instruction stringlengths 32 27.2k |
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In Boneh et. al.'s ABE scheme (https://eprint.iacr.org/2013/669.pdf, https://link.springer.com/content/pdf/10.1007/978-3-642-55220-5_30.pdf), the result value for the arithmetic function is selected and fixed to zero. In other words, if the arithmetic function is defined as $f(\mathbf{x})$, the user can decrypt if and ... |
Nested attributes were introduced for the first time in the paper with the title "SmartABAC: Enabling Constrained IoT Devices to Make Complex Policy-Based Access Control Decisions".
What is the difference between nested attributes, multiple attributes, and hierarchy attributes?
In this paper, the authors make 6 policy ... |
I can’t figure out why the static public key of the initiator/recipient cannot be sent as plain text in the Noise KK pattern and what kind of cryptographic vulnerability does it provide?
For example, in the pattern Noise XX, the recipient's static public key is sent encrypted, although it can be easily obtained by man-... |
If a user cannot generate a proof locally for a large circuit in SNARK in his phone or browser, he can delegate it to a server. However, he has to tell the witness to the server(s), which violates the zero-knowledge property of SNARK. What is the state of the art for delegating proof generation without disclosing the w... |
Would it be over-engineering to for example hash the random numbers a random amount of times too, for instance when using the CSPRNG in client-side JavaScript? (assuming this is not the strongest CSPRNG)
Edit: Or would it instead be wise/necessary to rely on more devices of randomness (like mixing/hashing a Client Secu... |
In a sigma protocol, a well known transformation to a signature is Fiat-Shamir, where message derived randomness is mixed into the randomness of the challenge. A natural example is Schnorr signatures. This is also called a Signature of Knowledge.
Suppose you start with a modern, transparent ZK-SNARK to prove knowledge ... |
How is the seed of PRNGs generated? They can't be hardcoded I am guessing.
|
In this paper Alzette "ARX-box" is presented and on page 9 authors claim about XORing round constants:
They also break additive patterns that could arise on the left branch due to the chain of modular addition it would have without said constant additions.
Round constant is "c":
x ← x + (y ≫ 31)
y ← y ⊕ (x ≫ 24)
x ← ... |
I know this is theoretically bad practice, but please bear with me…
Assuming following spec:
Salt and IV are randomly generated using cryptographically-secure RNG.
Argon2 is used as KDF so key_1=Argon2(shared_salt, passphrase_1) and key_2=Argon2(shared_salt, passphrase_2).
Both passphrases are not vulnerable to dict... |
In RFC 7748, it is explained how the Montgomery curve, curve448, is deterministically generated from the prime $p = 2^{448} - 2^{224} - 1$. It is also explained how the generator (given below) for curve448 is derived.
U(P) 5
V(P) 355293926785568175264127502063783334808976399387714271831880898
4351... |
Suppose I have a webpage that publishes some number x that changes over time and the page is publicly accessible.
I would like to somehow create a proof that this webpage published value y at time t. Is there a way to make this possible?
This needs to be done without any sort of central authority, so it's not good enou... |
For non-deterministic ECDSA:
Given message $m$ and private key $p$, produce a series of signatures $s_i = signature(p,m)$, $i=[1,n]$.
Does there exist some function $f$ such that $j_i=f(s_i)$ and $j_1=j_2=...=j_n$ ?
|
I am trying to find $d$ given $e$ and $\varphi(n)$. I found a solution online but I don't really understand why it works.
sage: bezout = xgcd(e, phi); bezout
(1, 4460824882019967172592779313, -1667095708515377925087033035)
sage: d = Integer(mod(bezout[1], phi)) ; d
4460824882019967172592779313
sage: mod(d * e, phi)
... |
For semi honest MPC protocols, adding some errors can easily make the output wrong.
I wonder beyond that, can malicious adversaries make some attacks against semi-honest protocols to obtain private inputs or some other private data? And if they can, how to do that?
I wish to get some answers or literature about this qu... |
Consider a family of pseudorandom functions $F$, each member $f_k$ of this family is indexed by a key $k$. It is true, due to a result by Barak et al, that black box obfuscation is not possible for a generic family of this type.
However, is it possible to apply something like indistinguishability obfuscation ($\mathsf{... |
I've encountered the following question while practising for an upcoming exam in Cryptography and would like to know if I'm on the right track:
The following is a suggestion for a DES-based commitment scheme:
To commit to $0$, choose a random $k$ and return
$DES_k\big(\overline{0}\big)$ where $\overline{0}$ is a 64-bi... |
Are there any clever (fast) methods for adding the basepoint (generator) to an arbitrary point on elliptic curve, finally ending in affine coordinates?
I.e. if G is the generator for a group on the curve (e.g. 25519) and P is an arbitrary point, is there a faster-than-naive way to find P + G in affine coordinates?
I'm ... |
I am trying to implement a random number generator (which should be cryptographically secure), I am thinking of combining multiple LFSRs, is it a good choice?
I've also heard I can create RNGs from hashing algos like shake256, How is that done?
|
EDIT: At a high level I am trying to create a scheme where Alice can prove to Bob that some external site has a certain piece of data (say her Bank account has balance > X) . She does not want to give Bob access to her account, but wants to prove that her bank website returns a certain result without showing it... basi... |
Every API that I have ever signed up with gives you a secret key that you can then paste into your application. They know the key, and so do you. (The one exception may be VAPID for Web Push).
Why is this the case? Some apps and protocols already give users a public/private key pair, and store only the public keys in t... |
I need to use Azure Key Vault HSM to sign arbitrary data in a PKCS#7 CMS. There are plenty of libraries and packages that can do this if you supply them with the private key, but obviously I don't want to export the private key from the HSM, so I've built my own PKCS#7 object in C# using Asnwriter.
I'm using the ITU-T ... |
I have an application that erasure codes data in chunks. Lets say there are 3 data chunks and 2 parity chunks (it could also be 6-3, 10-4 etc). Each chunk is 1MB of data and has a CRC32 checksum associated with it.
D1-CRC1 D2-CRC2 D3-CRC3 P1-CRC4 P2-CRC5
To recover lost data, I need any 3 of the above chunks to recove... |
Is there any software that can output all possible solutions to a substitution cipher?
I have a 34 character substitution cipher as follows:
ABHIJCKDELMFNOEPQ
RDSTUVWGFADBXCYGZ
15 of the characters in the cipher are repeated.
I would like a software to output all possible word combinations that will fit the cipher (Eng... |
A hybrid scheme is a combination of a classical and a post-quantum scheme. In the hybrid model, if even the post-quantum section is broken, the hybrid scheme is still secure against non-quantum attacks. But, as far as we know, NSA doesn't like hybrid schemes, for example NSA didn't consider hybrids in her new updated C... |
I am looking for some algorithm or implementation on Pailler cryptosystem-based verifiable shuffles for mixNet. So far, all the verifiable shuffles and mixNet are available for ElGamal cryptosystems like the Groth method, etc. Does anyone know the implementation done specifically for Paillier encryption? If not, can I ... |
I am building a chat application where I want to encrypt each character while they are typing. I would require a stream cipher for that.
I am planning to use AES-CBC mode with HMAC. Are there any security risks if I use AES-CBC mode to encrypt `0's to generate blocks of the one-time pad and then use that one-time pad s... |
Suppose we have a 32-bit message $ M=(m_1,..m_{32}) \in \{0, 1\}^{32} $ and we have secrets $ F_{i, b} $ and $ G_{i, b} $ (2x32+2x32=128 secrets in total).
$$ \forall 1 \leq i \leq 32, b \in \{0, 1\} : F_{i, b}, G_{i, b} \in Z_q $$
And now we define two functions $ f $ and $ g $ respectively:
$$ f(m_1, .., m_{32})= \su... |
I'm trying to come up with a Zero-Knowledge proof for the following setup.
Using RSA encryption, Peggy chooses a random $M \in \mathbb{Z}^*_n$, computes
$C=M^e \mod n$ and sends $C$ to Victor. Peggy wants to prove that she
knows $M$.
I've constructed the following protocol, but am unable to justify soundness - which ... |
Good day.
How I can modify elliptic curve point, like number modulo ?
number example, with unknown privkey 5555555555 :
5555555555 % 2500 = 555
how to get pubkey with privkey 555, from pubkey with privkey 5555555555 using any math operation or code incude change modulo of curve, calculatex and y coordinates modulo 555... |
Ed25519 uses a composite order Elliptic Curve but works in the prime order subgroup of the main group. As per group theory, the subgroups use the group operation.
However, as per this, Ed25519 implementations don't do this.
But every existing implementation implements scalar arithmetic $\bmod q$, the order of the prim... |
I am designing my first web3 app and I would like to use MetaMask as an identity and crypto provider. My web3 app will encrypt user data with AES-GCM, but I do not want to generate and store an encryption key (as well as iv/salt) anywhere on user device. Instead, I would like to use MetaMask connection and the private ... |
Below is a suggestion for a zero knowledge proof for the existence of both a $k$-independent set (IS) AND a $k$-vertex cover (VC). It was given as an example of an interactive proof that is not computational zero-knowledge due to leakage of information, and I'm having trouble understanding why.
Peggy selects a random ... |
Imagine you have RSA key pair. You also have some text data. So public key and text data are visible to everyone. Question is, if you sign the text_data with the private key, is the result considered as good secret? For example is it good idea to convert it to base64 string and use it as a password?
Real world problem ... |
Some applications may require quick transition to post-quantum signatures, and stateful hash-based signatures fill that role (cf. CNSA 2.0).
My question is (ignoring statefullness, focusing on space/time efficiency), how do these schemes (e.g. LMS/XMSS) compare to whatever is used now (RSA, DSA, ECDSA)?
|
I've seen some mentions of a "SHA-256/192" online. Clearly, this means the output of SHA-256 is truncated to 192 bits, but does it also use different Initial Values like SHA-512/256?
|
Ed25519 uses a composite order Elliptic Curve but works in the prime order subgroup of the main group. The signing operation should be using a generator/Base Point from the prime order subgroup.
This blog seems to say the following - Honest Ed25519 signers only work in the prime-order subgroup (i.e they chose a generat... |
Ed25519 uses a composite order Elliptic Curve (with a cofactor $8$) The algorithm however in the prime order subgroup of the main group. The signing operation should be using a generator/Base Point from the prime order subgroup.
There are the parameters
Order of the curve is $8.q$ where $q$ is a large prime.
$a$ = scal... |
is the complete NTT is the fastest algorithm to multiply polynomials or there are hybrid versions that are faster than complete NTT multiplication?
|
RFC 5869 Defines HKDF-Extract in section 2.2 as:
HKDF-Extract(salt, IKM) -> PRK
TLS 1.3 RFC 8446 defines the first part of the Key Schedule like this:
0
|
v
PSK -> HKDF-Extract = Early Secret
|
... <<< omitting unrelated lines >>> ...
v
Derive-Secret(.... |
To prevent second pre-image attacks, the Merkle Tree implementations I've looked
at add a 0 prefix to the leaves and a 1 prefix to all other nodes as described
at the bottom of this link:
https://flawed.net.nz/2018/02/21/attacking-merkle-trees-with-a-second-preimage-attack/
If we assume the Merkle Tree is a Complete Bi... |
Let's say you generate an SSH RSA key pair with ssh-keygen -t rsa -b 2048. You'll end up with a public and private key.
id_rsa
id_rsa.pub
ssh-keygen will prompt: Enter passphrase (empty for no passphrase):
My understanding is that id_rsa will get one prime and id_rsa.pub will get another prime. What purpose does the ... |
I'm trying to solve the following question:
The following is an interactive proof for knowledge of the factorization of $n=pq$ ($p,q$ are two large primes), where $P$ doesn't wish to reveal the factorization itself ($p,q$). Determine whether it is a ZK proof. If it is, prove whether it is
perfect zero-knowledge or com... |
I'm given three values $s_0,s_1,s_2 \in \mathbb{Z}_m$ that follows the recursion formular $s_{n+1} = as_n+b \mod m$.
I know $m$ and want to calculate $a,b$. It's easy to see that $a=\frac{s_1-s_2}{s_0-s_1}$ however in my case $gcd(s_0-s_1,m)\neq 1$ thus I'm unable calculate the multiplicative inverse of $s_0-s_1 \mod m... |
How can I check if the random number generator library that I am using for my app is cryptographically secure or not?
|
In the process of finding RSA key pairs, we first find a e that is relatively prime to φ(n) (where n = p × q), and then find d such that e × d mod φ(n) = 1. Is d also relatively prime to φ(n), or not necessarily?
In practice, e is usually chosen to be 3 or 65537, but if we choose e to be a large enough number, can e an... |
Let $F(x_1,…,x_n)\mapsto(y_1,…,y_n)$ be some arbitrary computable function.
Suppose there are $n$ parties, where each party $i$ encrypt its message $m_i$ with a public key $\mathrm{pk}_i$ and obtain $c_i$. Is it possible for parties to execute a secure multi party computation $A$ with the same functionality as $F$, suc... |
Client-Server Example
apps/openssl req -x509 -new -newkey ec:<(apps/openssl ecparam -name secp384r1) -keyout ecdsa_CA.key -out ecdsa_CA.crt -nodes -subj "/CN=oqstest" -days 365 -config apps/openssl.cnf
apps/openssl req -new -newkey falcon512 -keyout falcon512_srv.key -out falcon512_srv.csr -nodes -subj "/CN=oqstest ser... |
Is there any educated views or references on how the PQC NIST finalists compare to legacy crypto with regards to power consumption?
Many thanks
|
I am searching literature on a more general notion of pseudorandom function where the range of the function is not the entire set of all binary strings of a given length, but rather a specified range dependent on the security parameter. Something like this, which I wrote up:
It seems that in some use cases, such a def... |
I'm aware of the many questions on this topic, but I'm still not sure what went wrong with my reasoning here below.
I'm assuming use of AES with key size $2^{256}$ and messages of size $2^{128}$, using ECB.
When I tried computing the expected number of plaintext-ciphertext pairs required until key-identification, I rea... |
I'm thinking of the problem of a distributed tinder: a network of peers, who want to match with each other confidentially.
The solution I'm thinking about is something along the lines of Alice sending some message encrypted with Bob's public key that implies she likes him. She will not send this message to Bob obvious... |
In this post, there's a discussion on single DES not having a key that yields the identity function. It mentions at the top:
That proposition is false for 2DES (EE), even restricted to one key, because twice applying encryption with the all-zero key (and the Final Swap built into the Final Permutation) yields identity... |
In this survey, I don't understand the necessary of coefficient (paragraph 4.1.2) growth and the choice of $X^d\pm 1 $ or $ X^d \pm X^{d/2} +1 $, since later introduces $q$ which doesn't mention the coefficient growth. I want to understand this paragraph please and its importance.
Thanks in advance
|
I am trying to make a e-voting system based on blockchain and I am trying to think about a way that i can verify that a vote is legal without reavling the identity of the voter.
One of the solutions we thougth about was to use linkable ring signatures, but the problem with this aproch is that the more keys we generate ... |
Say one encrypts multiple plain text blocks with same IV but different keys using AES-256-CBC, can one infer concatenated ciphertext block boundaries through digital forensics?
Example
Plain text block 1: foo
Plain text block 2: bar
Ciphertext block 1: <Buffer 88 65 7f 9f 7b 9d 47 51 21 cc 22 c0 2a 9e 69 57>
Ciphertext... |
The overall DP under the strong composition theorem for k-mechanisms is ($\epsilon \sqrt{k log(1/\delta)}$, k$\delta$) such that each individual mechanism has ($\epsilon, \delta$)-DP.
But what if say, 25% of the total k-mechanisms have $(\epsilon_1, \delta_1)$-DP, while the remaining 75% mechanisms have $(\epsilon_2, \... |
Paolo, in Algebra: chapter 0, defines a left-$R$-module as a ring, $R$, an abelian group, $M$, and a map $(R \times M \rightarrow M)$ such that:
$r(m+n) = rm+rn$
$(r+s)m = rm+sm$
$(rs)m = r(sm)$
$1m = m$
where $m,n\in M$ and $r,s\in R$
In the definition of RSA in Katz/Lindell's Intro to Modern Crypto, key generation re... |
Not sure about this question. Have thought about it, but not entirely sure whether the structure HAS to be reversible or not.
|
For https://asecuritysite.com/public/lwe_ring.pdf#page=9 , could anyone explain how the encryption and decryption for LWE work ?
When I do more reading on https://summerschool-croatia.cs.ru.nl/2015/Lattice-based%20crypto.pdf#page=29 , someone told me that when decrypting we get $q/2 M + r e$. If we can bound $r e$ by $... |
Due to a comment stating "... QR-PKE is secure (CPA)..." I've been thinking of how to prove that it's not CCA secure, and would like to understand whether my proof is correct.
Here's the QR-PKE scheme:
$KeyGen(1^n)$ produces:
$sk = (p,q)$ - two large n-bit primes
$pk = (n, x)$ where $N=pq$ and $x$ is a random $QNR \in... |
I'm trying to use HKDF-Expand to derive lots of keying material (> 64GB) from a pseudo-random 512 bit key.
Now according to the HKDF RFC, the maximum amount of keying material you can derive in a single call to HKDF-Expand is 255 * HashLength, which in my case would be 255 * 64 = 16,320 bytes of output (Since I'm usin... |
The question is somewhat complex and directed to clearing things out.
Suppose that $n$ is the order of the cyclic group. It $n - 1$ is the number of all private keys possible
n = 0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141
We also know that every private and public key has its modular inverse. T... |
I've learnt in the university course that using BLS, one can generate an aggregate signature using public keys of a given parties. We can then use a given party's public key to verify his participation in the aggregated signature.
But... does BLS or any other scheme allow us to encrypt a message with the aggregated sig... |
Suppose there are $n$ parties with public keys $pk_1,...,pk_n$.
Is it possible that a server S constructs an algorithm $A$ so that for some public random nonce $r$ given as input, S computes some "oblivious function" whose output is a tuple of several cipher texts of messages, without knowing the messages?
Namely S com... |
In MPC schemes like ABY or MOTION, the modulo operation is based on a ring $Z_{2^l}$. So for arithmetic sharing, it is relatively easy to make addition operation in the ring.
My question is, what if I want to do addition in a modulo different from $Z_{2^l}$. Say I want to compute $a+b\ mod\ p$, should I find a corresp... |
My understanding of zk SNARK is as follows: through (flattening -> R1CS -> QAP), bind the answer of the original proposition to the solution vector s of QAP, and then because QAP is an NP problem. So if the verification is passed, the verifier can be sure that the prover knows s.
And because of the NP problem, the only... |
I have what I believe to be a Vigenere or similar polyalphabetic cipher (IC = 0.0459). However, the ciphertext is further encoded by 'Latin-like' letters, meaning I don't have the ciphertext alphabet (but have some idea of the plaintext translations. For example, the words for 'Water' and 'Ice' (using Japanese 'Mizu' a... |
Are there any available formulas to determine a $Y$ coordinate given only an $X$ for the Ed25519 curve? The closest thing I've come to find is the recover_x(y, sign) function in the EdDSA RFC at https://www.rfc-editor.org/rfc/rfc8032.html#section-6
Edit:
Using @kelalaka 's steps, I implemented this python code, but it... |
I encountered notes stating that, for certain fixed $A$, such as $A \in M_{n\log(q)\times n}$ as follows:
\begin{bmatrix}
1 & 0 & 0 &\dots\\
2 & 0 & 0 &\dots\\
4 & 0 & 0 &\dots\\
&\dots\\
2^{\log(q)-1} & 0 & 0 &\dots \\
0 & 1 & 0 &\dots\\
0 & 2 & 0 &\dots\\
0 & 4 & 0 &\dots\\
&\dots\\
0 & 2^{\log(q)-1} & 0 &\dots\\
&\d... |
I've been thinking about ways to take advantage of multiple asymmetric encryption schemes so that each key could be a backup to the others in case of cryptanalysis of one given scheme.
Those public key schemes could each secure one share of a symmetric key splitting scheme (as answered in Is there a multiple asymmetric... |
I am trying to understand point addition in RFC8032 section 5.1.4, which references the paper "Twisted Edwards Curves Revisited" (https://eprint.iacr.org/2008/522.pdf) to describe the quick way they perform twisted Edwards curve addition with fewer inversions.
I am reading through the paper and it makes sense until I ... |
What kind of tests can be performed on a public key to check if it is likely a valid key? The tests should be relatively fast - i.e. not computationally intensive - and not include modular exponentiation.
I'm asking this question as developers generally work (or should work) on the principle of fail fast, in which an e... |
I read this paper on RSA cryptographic accumulators have some questions on a few points :
"Universal Accumulators with Efficient Nonmembership Proofs"
https://www.cs.purdue.edu/homes/ninghui/papers/accumulator_acns07.pdf
I noticed this from the paper :
"Note that computing witness using auxiliary information may not a... |
I want to debug bcrypt rounds with a static salt using this python lib
import bcrypt
salt = bcrypt.gensalt(14)
password = b"foo"
foo_1_round = bcrypt.kdf(password, salt, desired_key_bytes=10, rounds=1)
foo_2_rounds_manually = bcrypt.kdf(foo_1_round, salt, desired_key_bytes=10, rounds=1)
foo_2_rounds = bcrypt.kdf(passw... |
:-) Hello
I was wondering if the signature hash algorithm was a part of the private key or just the signing process?
Should a signature instance depend on the private key? (Of course, still talking about ECDSA)
If I don't sha256 my data before calling a signature instance SHA256withECDSA. Does this have the same eff... |
From a text on Interactive Proofs
$x \in {0,1}^n$ is input
$V$ is verifier
$P$ is prover
$r$ is $V$'s internal randomness
$P$ provides a value $y$ which is claimed to be equal to $f(x)$
(Completeness) For every $x \in {0,1}^n$
$Pr[out(V, x, r, P) = 1] \ge 1 - \delta_c$
(Soundness) For every $x \in {0,1}^n$ and every... |
I'm reading Matthew Green's blog post on ZK Interactive Proofs
I don't understand the part where he explains how using a time machine shows that the prover is leaking zero information
Specifically, assume that I (the Verifier) have some strategy that
‘extracts’ useful information about Google’s coloring after observin... |
Currently I'm working on an intercepting proxy server for mosh connections.
I'm able to intercept the ssh session to get the shared secret and alter the connection information for the mosh client. The mosh client is able to connect with my udp proxy server which is started for the requested mosh session and redirects t... |
i am currently searching for a post-quantum, asymmetric encryption since I need to keep a few files safe for the next decades.
AES 256 is what I am using currently, but I would like to leverage the additional safety of a asymmetric encryption (like encrypting something on a server I don't trust to 100% / storing the pr... |
I read about bactracking resistance:
http://cs.yale.edu/publications/techreports/tr1466.pdf
https://arxiv.org/pdf/1810.02227.pdf
https://www.schneier.com/wp-content/uploads/2017/10/paper-prngs.pdf
Story (Motivational Story) in first paper is interesting. But seems to be theoretical.
Backtracking resistance is critical... |
I am currently reading a book called Serious Cryptography written by Aumasson to learn about Security. There was a paragraph talking about the security goal named indistinguishability (attached below), which reads in the section "Security Goals":
I've informally defined the goal of security as "nothing can be
learned ... |
Let's consider PRNG which is updating its state by using some cryptographically secure hash function. So it takes some input, returns output and this output is a new input. And so on.
Of course there is a risk that such PRNG would fall into short cycle. But it can be resolved by combining the state with counter or Weyl... |
Has there been any use of cryptographic function as a kernel function with support vector machine? There are several standard kernels to be used with SVMs each with its own scenario.
I was not able to find any kernel function which is a cryptographic, one-way, or trapdoor function other than this example of using discr... |
My mathematical assumption is $(g^rx')^x = g^r$ where $x'$ is the multiplicative inverse of $x$ and $g$ is the generator of the group. I am calculating $(g^rx')^x$ in ModularArithmetic group G using Crypto++.
CryptoPP::Integer a, b, c, r(rng, 1, p);
a = G.Exponentiate(g, r);
b = G.Exponentiate(G.Exponentiate(g, G.Multi... |
Update: The question below was asked before I realized that this is being done to prevent a side channel attack: https://github.com/advisories/GHSA-5p8v-2xvp-pwmc
What I am still curious about, is the math behind why this solution still works to decrypt Elgamal ciphertext.
Original Question:
libgcrypt elgamal decryptio... |
Is it possible to commit to a value $s$ and then prove in NIZK way that $g = q^s$ ?
Both $g,q$ are known. Thank you.
|
I'd like to create a public/private RSA key pair where the OID of both keys is rsassaPss. I can create the private key fine but when I extract the public key I expected the OID to remain rsassaPss but it actually gets converted to rsaEncryption.
This SO post Why does OpenSSL differentiate between PSS and non-PSS for pr... |
What is IV predictable in the CBC mode?
We only need one IV once for CBC mode, does the IV-predictable means we know the initialization vector before we start a CBC mode? Or it means we know each string which is used to XOR with the plaintext, such as the first IV, c_i(the ith ciphertext)?
|
I'm a bit of a layman here and would be after a Python-based solution to this.
I would want a python-based application approach that is capable of generating data (e.g. csv file) that is locked immediately upon writing it, and it is not possible for the user to decrypt its contents on that end but rather a proxy indivi... |
I'm working with the dieharder package to test a PRNG, but I don't quite understand the ntup parameter.
I get that the ntuple should be a set of consecutive bits. But why is the ntup parameter for most tests set to 0? Is it because these tests don't need ntup to operate? What would exactly change if one would change th... |
I am currently studying zero knowledge proofs. (specifically A short tutorial of zero knowledge -- Oded Goldreich)
In the interactive proof system Definition it is required that the prover has unbounded computation capabilities (i.e. executes a computationally unbounded strategy) while the verifier has somehow bounded ... |
I need to cipher and decipher text with randomly access. For this I decided to use AES in CTR mode which is a good compromise between CBC and GCM.
But CTR mode is malleable. It is not a big problem because texts that I will cipher have not predefine patterns and I don’t need authentication, I just want to avoid the abi... |
What requirements KDF and randomness extractor does not have to meet, but the the hash function have to meet? I suspect that using hash functions as KDFs and randomness extractors is enough, but in some aspects more than we need.
If we consider some weak, biased source of entropy it looks like randomness extractor:
do... |
I'm developing a device where I need to store a symmetric key that the customer uploads to the device.
The device is offline at all times, so centralized storage in HSM is not an option.
The device does not have a key-pad.
The key is used for data encryption/decryption when the device is active.
The key cannot be store... |
In MPC, AND and XOR gates are two mostly used gates. However, most of the solutions (Garbled Circuit or Boolean Secret Sharing) considered these gates having 2 input wires and 1 output wire.
I am curious on how the case of multiple input wires can be handled. Specially, suppose there are 3 parties and they want to comp... |
Modern hash function have to be at least 256-bit, due to birthday attack. But let's consider 128-bit hash function which takes as an input:
plaintext $\oplus$ salt
Salt may be know to attacker. Do such a functions would be secure if it has no other flaws?
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After reading this topic:
How do I construct a 256-bit hash function from 128-bit AES?
It looks like it can be done. If we have 128-bit into 128-bit secure mapping, indistinguishable from random (but vulnerable for birthday attack itself, because of its size), can we construct secure 256-bit hash function (especially i... |
From my limited research into this topic, it seems that AES can be brute-forced. One-time pad, on the other hand, cannot. Why then is it better to use AES than it is to use one-time pad? The only answer I have come to is performance, but this doesn't seem quite right.
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Are the digital signatures used in cryptocurrencies such as Bitcoin a type of zero-knowledge proof?
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I am trying to develop a Rest API using Kotlin/Spring Boot. The JSON request in it, should have a hashed password that was done using Argon2id. Getting the password hashed was pretty straight forward and simple enough! But I am stumped at how to verify what I receive in the JSON request is correct or not. That is match... |
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