes
1answer
123 views

What's the number of unique possible Cayley tables in a 16*16 grid for XOR'ing single hex characters? [on hold]

A few days ago, I designed and s-box then derived the following Cayley table of all possible XOR outputs of hex digits in the range of ${2^4}$ and was curious how many such "valid" possible ...
0
votes
1answer
52 views

Why does Hasse's theorem sometimes seem to be invalid?

In order to generate secure elliptic curves, this answer recommends to Calculate the cardinal $|E(\mathbb{F}_p)|$ Check this cardinal is in the hasse interval (with $p$ prime) and to ...
0
votes
0answers
18 views

integrity and non-repudiation on logs [closed]

If I want to send log files of total 100M and 10M per each file. I want to maintain the integrity and non-repudation for 5 years atleast. And the system on the client side doesn't have a high ...
1
vote
2answers
63 views

OTP with fixed plaintext

I have just learned about the OTP, how it uses XOR, and how it's secure if the keys are random. But what will happen when the same plaintext is used again with a new key? $c_1 = k_1 ⊕ p$ $c_2 = k_2 ...
2
votes
2answers
56 views

Hardwired secret key in public/ private key encryption

I am new to cryptography and I need to know some details about the hardwired keys. Taking as an example multi-input functional encryption 1, a key is hardwired in the description of the key ...
0
votes
0answers
25 views

Method for getting encryption keys from U2F key

There are a number of questions on this site about how/can you use a U2F key to encrypt something. The main problems with doing this are that U2F keys were designed for authentication, so all they can ...
-1
votes
0answers
25 views

Hill Cipher cryptanalysis unknown key size [closed]

I have the plaintext CONVERSATION which is encoded as SQZHUSSUDYKP, standart alphabet is used(A=0,B=1,...). I have no information about the key and I must find it.
15
votes
3answers
3k views

Digital signature that is only verifiable by one specific person

I would like to digitally sign a message in such a way that the signature can only be verified by one specific person. Simply encrypting the signature will not work, because that person could then ...
1
vote
0answers
67 views

Randomness Test of Permuted Sequence

As we can generate a permuted sequence using KEY in KSA (Key Scheduling Algo) of RC4. Is there any way to check the randomness of the permuted sequence? Let say I created 100 different permuted ...
0
votes
0answers
32 views

Identifying the exact encryption procedure by database hash

I was asked to develop an external user administration for a legacy system so that it could be integrated into company processes. This system is mostly written in Python, but also uses unmanaged DLLs. ...
1
vote
0answers
24 views

Side channel attack: Why building an eviction set is possible?

I'm learning about the side channel attack on the cache. I came to know that most of the attack (EVICT + TIME, PRIME + PROBE, PRIME + ABORT) on the cache is initiated by building an eviction set(a ...
-1
votes
0answers
36 views

binary bit shift [closed]

I'm studying for my exam and we have to perform a bit shift on binary. For example: 1110 0010 0011 1100 and we have to shift it to the left 9 places The only thing I found online to help me was to ...
0
votes
0answers
18 views

Function-hiding functional encryption with simulation-based security

I have been reading the paper "Function-Hiding Inner Product Encryption is Practical(https://eprint.iacr.org/2016/440.pdf)". There is a definition for function-hiding inner product functional ...
1
vote
1answer
26 views

Randomization attack in voting protocols

I'm looking into coercion-resistant voting schemes and one of the key elements of coercion-resistance is resistance to randomization attacks. Juels et al. define a randomization attack as one where ...
6
votes
0answers
94 views

RSA factorization with special primes

Suppose that primes for RSA modulus are generated using formula: $P_i(x,y) = \operatorname{next\_prime}(x^{z_i}+y^{z_i}) = x^{z_i}+y^{z_i}+d_i$ where $x,y$ are unknown random numbers with size 128 ...
0
votes
0answers
36 views

Unknown three part signature [migrated]

I have received a string which is supposed to be a cryptographic signature. I have access to a certificate which should let me verify the signature. However, I am rather confused about the structure ...
1
vote
0answers
49 views

What can be said about the self-power map on groups based on DLP?

I've been playing with group representation theory some time, concretely representing groups as permutation groups (Cayley's theorem), where the group $G$ has an embedding into the symmetric group. ...
0
votes
0answers
22 views
0
votes
0answers
38 views

Why do Browsers in their TLS1.3 Client Hello do not request for CCM ciphers? [migrated]

As per TLS 1.3 RFC 8846, following 5 ciphers are supported. ...
4
votes
1answer
32 views

Is verification of ring signature always linear in the amount of members?

To me it seems that maybe we can prove that verification of a ring signature must be linear in the number of members, since we need to make sure each members component is correct and the ring is ...
0
votes
1answer
53 views

Given $P=xG$, prove in zero knowledge that I know $sqrt(x)$

Assuming that x has a sqrt. Given $P=xG$ is it possible to prove that I know the $sqrt(x)$ in zero knowledge?
1
vote
1answer
39 views

Given A, B, G, H prove the I know x s.t. $A=xG$ and $B=xH$

Given A, B, G, H .How would I prove that I know x such that $A=xG$ and $B=xH$
0
votes
0answers
30 views

Prove I know only $a$ in $P=aG+bH+cQ$

Given a pedersen commitment $P$, is it possible to show that I only know $a$ in $P=aG + bH + cQ$ in zero knowledge
0
votes
1answer
36 views

Probabilistic verification of signature schemes like RSA?

I was wondering if there were any verification algorithm in the literature that enables a "probabilistic" verification of well-known signature schemes? For RSA signature verification for example, is ...
0
votes
0answers
37 views

Two parties looking to share data anonymously

I've been struggling to find good info on how to do the following: A(lice) and B(ob) each have a table of data (a and b ...
0
votes
0answers
61 views

Construct an adversary [closed]

Fix $N$, $e$ with $\text{gcd}(e, \phi(N))$ = 1, and assume there is an adversary $A$ running in time $t$ for which $Pr[A([x^e \mod N]) = x] = 0.01$, where the probability is taken over uniform choice ...
0
votes
0answers
13 views

How should I generate a CSR to get my personal email's key pair be verified? [migrated]

So I'm currently looking to get my public/private key pair that I use to sign emails to get verified by SwissSign, and the service requires me to provide a CSR. So my first question is how should I ...
2
votes
1answer
33 views

Can HKDF be instantiated with HMAC-SWIFFT?

While reading through "Cryptographic Extraction and Key Derivation: The HKDF Scheme" by Hugo Krawczyk, I found the following text intriguing: In some cases, well-defined combinatorial assumptions ...
0
votes
0answers
16 views

What is the difference between these pairings classifications?

I know the basic definitions of bilinear groups. For example, there is a bilinear pairing that uses elliptic curves and has the following properties: For $G_1$, and $G_2$ are cyclic groups of prime ...
4
votes
1answer
85 views

Elliptic Curve Cryptography insecure when input does not lie on the curve?

I am new to Elliptic Curve Cryptography and I was reading up on it online when I came across this link. It stated the following. Unfortunately, there is a gap between ECDLP difficulty and ECC ...
-1
votes
0answers
28 views

Maple code for Decryption using RSA [closed]

i am given a ciphertext 596912 along with n = 823091 and the private key e=17. is there a maple code that i can use to decrypt the ciphertext since i'm not given the value of d, p and q?
0
votes
1answer
30 views

Reasoning about WebCrypto ECDSA choices: P-256/384/521, SHA-1/256/384/512?

When implementing EC signing/verification in Javascript, the only options available via the WebCrypto API are: Curves: P-256, P-384, or P-521 Hashes: SHA-1, SHA-256, SHA-384, or SHA-512 If I was ...
0
votes
1answer
33 views

Choice of delta-neighbors in Balloon Hash algorithm

Reference Document: https://eprint.iacr.org/2016/027.pdf According to appendix D section 4 definition 27 each vertex in V has predecessors sampled independently and uniformly at random from the ...
1
vote
1answer
54 views

Enigma rotation example

According to wikipedia: BDZGO is the expected outcome when doing the enigma chipher on the letters AAAAA with rotors I,II,III and reflector B. ...
2
votes
2answers
99 views

What is the difference between the adversary and the algorithm?

I recently saw a sketch relating to provable security in a book, regarding the amount of time it takes to factor N where N = pq and p,q are primes. It says that "There is a trivial algorithm which ...
0
votes
0answers
22 views

TPM Key Attestation with ECDSA keys [on hold]

TPM 2.0, at least in Windows 10, seem only able to perform TPM Key Attestation for RSA-based keys. Is this a hardware limitation of the TPM 2.0 chips or a limitation of Windows 10?
0
votes
0answers
43 views

Reduction to security of proof system for proving knowledge

I want to prove security of my system by reduction to the security of an underlying non-interactive proof system for proving knowledge. I know a game that captures the desired security property of my ...

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