instruction stringlengths 15 30k |
|---|
I'll answer the first question after the other questions as it depends on the answers given.
> *Which one should I choose? and for password-based key derivation 5 seconds delay using Argon2id with 6 iterations, 1 GB memory, 4 parallelism.*
That doesn't feel well-balanced to me. The memory requirement is mainly to... |
It's that time of the year - I'm trying to learn how AES-128-CBC encryption works. My key is (since it's AES-128) is 16 bytes, my IV is 16 bytes as well. My implementation of key wrapping does apparently does not help me much to comprehend the concepts behind and neither does reading the RFC. Hence I turn for answers t... |
> I'm trying to learn how AES-128-CBC encryption works. ... My implementation of key wrapping
Key wrapping is a specific form of encryption. You don't necessarily need key wrapping to encrypt something. Using this RFC to learn about encryption is not the most straightforward way.
Also, the key wrap algorithm from... |
Where is the 2nd group's generator used in the KZG Commitment Scheme? |
Where is the 2nd group used in the KZG Commitment Scheme in case the 2 groups are not the same? |
Where & how is the 2nd group used in the KZG Commitment Scheme in case the 2 groups are not the same? |
Pairings allow to do "multiplications in the exponent". Therfore, a good candidate for where $G_2$ comes in is where there's a multiplication. The winner is $$Q(x)(x-b) = F(x) -c$$.
The polynomial equality required for verification can be computed by:
$$e(Q(a)G_1, (a-b)G_2) \stackrel{?}{=} e((F(a)-c)G_1, G_2).$$
A... |
Imagine a channel where initial secret for deriving of actual key established with ECDH.
Like, first that shared secret used to derive a temporary key with some default parameters (salt, iterations) embedded into software.
Then this channel used to exchange random parameters specific to each direction (Alice sen... |
This is about the [KZG Polynomial Commitment Scheme](https://www.iacr.org/archive/asiacrypt2010/6477178/6477178.pdf)
In Section 2, it's written
> We use the notation $e : \mathbb G \times \mathbb G \mapsto \mathbb G_T$ to denote a symmetric (type 1) bilinear pairing.The choice of type 1 pairings was made to simp... |
> In essence, is it enough to send parameters for derivation of next IV with message, at least for some time, or it is mandatory to change both IV **and** key periodically if AES-GCM used?
The requirement with GCM is that you never use the same (key, IV) pair to encrypt two different messages.
The only other requ... |
I'm working on a challenge like this:
```python
def weird_func(x)
enc_flag = [(a + b*i) % n for i in FLAG]
return bytes(enc_flag).hex()
```
Although I know the FLAG prefix which is ```flag{```, without knowing `a,b` and `n`, I find it hard to calculate the whole FLAG. Only `p` is given in hex. I tried to ... |
I'm working on a challenge like this:
```python
def weird_func(x)
enc_flag = [(a + b*i) % n for i in FLAG]
return bytes(enc_flag).hex()
```
Although I know the FLAG prefix which is ```flag{```, without knowing `a,b` and `n`, I find it hard to calculate the whole FLAG. Only `enc_flag` is given in hex. I tr... |
Pairings allow to do "multiplications in the exponent". Therefore, a good candidate for where $G_2$ comes in is where there's multiplication. The winner is $$Q(x)(x-b) = F(x) -c.$$
The polynomial equality required for verification can be computed by:
$$e(Q(a)G_1, (a-b)G_2) \stackrel{?}{=} e((F(a)-c)G_1, G_2).$$
**... |
Monoalphabhatic Random Subsitution Cipher is pretty hard to crack compared to Ceasar Cipher especially through brute force but using frequency analysis, provided enough cipher text is easy.
But what if key for the subsitution changes lets say every 16 characters. Then there wouldn't be enough cipher text for frequ... |
How to break Random Subsitution Cipher that changes key every 16 characters? |
Monoalphabhatic Random Subsitution Cipher is pretty hard to crack compared to Ceasar Cipher especially through brute force but using frequency analysis, provided enough cipher text is easy.
But what if key for the subsitution changes lets say every 16 characters. Then there wouldn't be enough cipher text for frequ... |
I am working on TLS 1.2 Cipher TLS_DHE_RSA_WITH_AES_128_GCM_SHA256, After send the application data server throws an error message Encryption alert (21).
I have mentioned the parameter shard by the server given below.
Decryption key: ab98fbfabe869b008697b9f62b8f59ee7a3165db6a0fdc37e2bac41d73995889
nonce: f53672195e... |
We know that we can factor integer $n = pq$ when we know that $p\oplus q$, where $\oplus$ means xor. If we know $\lfloor \sqrt{p} \rfloor \oplus \lfloor \sqrt{q}\rfloor$, can we factor $n$? |
I am working on TLS 1.2 Cipher `TLS_DHE_RSA_WITH_AES_128_GCM_SHA256`, After send the application data server throws an error message `Encryption alert (21)`.
I have mentioned the parameter shard by the server given below.
```
Decryption key: ab98fbfabe869b008697b9f62b8f59ee7a3165db6a0fdc37e2bac41d73995889
nonc... |
> I am doubting the file format (I am using ASCII when using the test suite). However, is it correct to save them directly as a text file from MATLAB or should some special characters be used for the test suite to recognize them as ASCII format?
According to the [nice manual §5.4.1][2]
> Files should contain binary... |
> I am doubting the file format (I am using ASCII when using the test suite). However, is it correct to save them directly as a text file from MATLAB or should some special characters be used for the test suite to recognize them as ASCII format?
According to the [nice manual §5.4.1][2]
> Files should contain binary... |
> I am doubting the file format (I am using ASCII when using the test suite). However, is it correct to save them directly as a text file from MATLAB or should some special characters be used for the test suite to recognize them as ASCII format?
According to the [nice manual §5.4.1][2]
> Files should contain binary... |
I'm working on a challenge like this:
```python
def weird_func(FLAG)
enc_flag = [(a + b*i) % n for i in FLAG]
return bytes(enc_flag).hex()
```
Although I know the FLAG prefix which is ```flag{```, without knowing `a,b` and `n`, I find it hard to calculate the whole FLAG. Only `enc_flag` is given in hex. I... |
> I am doubting the file format (I am using ASCII when using the test suite). However, is it correct to save them directly as a text file from MATLAB or should some special characters be used for the test suite to recognize them as ASCII format?
According to the [nice manual §5.4.1][2]
> Files should contain binary... |
> I am doubting the file format (I am using ASCII when using the test suite). However, is it correct to save them directly as a text file from MATLAB or should some special characters be used for the test suite to recognize them as ASCII format?
According to the [nice manual §5.4.1][2]
> Files should contain binary... |
I'm making a cloud-based service. So, basically, my users will be able to upload files (any type of files) and they will be uploaded to a server. I am aware that I have two options:
- Upload the files first and let the back-end handle the encryption
- Encrypt the files first and upload then to the back-end
I ... |
What's the best encryption algorithm for storing files on a server? |
If order of the cyclic group on which discrete logarithm is done is $2q$ where $q$ is a prime such that $2q+1$ is a prime, then using square root identification we can get the lsb.
How about if the order is $2^rq$ where $r\in\mathbb Z_{\geq1}$, can we extract the least significant $r$ bits in polynomial time? If so,... |
> If order of the cyclic group on which discrete logarithm is done is $2q$ where $q$ is a prime such that $2q+1$ is a prime, then using square root identification we can get the lsb.
Two things:
- That's true only if the 'base' your compute the discrete log on is a quadratic nonresidue (for example, a generator).... |
> If order of the cyclic group on which discrete logarithm is done is $2q$ where $q$ is a prime such that $2q+1$ is a prime, then using square root identification we can get the lsb.
Two things:
- That's true only if the 'base' your compute the discrete log on is a quadratic nonresidue (for example, a generator).... |
Generally you can use AES in any secure mode of operation for that. AES is usually accelerated on the CPU, which means it is probably easily fast enough, while taking up little compute time. If you are dependent on a software implementation then ChaCha20 would be a better choice. For just keeping the data confidential ... |
Generally you can use AES in any secure mode of operation for that. AES is usually accelerated on the CPU, which means it is probably easily fast enough, while taking up little compute time. If you are dependent on a software implementation then ChaCha20 would be a better choice. For just keeping the data confidential ... |
Imagine a channel where the initial secret for deriving of the actual key is established with ECDH.
First, that shared secret is used to derive a temporary key with some default parameters (salt, iterations) embedded into the software.
Then this channel is used to exchange random parameters specific to each dire... |
I have given three points $ P $, $ Q $, $ R $ on Twisted Edwards Curve over prime finite field $ \mathbb{Z}_p $.
$$ ax^2 + by^2 = dx^2y^2 + 1 $$
I know about given points that point $ Q $ is doubling of point $ P $ and $ R $ is doubling of $ Q $. But I don't know the coefficient of curve's formula $ a $, $ b $, $ d $... |
How to get equation from given three points(with doubling) on twisted edwards curve over finite field? |
The [CLWE][1] problem (and [related][2]) talks about the hardness of finding the secret key $\vec{s}$, given polynomially many samples $(\vec{a},t)$, where $\vec{a}$ is sampled from the normal distribution, and $t=\gamma \vec{a}\cdot\vec{s}+e \pmod{1}$, where $e$ is also sampled from the normal distribution.
Is the... |
I'm making a cloud-based service. So, basically, my users will be able to upload files (any type of files) and they will be uploaded to a server. I am aware that I have two options:
- Upload the files first and let the back-end handle the encryption
- Encrypt the files first and upload then to the back-end
I ... |
As far as I understand, compressed public keys of secp256k1 can represent points either above or below the X axis, depending on whether they begin 0x02 or 0x03.
Am I correct in thinking that if you know a secret key for a public key beginning 0x02 you can trivially find the secret key for the identical public key, b... |
Does using only one sign of secp256k1 publc keys weaken security? |
> I am doubting the file format (I am using ASCII when using the test suite). However, is it correct to save them directly as a text file from MATLAB or should some special characters be used for the test suite to recognize them as ASCII format?
According to the [nice manual §5.4.1][2]
> Files should contain binary... |
> If you know a secret key for a public key beginning 0x02 you can trivially find the secret key for the identical public key, but beginning 0x03
Indeed, there's a simple relation between private keys $d$ and $d'$ for public keys $Q$ and $Q'$ differing only by sign as coded by the 0x02 or 0x03 prefix when in compres... |
> If you know a secret key for a public key beginning 0x02 you can trivially find the secret key for the identical public key, but beginning 0x03
Indeed, there's a simple relation between private keys $d$ and $d'$ for public keys $Q$ and $Q'$ differing only by sign as coded by the 0x02 or 0x03 prefix when in compres... |
I am interested in the practicality of using generic SNARK techniques to prove the following relation.
Let `E` and `E'` be two ElGamal ciphertexts. They have the form
`E = (E1, E2) = (g^r, M*PK^r)` and `E' = (E1', E2') = (g^r', M'*PK^r')`.
There is also a hash function `H`.
All of these are public: `E`, `E... |
Given the subgroup $H=\lbrace 1, \omega, \omega^2, \omega^3, ..., \omega^{n-1}\rbrace$ of order $n$, the Lagrange basis of this subgroup is given by the set of polynomials $\lbrace L_i \rbrace_{i=1}^n$ such that $L_i(w^k) = 1$ if and only if $i=k$ and $0$ otherwise.
The well-known interpolation methods gives $L_i(x... |
Why can't we use any random elliptic curve? What are the properties that need to be satisfied? |
How are elliptic curves designed for encryption purpose? |
Shamir's Secret Sharing GPL implementation called `ssss` got removed from Tails OS years back.
- Is Shamir's secret sharing still secure nowadays? Why was it removed from Tails OS?
- Is it true that the technical limit is a maximum of 128 characters? |
The [diffusion model][1], which is used by products like [Midjourney][2] and [Dall-E][3], trains AI systems to de-noise *(remove added randomness)* from data to infer what the original de-noised data is. That would seem to have direct applications to cryptanalysis. As such, **I wonder what views security folks have on ... |
How big of a threat are *diffusion model* based AIs to cryptographic systems? |
in the following pdf, several attacks on double key length triple des are deemed feasible at 2 to the power of 88/89 des calculations.
if we take the record of cracking des at 2 to the power of 56 calculation in 23 as the example, according to my estimate, this should take hundreds of years and definitly isnt feasib... |
How is it that the attack in this pdf is deemed feasible, at 2 to the power of 88/89 des calculations? |
in the following pdf, several attacks on double key length triple des are deemed feasible at 2 to the power of 88/89 des calculations.
if we take the record of cracking des at 2 to the power of 56 calculations in 23 or so hours as the example, according to my estimate, this should take hundreds of years and definitl... |
in the following pdf, several attacks on double key length triple des are deemed feasible at 2 to the power of 88/89 des calculations.
if we take the record of cracking des at 2 to the power of 56 calculations in 23 or so hours as the example, according to my estimate, this should take hundreds of years and definitl... |
You didn't attach a PDF, but I assume you're talking about Stephan Luck's work.
Your question appears to be "if $2^{56}$ level of effort takes almost a full day, why are we worried about something that might take circa $2^{88}$ level of effort?"
The point you're missing is that $2^{56}$ level of effort need not t... |
> Is it feasible that such systems, which are trained on the input-output tuples of specific cryptographic primitives, could discover distinguishers that are unknown to human evaluators?
That's plausible for weak cryptographic primitives, as found in hand ciphers and challenges. In black-box attack of an _unspecifie... |
Could anyone please help me explain this?
I am reading the article about TFHE ([Guide to Fully Homomorphic Encryption over the \[Discretized\] Torus][1]).
On page 31:
[![enter image description here][2]][2]
I don't understand why we need to scale to module 2N. What is the meaning of "multiplicative element ... |
What is the meaning of X is of order 2N in blind rotation of TFHE? |
Are cofactor $4$ and $8$ ECC schemes widely used in practical deployments such as those in cryptocurrencies?
Can you name some practical settings where there curves are used and cryptocurrencies where these are used (I checked bitcoin and it uses cofactor $1$ ECC and so I was not sure if other cryptocurrencies also ... |
Practical deployments of ECC with cofactor of elliptic curves $4$ or $8$? |
I read somewhere that TRNGs are better than cryptographic algorithms that generate pseudo-random numbers (PRNGs) because these algorithms are more energy intensive than TRNGs.
By low power devices, I mean things with limited computational capacity or limited power. Like a small IOT device.
Would there be any benefit ... |
Are TRNGs used in low power devices? Why? Which ones are the best? |
When I came to the topic of Ansible (Vault), when deploying secrets in Ansible and other passwords up to 128 characters Shamir's Secret Sharing would be an ideal solution I think:
- The secret is never in one spot
- The secret can be encrypted "on top"
- You can place the parts of the secrets on multiple servers w... |
Why don't basically all "clusters" and similar distributed systems use Shamir's secret sharing method? |
I read somewhere that TRNGs are better than cryptographic algorithms that generate pseudo-random numbers (PRNGs) because these algorithms are more energy intensive than TRNGs.
By low power devices, I mean things with limited computational capacity or limited power. Like a small IOT device.
Would there be any bene... |
Are TRNGs used in low power devices? Why? |
> The secret is never in one spot
No. When the secret is initially built, and when it is rebuilt and used, it's in one spot.
> Is Shamir's secret sharing secure nowadays?
Yes, for what it does: before the threshold of shares is met, nothing can be learned about the secret. As noted in [comment][1], that's agai... |
According to [Wikipedia][1], tropical cryptographic protocols are built upon tropical algebras, i.e., a semiring $(\mathbb{R} \cup \{\infty\}, \oplus, \otimes)$ where $x \oplus y = \min \{x,y\}$ and $x \otimes y = x+y$. Recently, several tropical algebra-based cryptographic protocols have been proposed, and they rely o... |
Could tropical cryptography become another candidate for post-quantum cryptography? |
> The secret is never in one spot
No. When the secret is initially built, and when it is rebuilt and used, it's in one spot.
> Is Shamir's secret sharing secure nowadays?
Yes, for what it does: before the threshold of shares is met, nothing can be learned about the secret. As noted in [comment][1], that's agai... |
> TRNGs are better than cryptographic algorithms that generate pseudo-random numbers (PRNGs) because these algorithms are more energy intensive than TRNGs
Random number generation in IoT devices is [necessary][1] and [challenging][2], with many [proposaled][3] solutions. However, [any][4] modern computing system [wi... |
> TRNGs are better than cryptographic algorithms that generate pseudo-random numbers (PRNGs) because these algorithms are more energy intensive than TRNGs
Random number generation in IoT devices is [necessary][1] and [challenging][2], with many [proposed][3] solutions. However, [any][4] modern computing system (incl... |
> TRNGs are better than cryptographic algorithms that generate pseudo-random numbers (PRNGs) because these algorithms are more energy intensive than TRNGs
Random number generation in IoT devices is [necessary][1] and [challenging][2], with many [proposed][3] solutions. However, [any][4] modern computing system (incl... |
> TRNGs are better than cryptographic algorithms that generate pseudo-random numbers (PRNGs) because these algorithms are more energy intensive than TRNGs
Random number generation in IoT devices is [necessary][1] and [challenging][2], with many [proposed][3] solutions. However, [any][4] modern computing system (incl... |
I'm decently new to cryptography and am trying to wrap my head around zero-knowledge proofs and applications. One use case that I am trying to figure out a strategy for is the following:
I have some plaintext that I'm going to encrypt and give to someone. They can't decrypt the ciphertext but want to verify the hash... |
Suppose it is an Army Enigma I. Choose reflector UKW-B or UKW-C. Choose three rotors from I, II, III, IV and V. For each of the 120 reflector/rotors permutations, there are 17,576 starting indicator positions to test.
Menu
----
Ciphertext $\tt RRHKJ \ KNJXE \ UWNFO \ T$ has 16 characters. Crib $\tt WETTE \ RVORH... |
Suppose it is an Army Enigma I. Choose reflector UKW-B or UKW-C. Choose three rotors from I, II, III, IV and V. For each of the 120 reflector/rotors permutations, there are 17,576 starting indicator positions to test.
Menu
----
Ciphertext $\tt RRHKJ \ KNJXE \ UWNFO \ T$ has 16 characters. Crib $\tt WETTE \ RVORH... |
Suppose it is an Army Enigma I. Choose reflector UKW-B or UKW-C. Choose three rotors from I, II, III, IV and V. For each of the 120 reflector/rotors permutations, there are 17,576 starting indicator positions to test.
Menu
----
Ciphertext $\tt RRHKJ \ KNJXE \ UWNFO \ T$ has 16 characters. Crib $\tt WETTE \ RVORH... |
> TRNGs are better than cryptographic algorithms that generate pseudo-random numbers (PRNGs) because these algorithms are more energy intensive than TRNGs
Random number generation in IoT devices is [necessary][1] and [challenging][2], with many [proposed][3] solutions. However, [any][4] modern computing system (incl... |
> TRNGs are better than cryptographic algorithms that generate pseudo-random numbers (PRNGs) because these algorithms are more energy intensive than TRNGs
Random number generation in IoT devices is [necessary][1] and [challenging][2], with many [proposed][3] solutions. However, [any][4] modern computing system (incl... |
> TRNGs are better than cryptographic algorithms that generate pseudo-random numbers (PRNGs) because these algorithms are more energy intensive than TRNGs
Random number generation in IoT devices is [necessary][1] and [challenging][2], with many [proposed][3] solutions. However, [any][4] modern computing system (incl... |
> TRNGs are better than cryptographic algorithms that generate pseudo-random numbers (PRNGs) because these algorithms are more energy intensive than TRNGs
Random number generation in IoT devices is [necessary][1] and [challenging][2], with many [proposed][3] solutions. However, [any][4] modern computing system (incl... |
According to [Wikipedia][1], tropical cryptographic protocols are built upon tropical algebras, i.e., a semiring $(\mathbb{R} \cup \{\infty\}, \oplus, \otimes)$ where $x \oplus y = \min \{x,y\}$ and $x \otimes y = x+y$. Recently, several tropical algebra-based cryptographic protocols have been proposed, and they rely o... |
> The secret is never in one spot
No. I pure Shamir secret sharing, when the secret is initially built, and when it is rebuilt and used, it's in one spot. See comments for why this can be remedied, at least in part.
> Is Shamir's secret sharing secure nowadays?
Yes, for what it does: before the threshold of sh... |
> The secret is never in one spot
No. In pure Shamir secret sharing, when the secret is initially built, and when it is rebuilt and used, it's in one spot. See comments for why this can be remedied, at least in part.
> Is Shamir's secret sharing secure nowadays?
Yes, for what it does: before the threshold of s... |
Bob's public key is $B = G*b$. Alice's public key is $A = G*a$.
Alice encrypts her number $n$ with Bob's public key so Bob could decrypt it ($n$ is small enough to be brute-forced):
$$E = G*n + B*r$$ $$R = G*r_0$$ where $r_0$ is a random nonce. Alice sends $(E, R)$ to Bob.
Bob decrypts $(E, R)$: $$D = E - R*x$... |
Bob's public key is $B = G*b$. Alice's public key is $A = G*a$.
Alice encrypts her number $n$ with Bob's public key so Bob could decrypt it ($n$ is small enough to be brute-forced):
$$E = G*n + B*r$$ $$R = G*r_0$$ where $r_0$ is a random nonce. Alice sends $(E, R)$ to Bob.
Bob decrypts $(E, R)$: $$D = E - R*x$... |
I am trying to understand the design rationale of in place NTT in Dilithium. I know that how the splitting of polynomials is done but I cant seem to map this approach to the precomputed table of zetas that is present in the authors code. I have attached the array of values as well. Specifically speaking, is there a way... |
In dilithium (post quantum signature algorithm), how have the authors precomputed the table of zetas for NTT? |
Bob's public key is $B = G*b$. Alice's public key is $A = G*a$.
Alice encrypts her number $n$ with Bob's public key so Bob could decrypt it ($n$ is small enough to be brute-forced):
$$E = G*n + B*r$$ $$R = G*r_0$$ where $r_0$ is a random nonce. Alice sends $(E, R)$ to Bob.
Bob decrypts $(E, R)$: $$D = E - R*x$... |
Monoalphabhatic Random Subsitution Cipher is pretty hard to crack compared to Ceasar Cipher especially through brute force but using frequency analysis, provided enough cipher text is easy.
But what if key for the subsitution changes lets say every 16 characters. Then there wouldn't be enough cipher text for frequ... |
Bob's public key is $B = G*b$. Alice's public key is $A = G*a$.
Alice encrypts her number $n$ with Bob's public key so Bob could decrypt it ($n$ is small enough to be brute-forced):
$$E = G*n + B*r$$ $$R = G*r_0$$ where $r_0$ is a random nonce. Alice sends $(E, R)$ to Bob.
Bob decrypts $(E, R)$: $$D = E - R*b$... |
We can prove the security of a cryptographic scheme in standard model and non-standard model.
Standard models like using some computational assumptions, on the other hand, non-standard models like random oracle, generic group model. Right?
I've seen in a paper [[CGKV18][1] ,page 10] the term $\color{blue}{static}... |
What does the "static" assumption mean? |
> I read somewhere that TRNGs are better than cryptographic algorithms that generate pseudo-random numbers (PRNGs) because these algorithms are more energy intensive than TRNGs.
Well, that depends which PRNG & TRNG is used of course. Earlier implementations often used the keystream generated using a lightweight stre... |
The MACsec standard (IEEE 802.1AE-2018) states "The number of SCIs (and hence the number of SSCIs) is ultimately limited by the maximum number of current members in a group CA that MKA can support (less than 100) but is likely to be further limited by the port-based network control application (see Clause 7 of IEEE Std... |
What is the maximum number of current members in a group CA that MKA can support? |
Does any encryption/decryption algorithm supports linear decomposition? |
This would be a weakness and has been investigated under the name *does DES form a group*?
See [question and answer here][1]. A secure cipher should not have this property.
[1]: https://crypto.stackexchange.com/questions/75120/why-is-double-encryption-thats-equivalent-to-single-encryption-no-better-than-s/751... |
I am trying to fully separate RSA key pairs by breaking down $(N,e)$ for public part and $(N,d)$ for private part. From my understanding of RSA signature process, the message to be signed is digested at first (using e.g., SHA256) and the digest is then encrypted using private key. The receiver of the message then calcu... |
Why does OpenSSL RSA signature need the public exponent? |
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