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End-to-end encrypted web services (like cryptpad) often include a 128-bit seed in the hash part of the URL (that is not sent to the server), to derive both an identifier that is sent to the server, and the encryption key that is used on client-side only. This seed allows shorter URLs than storing both the identifier an... |
Is there any proof that guarantees that a password with specified features (eg. with random special characters, combination of numbers & letters, some length etc) is secure? If there is such a proof, can you provide it or a link to it?
Edit: I am looking for formal proof, argument of theory that backs the choice of pas... |
In LWE based multi party FHE schemes, the parties should choose a much larger noise when perform joint decryption. In this paper, the author just said that using noise flooding technique to avoid the information leakage about the noise of the ciphertext. Then, how should we choose the smudging noise in a real scenario？... |
I' following along the book "Realworld Cryptography", in chapter 9 where the TLS protocol is introduced, they mention:
Following [authentication], the server can use its certified long-term key pair to sign all handshake messages that have been received and previously sent in what is called a CertificateVerify message... |
First of all, I'm not an expert or even a novice in Cryptography.
I mean this has certainly been implemented by some scummy PRNG developers, which thought of the economics behind it (especially in the casino and similar businesses where the biased distributions would interest people to play from the start but in the lo... |
A supplier is sending me very private information. For security, we are using thedecryptor.com website to encrypt the message. The website provides public and private keys.
We agreed that he will sends me a public key before payment, and a private key after payment.
I would like to know if it is possible to change the ... |
Everyone knows Argon2id is a slow hashing algorithm, and that's on purpose, all is good.
When creating an Argon2id object a lot of parameters are needed to be taken into consideration ultimately settling on a configuration that is strong enough but within the amount of time that you're willing to wait for the operation... |
If there is a uniformly random 128-bit private key scalar $x$, with the corresponding public key $X=xG$ (where $G$ is a well-known base point), how difficult would it be to discover $x$ from $X$?
I am aware that the regular approach would be to use a KDF to derive a private key in the range of the group size of the bas... |
As we know every x value has two y values which are reversed. Just by having the public key, is there a way to determine which side the y value is?
My first approach was to check if the y value is odd or even but after creating many public keys with different secret keys, I didn't find any pattern to check if the y is... |
Out of interest I wanted to test the results of using a floating analogue pin on my Arduino to generate a sequence of random numbers using dieharder.
My working assumption was that it would be a poor source of random numbers and would fail many of the dieharder tests.
I used the following simple code on the Arduino and... |
Let $F$ be a PRF such that $|F(k,x)|=2n$ show that $F_2$ isn't a PRF. Let's assume $F(k,x)=(y_1,...,y_{2n})$ then $F_2(k,x)=(y_1\land y_2,...,y_{2n-1}\land y_{2n})$.
I want to prove $F_2$ isn't a PRF but not sure where to start from since I don't really know much about $F$.
I thought about looking how many 0's are ther... |
This article from Wikipedia claims that "256- and 320-bit versions of RIPEMD provide the same level of security as RIPEMD-128 and RIPEMD-160, respectively".
Is that true or false ? And why ?
|
How good from a randomness point of view are recursively generated sequences using good encryption algorithms?
Let us say I take AES128 which generates good random sequences of outputs for counter inputs. Denote C=E(K,P) to be the output of AES128 with symmetric key K and input block P. Consider the recursively generat... |
I'm studying ECC, so this is focused on elliptic curves over finite fields. I've always seen the quadratic twist $E'$ of an elliptic curve $E$ defined as the elliptic curve with equation $dy^2=x^3 + ax + b$ for some quadratic non-residue $d$. Not a quadratic twist but the. Does this mean that there's some sort of equiv... |
OpenPGP defines RSA secret key in a way which differs from PKCS #1,having the aforementioned values plus U = P^-1 mod Q.
However, OpenSSL seems to work only with (N, E, D) or (N, E, D, P, Q, dP, dQ, qInv) where last three should satisfy the following (as from PKCS #1):
e * dP == 1 (mod (p-1))
e * dQ == 1 (mod (q-1))
q ... |
TL:DR
How can I give a population of N people the chance to randomly pick one token each person guaranteeing those:
Nobody knows noone else's token.
Noone can pick more than one token.
Every person may choose to pick a token or not.
So for N people, after the time window there are M picked tokens and N-M tokens left ... |
Blake2(1024 bit state) permutation (compression function core) is basically a modified ChaCha permutation. One of the modifications is to mix in message bits (key schedule?). Given that blake2 is a hash function, designed to resist related messages (related key attack?) would it not also make a good 1024 bit block ciph... |
Is XChaCha20 with 256 bit key and 192 bit nonce more secure than 128 bit key 128 bit key nonce AES, due to using larger key/nonce sizes? Isn't it supposed to be faster due to being a stream cipher? (in my implementation in turned out to be faster)
Any documentation or sources for further guidance? Thanks
|
There is a plethora of elliptic curves that are close to the 256-bit security level (i.e., fields and groups of approximately 512 bits). Examples are Curve448, P-521, Brainpool-P512.
The standard rationale for 256-bit symmetric ciphers is to protect against Grover's algorithm, which would halve the security level. Howe... |
If i add a password which has (X) bits of entropy as a tag to a picture which has (Y) bits of entropy, will the resulting image have an entropy equal to (X + Y) ?
How many bits of entropy i get if i save a password which has (A) bits of entropy inside an empty text file, then i use "copy /b" command to combine the text... |
I am reading Dan Boneh's book and I am stuck on Theorem 2.11, whose proof is left as an exercise.
The question is: prove that if $\lim_{n \rightarrow \infty} f(n)n^c = 0$ for all $c > 0$, then $f$ is negligible.
Here, negligible function is defined to be a function $f : \mathbb{Z}_{\geq 1} \rightarrow \mathbb{R}$ such ... |
I stumbled upon hummingbird-2 encryption algorithm when I was looking for a lightweight encryption module that can be used in resorce-restrained environments like Network-on-Chips.
A problem I faced when reading https://eprint.iacr.org/2011/126.pdf was that the paper does not mention any decryption procedure and only I... |
I need an encryption algorithm that doesn't require keys and computationally easy to encrypt, hard to decrypt.
Decrypting can involve brute force.
If the algorithm can be applied again and again (encrypt text, then encrypt the encrypted, ...), it would be better as I would be able to scale the time to decrypt as I will... |
I saw a table comparing Hash/Mac/Signatures in this post.
I was wondering if I can integrate digital certificates into it like this:
Hash
MAC
Signature
Certificate + Signature
Integrity
Yes
Yes
Yes
Yes
Authentication
No
Yes
Yes
Yes
Non-repudiation
No
No
Yes
Yes
Identification
No
No
No
Yes
Kind of keys
... |
I am developing a post quantum safe GPG like program, is argon2 quantum safe cryptographically for GPG like application.
|
is HMAC-SHA512 quantum safe , I am planning to use it for encrypt-then-mac scheme with aes256-cfb mode for a post quantum safe PGP like protocol.
|
Would something like this be a reasonable way to implement the double ratchet with libsodium? The sodium port that I'm using is quite limited and does not offer a kdf.
Here is a link to the libsodium documentation page regarding the scalar multiplication.
What crypto_scalarmult_base / crypto_scalarmult does is: "comput... |
I have a question for those that might be familiar with the ligero protocol: Ligero
In this protocol to be using an MPC in the head paradigm: described here. However, in the description of their zksnark they only use interleaved Reed-Solomon checking, but no MPC.
Why is that? Why do they talk about the MPC model they w... |
I have an encrypted password I must decrypt as part of a challenge. Along with the password came a few UNENCRYPTED RSA private keys
From what I understand, all I need in order to decrypt the password is the private key, which I have. However I don't understand what software I need to use in order to decrypt the passwor... |
The lightest, or fastest cipher, that is well known and quite secure like AES. Is ChaCha20 a good option? Are there any better alternatives that are faster but still as secure?
|
I generate two uniformly random 127-bit integers $a$ and $b$.
I calculate $c=a+b$, which means $c$ can always be represented as a 128-bit integer.
$c$ will not be uniformly randomly distributed, but I need to use it as entropy for a private key. I do not have the option of calculating $c=(a + b)\ mod\ 2^{127}$.
How can... |
I researched online and found AES-GCM and ChaCha20Poly1305 aren't post quantum secure. So I am planning to use symmetric AES256 cipher in CFB mode do I need to implement MAC using HMAC like HMAC-SHA512 if I use post quantum digital signatures?
In my program a post quantum key exchange will ensure exchange of shared sec... |
Could you explain with an example what does it mean to be Plaintext-awareness. I have read the wiki definition. It says that "A cryptosystem is plaintext-aware if it cannot genenerate a valid ciphertext without being aware of the corresponding plaintext".
As an example, consider the RSA cryptosystem without padding. In... |
I'm trying to do this cryptopals challenge for breaking ecdsa with biased nonce but everything I do fail to work. I'm trying my attack with 4 signatures and 128 bit bias.
N = 115792089237316195423570985008687907852837564279074904382605163141518161494337 #order of secp256k1 curve
pk = 16627923497236951427941159362308027... |
Lets say we are given BFV encryption of x, let this encryption is represented as E(x). In FHE, the client can decrypt and get the value of x but what if we dont want the client to learn x. This paper suggests that:
the servers samples random r and perform E(x)+r and send that to client
The client decrypts and get x+r
... |
I was wondering if I have to keep my data safe in an age when quantum computers become a reality. Which AES block cipher modes will be secure? Will AES-OCB will be quantum safe if used in a PGP like application?
|
Suppose a 256 bit hash is used (SHA2, SHA3, ...).
How does the Winternitz OTS perform at various signature sizes?
I'd want to compare to a generalized K-teeth Haircomb:
It's signature is $K$ of these 256-bit hashes
the public key is one hash.
We are signing a 256-bit message digest as well
the chain length is approxim... |
I know schemes like BFV, BGV, and CKKS supports SIMD operations where the plaintext is vector of values instead of polynomial. I am wondering if RGSW/TFHE kind of schemes can also support SIMD operations?
As explained in this paper RGSW can be defined as list of BFV cipher texts so I am thinking if it can also take adv... |
Lattice-based PQC KEM has small probability of decryption failure
In an offline setting it can be catastrophic despite being improbable.
Proposed mitigation:
let latice1 and latice2 be two separate instances of the same kyber scheme
lt1pk: lattice1 private key
lt2pk: lattice2 private key
generate entropy string SS
gene... |
I read online that AES-256 is Quantum Safe , so AES-256 used in AES-GCM and AES-OCB should be quantum safe , just wondering is ChaCha20Poly1305 quantum safe , if it is then is it better than AES-256 with GCM or OCB mode?
|
Previously, I used AES CBC 256 with 256 bit key and 128 bit IV.
However it seems slow so I decide to switch to AES GCM 256 bit key, 96 bit IV which has some parts I don't understand such as:
Auth tag: the output of AES GCM when encrypting and decrypting needs it
Can I prepend it to the encrypted cipher text so it's in... |
TL;DR
Does hashing a private key, then XOR[ing] the digest (twice recursively, with offset) on the secret have any glaring issues?
Is partial digest recognition possible?
Description
User provides a private key 16+ chars
User provides a secret < 128 chars (for now)
We compute a digest of sha512(privateKey)
Scramble di... |
if I use an one time pad key generated using a cryptographically secure random source like python's secret module , to encrypt a message, will the one time pad scheme be secure?
I think the entire security of one time pad scheme will depend on cryptographically secure random source, since such randomness is already use... |
Consider this question.
Say I would want to do something similar for $E_2:y^2=x^3−x+1$ over $\mathbb{F}_{3^m}$. How would I proceed?
|
What happens if you encrypt data with a good cypher that produces a cyphertext that looks random (say, AES but avoiding ECB mode), and then apply a Vigenere cypher to the encrypted random-looking data?
Encrypt data so it looks random (for example with AES-CBC)
Choose a long random binary key for Vigenere (for example:... |
Context: paper on pairing based cryptography, question 1, question 2.
Let $E: y^2 = x^3+x$ be an elliptic curve over $\mathbb{F}_{q}$ where $q=3^m$ for some $m\geq 1$.
Then I know that
$$
\# E(\mathbb{F}_{q}) = \left\{ \begin{array}{ll}q+1 - 2\sqrt{q} & m\equiv 0 \mod 4\\
q+1 &m\equiv \pm1 \mod 4\\
q+... |
I am trying to use argon2 hash to derive secret key to be used for AES-GCM , in package argon2-cffi in python there is a function argon2.low_level.hash_secret_raw(secret: bytes, salt: bytes, time_cost: int, memory_cost: int, parallelism: int, hash_len: int, type: argon2.low_level.Type, version: int = 19) → bytes¶ , I r... |
currently I am using parameters for argon2ID in terms of timecost , memorycost , parallelism higher than what is recommended in RFC9106 https://www.rfc-editor.org/rfc/rfc9106.html for increased security, the parameters i use are :-
Timecost=12
Memorycost=2097152
parallelism=4
will this result in increased security or r... |
The article Ligero++ (https://dl.acm.org/doi/pdf/10.1145/3372297.3417893) says "The number of constraints in R1CS maps to the number of multiplication gates in arithmetic circuits." But I understand the basic way to map an arithmetic circuit to R1CS will also map additions as constraints as shown in Vitalik Buterin's b... |
Here the encryption is done as follows :
$$C=P^e \textrm{mod} \, n =(P_1||P_2)^e \textrm{mod} \, n.$$
Here's my scenario that the adversary with CCA2 wins.
The adversary chooses $X_1, X_2$ of the same size with $P_1, P_2$ and multiplies $C'=(X_1||X_2)^e \textrm{mod} \, n$ by $C$ to get $CC'=(P_1X_1||P_2X_2)^e \textrm{... |
This is a well-known exercise that has already even been posted here.
I understand both arguments to prove and disprove that $F'$ and $\bar{F}$ are PRFs,
as I explain below,
however, it seems that the proof also applies to the case where $\bar{F}$ is not a PRF!
Assume $F$ is a PRF, then we have to prove that each of t... |
It is argued that the Vigenere cipher is easy to break using the Babbage's solution. But this solution counts on finding the repetetive occurences of letter groups(words if you will). What if my key is thousand letters long. Wouldn't it then be very unlikely that the same word gets ciphered with the same portion of the... |
I'm familiar with the concept of batching in the context of (Fully) Homomorphic Encryption - whereby many values can be encrypted as a single ciphertext and operated on simultaneously in an SIMD/vector-processing like manner.
Is it possible to utilise batching with any of the Partial Homomorphic Encryption schemes (suc... |
I recently got doubtful to the usefulness of psuedorandom generators(PRG) in cryptography.
Based on Kereckhoff's principle, we always assume that the used algorithms are made public.
So, when we use a PRG to generate a long key from a short key, we are broadcasting the PRG algorithm too.
When we use the output of a PRG... |
I am trying to check if some compressed public key corresponds to an elliptic curve equation (secp256r1). As far as I know it should be valid once the following equation is fulfill y^2 = x^3 + ax + b or y^2 % p = (x^3 +ax +b) % p. Supposing that I have the following key:
pubkey = 027d550bc2384fd76a47b8b0871165395e4e4d5... |
We are trying to generate some self-signed certificates to test our cybersecurity firmware before switching to a "real" CA-signed chain of trust. The specification we are coding to mandates that the keys are to use ED25519 and the certificates are to be signed with EDCSA-with-SHA256. We are working with OpenSSL 1.1.1q ... |
I read through RFC5869 and I didn't see any recommended or required octet length of the IKM used in the HKDF-Extract operation. Is there any relationship between the Hash method used in the HKDF-Expand operation and the IKM length? e.g. when using SHA-256 this requires the IKM to be a 256-bit key.
|
I'm building a project using libsodium's AEAD + Key Exchange system and want to write a proof justifying the security of the project. I am wondering if I can find a source detailing the exact security definition libsodium's Key Exchange system satisfies.
I know the textbook definition of IND-CCA2 and that AEAD satisfie... |
I want to use cryptographic function that returns the initial input or something related to it like its hash, the function should work like Encrypting some data or its hash, then encrypt the output of the data, and encrypt it again another time, and the loop continue to specific number of iterations and finally it can ... |
I am having a 32 byte shared secret from a KEM , I want to use AES-GCM for encrypting messages in this process random iv has to be created , can I use this iv as salt for hkdf-sha256 to generate more keys, will this be secure? I will create 2 keys one for AES-GCM and another for HMAC-256
|
I already have experience with quantum computing and the mathematics behind it. I also know the quantum cryptography side e.g. BB84, etc.
I now want to move on to post-quantum cryptography and am therefore looking for suitable sources. Favored here is primary literature in the form of books, however there doesn't seem ... |
I am wondering how secure it is to share digital signatures with a 3rd party (signed using one private key).
For example, let's say I'm signing a million different messages with my private key and send to a 3rd party. How likely is it that this 3rd party can reverse-engineer my private key simply because they have a mi... |
Suppose I know an RSA public key $(n,e)$ and I create two ciphertexts: An RSA ciphertext $C_1 = m^e \mod n$ and a Paillier ciphertext $C_2 = g^m \cdot r^n \mod n^2$.
Is there a known efficient method to prove in zero knowledge that the two plaintexts are equal $\mod n$?
|
since digest size of sha512 is 512 bits or 64 bytes , is it safe to use values lower than 64 bytes as input to hkdf?
I learned than hkdf uses hmac internally and input for hmac-512 is recommended to be equal to digest size that is 64 bytes.
|
It is known that Multiplicaiton Triple (MT) can be used for secure online multiplication, which is defined by $\mathsf{Mul}(x, y)=(z_0, z_1)$, where $x\cdot y = z_0 + z_1$
$P_0$ sample random $a$, and $P_1$ sample random $b$
By running the MT protocol, party $P_i$ gets $(a_i, b_i, c_i)$, where $i\in\{0,1\}$ and $(a_0 ... |
Hi newbie here is there any minimum length for salt and info passed to hkdf based key derivation or is using 32 byte randomly generated bits for salt and info can be used for all hkdf
|
I read from Is GCM mode of authenticated encryption quantum secure? that AES-GCM will be insecure if the attacker is allowed to perform entangled queries on your GCM implementation, and return entangled responses, then, no, GCM is known not to be secure against this model; the attacker can use Grover's algorithm on the... |
I'm trying to predict the next output of random numbers (bounded from 0 to 32) generated by the java.util.Random class. The code is shown below:
Random random = new Random();
int first = random.nextInt(32);
int second = random.nextInt(32);
int third = random.nextInt(32);
I know that Java's Random class uses a LCG with... |
I have 16 byte shared secret , I am using HKDF-SHA256 to derive 2 ,32 byte keys , one for encryption aes256-gcm and another hmac-256 , the salt info used for HKDF are sent publicly along with the encrypted message will it be a problem if an attacker tampers these values.
is there anyway to detect tampering.
|
Say a Human is operating their trusted computer, Alice, and Human wants to hand copy a collision resistant commitment, with a security factor of 128 from Bob on to paper. Naturally we want the commitment written by Human to be of least entropy possible to reduce the chance for human error and carpal tunnel syndrome.
To... |
It is well known that Grover's algorithm can solve AES in $O(\sqrt{n})$ time, which is why symmetric key length needs to be double to maintain their security level in the face of a quantum adversary. A recent eprint paper claims there exists a polylog time attack on AES (or searching unsorted sets in general) using a ... |
I am using a PQ-KEM to get a 32 byte shared secret. I want to derive 2 keys , 1 for encryption of message using AES-CTR and another for HMAC-512. can I safely ignore salt and info parameter in hkdf-sha512 as they are marked optional?
I want to skip salt parameter because in https://datatracker.ietf.org/doc/html/rfc5869... |
I fail to understand what block ciphers can do that stream ciphers cannot.
Also aren't they construct able from one another.
prg(stream cipher) -> prf -> prp(block cipher)
Any practical example would be very helpful
|
Suppose having an arbitrary $GF(2^n)$ element $x$. Its distribution is unknown.
The task is to derive two $GF(2^n)$ elements $y$ and $z$, that have uniform distribution and are independent from each other.
Let $x$ be known to a possible adversary.
The obvious solutions are:
Use some KDF, but it takes a lot of time to ... |
Suppose I have $k$ blocks $B_i$ each consisting of $n$ bits. For erasure code purposes I'd like to be able to produce a computationally binding deterministic hash/fingerprint/digest $H$ such that $\mathrm{verify(x, H)}$ succeeds if $x$ is an additive combination of arbitrary $B_i$ (in $GF(2^n)$), and if not it succeeds... |
My computer generates a 65536-bit RSA keypair in 106 minutes. Is there a way to generate them faster by some trade-off? Can they be created in bulk, so long as they're able to encrypt and decrypt? Is it possible to generate large RSA keys quickly, for example by allowing the keys to be weak?
Are RSA keypairs proof of w... |
With regard to LPN over non-binary fields like $\mathbb{F}_3,\mathbb{F}_5,\cdots$, are there any studies about that ? We also would like to know any articles that have a formal definition of the non-binary LPN.
We know large amount of the binary LPN studies, but why is the non-binary LPN rarely studied ?
We referred to... |
I recently read a StackOverflow post about a CS(P)RNG generating sixteen bytes of random data. The OP wanted this data to be random and unique. One of the answers said that uniqueness and randomness are mutually exclusive when talking about a CS(P)RNG. I commented on that matter with the following example:
The list [1... |
I'm a bit confused by the standards and some replies regarding zero (the point at infinity) in elliptic curves ElGamal.
TL;DR: Why do some people recommend excluding zero? It has nothing to do with key leakage due to insufficient order as those attacks are preventable by group membership checks (i.e. not related to zer... |
The motivation for key aggregation multisig and threshold schemes (e.g. MuSig(2), FROST etc) in Bitcoin is obvious. Signatures are a large part of every transaction, all the nodes on the network are attempting to verify every signature and signatures in many cases have to be stored as part of the blockchain data struct... |
I read: What are the differences between a digital signature, a MAC and a hash?
and Found this amazing answer: https://crypto.stackexchange.com/a/5647
But one question remains:
I know that for huge input Hash's Output is much smaller, SIG's Output is of same size, but what about MAC's Output?
If MAC's Output is of same... |
I'm trying to digest the "new hope" paper on post-quanum key exchange and understanding parts of Ring Learning with Errors, despite using every online resource I can find (including the references of 1). I'm sure regular Learning with Errors made some sense to me.
So let's start by with sampling. If you define a polyno... |
In the accepted answer to a question in Computer Science Stack Exchange, it was mentioned that a block cipher in counter mode makes a random number generator with a large bitspace, which visits every element of the domain exactly once before cycling.
Of course, with usual block cipher block sizes (of 128 bits and more)... |
I already asked a question about the feasibility of LWE when the matrix A is sparse or small here.
Let $q$ be a prime, let $\chi$ be a distribution of $\textit{small}$
elements over $\mathbb{Z}/q$, and let $n,m$ be two integers
(dimensions of vectors that we work with). Sample $s \leftarrow \chi^n$, $e \leftarrow \chi... |
I was looking into the opaque authentication protocol and they discuss an oracle, which, if I understand it correctly is a projection $Z$ from $f$ to $g$ ($g$ at least the size of $f$), which maps inputs from $f$ to $g$.
If $f$ and $g$ are the same, is this not comparable to an encryption with a substitution cipher of ... |
I have been doing some research into recursive SNARKs. But I haven't found a working code example such as this one using Zokrates or this one using snarkjs. Anyone knows one such example, say, for proving a hash chain?
Recursive STARK example is also fine.
|
I'm going through the datasheet for MifareDesfire ICs. Throughout the document, there are mentions of "key version". For example, section 9.3 of the document states:
Hardware AES using 128-bit keys featuring key version, data authenticity by 8 byte
CMAC
I'm unclear on what "key version" refers to within this context... |
The famous result of Goldreich, Goldwasser, and Micali (GGM) constructs a PRF $F$ from a PRG $G$:
F(k,x):
v := k
for i = 1 to length(x):
if x[i] == 0 then v := left half of G(v)
if x[i] == 1 then v := right half of G(v)
return v
($G$ is a PRG with outputs twice as long as inputs)
This PRF cal... |
Are there any ciphers that are
provably secure (reducable to a hard problem (including like factorization, not necessarily to NP-Complete or harder) )
are practical (not necessarily for too much bulk action like videos, but for small text messages, by humans) with decent security ~ 2^100
notes:
blum-blum shub seems... |
Suppose we are trying to construct a cryptographic scheme, say public key encryption, and I can prove the IND-CPA security of the PKE scheme when any adversaries perform at least $T$ queries. That is, our proof only holds when the number of ciphertexts allowed by an adversary is bigger than at least $T$.
In other words... |
i am new to cryptography , i am using article https://medium.com/asecuritysite-when-bob-met-alice/hmac-and-hkdf-df4e194752d1 for reference , while using salt with hkdf to derive multiple keys from a single key for encrypt then mac scheme is it safe if i hard code the random salt value within my program .
i will use pa... |
I am trying to find a way to mine bitcoin faster than an ASIC by using a CNF representation of sha(sha(hash)), which would be an equation containing a few hundred thousand clauses, let's call it n clauses. If I brute-force guess and check solutions, what is the fastest way to check if a given solution satisfies the equ... |
I have doubt like when in the IPsec we use a DH group for key exchange. It takes a prime number and $g$ value from group bit.
How does the key exchange payload and nonce help to generate the shared secret in the he message 3 & 4 exchange?
|
Practical implementations of digital signature algorithms (DSAs) employ hash functions to ensure that input is small and of a fixed sized; otherwise, DSAs would be too slow for most real-world applications. Given that hash functions map arbitrarily long inputs to (smaller) fixed sized outputs, you may have several inpu... |
I know I am not supposed to ask for answers, which I am not. I have the solution but I don't understand how 'e' is selected, pls see my explanation below.
I am doing practice questions for my Cyber Security Paper.
One of the question I came across is:
"Using RSA Technology, Alice wants to send Bob the number 10. Alice ... |
In the paper about ABE (like this), the access structure is defined as follow:
Let ${P_1,P_2,...,P_n}$ be a set of parties. A collection $A⊆2^{\{P_1,P_2,...,P_n\}}$ is monotone if $∀B,C$: if $B∈A$ and $B⊆C$ then $C∈A$ ...
What is the meaning of this notation: $2^{\{P_1,P_2,...,P_n\}}$? Can you give some example while... |
I designed a simple library (golang) for use as session token for web applications. The idea is simple:
the token will be 16-byte long, denote it as t
generate a random byte m, put it into t[0]
encode the expiration timestamp as a big endian uint64, append the lower 48-bit of it into t.
append the big endian represen... |
Consider secure two-party computation against malicious adversaries in the standalone model.
I know that the "rewinding" technique can be used to extract the corrupt party's input, e.g., in $\Sigma$-protocol or interactive commitment.
I am curious about whether this technique can be generally applied to secure computat... |
Let $\mathbb{F}_q$ be a large finite field. What if I invent how to efficiently construct pairs of elliptic "cryptographically strong" $\mathbb{F}_q$-curves $E_1$, $E_2$ isogenous over $\mathbb{F}_q$, that is $\#E_1(\mathbb{F}_q) = \#E_2(\mathbb{F}_q)$, in such a way that nobody (including me) knows an $\mathbb{F}_q$-i... |
Given an hash H that is not collision resistant, for example 80-bit digest, if we use the following double hashing scheme: H(SHA2-256(x)).
Does this scheme increase the collision resistance?
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