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Is any concrete and real examples of CCA-attacks in recent history.
I'm aware about examples of WW2, but I'm more interested to modern examples in a digital context (for example against OFB, CBC).
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In the usual definition of security for message authentication codes, we let an adversary $A$ have access to an oracle for $Mac_k(.)$. However, if we consider that there exists a more powerful type of adversary $B$, that is also able to query an oracle for $Vrfy_k(.)$, how can we redefine the notion of security?
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Having just finished reading The Code Book by Simon Singh, which I found extremely illuminating, nevertheless I remain deeply puzzled about one aspect in the book regarding the one-time pad cipher. To cut to the chase, I don't understand how a would-be hacker would be able to break a given OTP cipher (thereby deriving ... |
I've found a post here: Small subgroup confinement attack on Diffie-Hellman
which says we can pick $k$ in this way:
And, as we know, $2$ will always be a prime-factor of $p−1$, therefore there will be a subgroup with two elements, that don’t generate anything besides themselves. Obviously the neutral element $1$ is in... |
I want to transform a semi random input to a shorter, uniformly random bit string. Assuming there is enough entropy in the semi random input, can I use a collision resistant hash function to extract randomness?
Update
After the first answer pointed out that the body of the question is not correctly asking the intended ... |
A JSON Web Token is supposed to have the following format:
token = encodeBase64(header) + '.' + encodeBase64(payload) + '.' + encodeBase64(signature)
When I use the jsonwebtoken node.js function to create a token:
jsonwebtoken.sign({username : "admin", password : "admin"}, publicKey, { algorithm:'HS256' });
It produc... |
Assume we want to transform semi-random $n$-bit inputs into shorter $k$-bit outputs computationally indistinguishable from uniformly random bit strings, and there is (in some sense, to be specified) enough entropy in each of the semi-random inputs towards this.
Under what condition(s) on a hash† function (and as far as... |
This question is related to this (but it is not the same).
Let's suppose I have a seed with an entropy of 1024-bits and hash it with a counter using a hash function with one-quarter of the seed size in bits as BLAKE2s (256-bits digest size).
I hash the seed with counters and XOR the result to plaintext.
As said in this... |
Let's suppose this:
Message is "I love crypto.stackexchange.com" (M)
Bob creates hash H1 with the message M and his private key (Priv)
Alice receives a message X, and hash H2 with message X and the public key of Bob (Pub)
So from 1=(,Priv) and 2=(,Pub) can we tell if =? (thanks to @fgrieu)
If it's not possible with a... |
Let's suppose :
I have a record/database (D) of 754 lines and each line correspond to a SHA256 hash.(Hn)
I hash all this record to a final and unique SHA256 hash like this : 1a3e6af379316c6b863318f9e23ad0588d7d845ea92f316779f36167fd359fb0 (F)
I know H34 (single entry of D) which is 9370d1f5ab2fe94f685039fc8a2bb8ec3c2a... |
Let $H: X \rightarrow \{0, 1\}^b$ denote a cryptographically secure, $b$-bits hash function on a set $X$. Let $H^*: \mathbb{P}(X) \rightarrow \{0, 1\}^b$ be a function on the power set of $X$ defined by
\begin{equation}
H^*(\{x_1, \ldots, x_n\}) = \sum_i H(x_i)
\end{equation}
where the sum is intended as wrapping addit... |
If two ensembles are statistically indistinguishable, we all know that they are also computationally indistinguishable, i.e., for any PPT algorithm, the probability to distinguish them is negligible.
My question is, what if the algorithm is not polynomial-time, but time-unbounded?
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First of all, I am a student, so even if most of you think it is a useless question, don't dishearten me as it is a platform for me to learn
I am using an AES code that has 3 Rows and 4 columns in its Shift Rows. Although I know in AES we have 4 rows and 4 column block. Then why is it working, I am not able to understa... |
Suppose we have the description of a group $\mathbb{G}$, a group of unknown order: the size of the group is unknown. For instance, an RSA group ($\mathbb{Z}^{*}_N,$ where $N=pq$ for unknown primes $p$ and $q$) or a class group. The prover wants to convince the verifier that for $h=g^x$ and that the exponent is non-nega... |
GMW is a pretty straight forward protocol for the setting of 2PC. It is still straight forward for the case of MPC except for the AND gate. I'm struggling to understand how to obtain a "good" communication complexity. To be more specific, the AND gate is described by the following function.
\begin{aligned}
c &=a \w... |
Let $n = P\cdot Q$ be the product of two safe primes $P = 2p+1$ and $Q=2q+1$.
Let $g$ be a generator of $C_{p} \subset \mathbb{Z}_n^*$, the multiplicative subgroup of order $p$. In other words, $g^p = 1 \pmod n$. (But $p$ is still secret of course.)
Would it weaken a RSA modulus if $g$ was public? It is easy to compute... |
I searched a lot for this information in search engines as well as taking a look in the SHAKE reference implementation.
If I decide to use SHAKE as a stream cipher, can I access a specific part of the keystream without having to generate previous data from the beginning?
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I read a website on The Pohlig-Hellman Algorithm for solving the DLP, in which it states that we can express $x$ as:
$x= a_0 + a_1p+ a_2p^2+...+ a_{e-1}p^{e-1}$, where $p^e$ is a prime factor of the order of the group.
We then can brute force all of $a_i$'s.
But my question is, if we can figure out all $a_i$'s, why we ... |
I was reading the Wikipedia page for SHA-256 (SHA-2) and came across the following statement:
For a hash function for which $L$ is the number of bits in the message digest, finding a message that corresponds to a given message digest can always be done using a brute force search in $2^L$ evaluations.
Why is this true... |
I am trying to closely follow the algorithm here (keeping the same variable names) and reconstruct the cryptosystem in Sage Math engine. It seems to work on parameters (N, p, q) = (11, 3, 31) but raises assertion error at the end on (N, p, q) = (11, 3, 29). Please see the code below:
N = 11
p = 3
q = 31 # fails for 29
... |
I'm trying to get my head around this scenario. I understand that a private key can be used for signing a message to provide authentication and public key can be used for encrypting and its corresponding private key can be used to decrypt it. I came across this scenario and Ive been trying to research why this scenario... |
Hashing a seed with SHAKE-256 and setting the output size to 1GiB it takes 6.5 seconds on my system:
$ time dd if=/dev/random count=40960 bs=1 &>/dev/null | shake256sum -N 8589934592 > /dev/null
real 0m6.497s
user 0m5.682s
sys 0m0.844s
/\ 165.2 MiB/s
SHAKE-256 can be used to generate keys of any size as an (exp... |
Let's suppose I have a 1MB high-resolution photo and I want to hash and create a 1536-bits key.
I know that I could just use SHAKE-256 as its a pre-enginered way for doing that.
There is also Skein that can emit outputs of any sizes (up to 2^64-1).
But Skein has a internal state of 1024-bits.
If I decide to use Skein t... |
It's given 2 plaintexts $m_1$ and $m_2$, and 5 different values of $n\quad\{n_1, n_2, n_3, n_4, n_5\}$ which are generated as follows:
$n_1$ is a a product of two relatively small 128-bit $p$ and $q$ so its easily factorable by a simple database look-up,
$n_2$ is the value of $p_1*p_2*q_1*q_2$, with $p_2$ being the ne... |
A cryptography course covered among others following questions:
arithmetic of polynomials over $GF(2^m)$ fields - polynomials division
elliptic curves over field $GF(2^m)$
In scope of former point students were told polynomials product needs subsequent division by irreducible polynomial in order to stay in given orde... |
I am making a program that verifies the avalanche effect for the SBOX of the AES block cipher for a certain number of iterations. This program changed one bit randomly in one of the elements of the input list (state) and then applied the subBytes operation to both the original and modified lists. After that, it counts ... |
I'm going to guess the latter, but just wanted to ask here.
I want to have a relatively short signature, and my goal is to take a substring of the resulting hash.
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In ZCash, Monero etc, the sender/receiver addresses as well as transaction details are hidden. However, with a viewing key, a third party can see the exact details of the transaction or all transactions done by a certain address. How are things like these achieved? Any direction or sources are appreciated.
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Let's say I have a 32-bit number and a primary secret key and want to encrypt it without increasing the size.
this is how I'm doing the encryption,
I create an HMAC hash using the primary key and current date as data
Then XOR input bytes with hash bytes a few times
for (let offset = 0; offset < hash.length - 4; offse... |
When I read the work of Dodis et al. ref1, it looks as if I have encountered a simple logical bug. (I'm not concerned with the details of secure proof techniques, but with the logic of reasoning.)
In this article, Dodis et al. demonstrate the one-way security of ROM-AI (ROM with auxiliary information). The core idea is... |
I am following the NTRUEncrypt cryptosystem as described on the wikipedia. I have implemented it in Sage Math engine (with small problems along the way, but in the end - succesfully resolved) and the system works just as expected.
I have noticed an interesting publication regarding expanding NTRU to higher order algebr... |
There seem to be two ways to RSA-encrypt using .Net:
EncryptValue (which doesn't seem to pad the plaintext).
and
Encrypt (which does).
I was wondering, since what I'm encrypting is a cryptographically secure (cough...) AES key, do I need it to be padded by an official padding scheme? Assuming, of course, that the lengt... |
Let's suppose I want to encrypt a 10GiB file but I don't want to use a One Time Pad, just a 1MiB key taken from /dev/random (in Linux).
I know that the key should not be repeated, but is it possible to do a form of pseudo-OTP by using the same key across the entire plaintext?
I thought in a scheme: Hash each 64-byte pi... |
If I encrypt a 1MiB file with AES-CBC (or any other cipher) and XOR a 128KiB of (truly) unpredictable random data repeating until the end of file, will I have a security of 1048576-bits (128KiB*8)?
This question is a little weird, but I would like to know if this scheme has a security flaw (maybe known-plaintext attack... |
I'm trying to understand the implication of the Binder Keys in in a TLS 1.3 resumed handshake. The TLS 1.3 RFC provides an additional RFC with example traces to validate all the math in a TLS 1.3 handshake. I'm using this example trace to try to re-create the binder keys to understand what went into them.
One of the e... |
In BLAKE2X paper it is said:
BLAKE2X adds a constant overhead of $\lceil\ell/64\rceil$ (resp. $\lceil\ell/32\rceil$ compression function calls compared to the underlying 64-bit (resp. 32-bit) BLAKE2 hash. For example, to compute a 1056-bit (132-byte) hash as required in Ed521 signatures, BLAKE2X adds† $\lceil132/64\rc... |
Can a file encrypted with a hashing algorithm (like SHA-256) be equally secure as a symmetrical algorithm (like AES)?
This is how it could be done using a password (this is the most simple example, please don't suggest optimizations, it's just the concept):
Generate random looking binary data of the same length as the... |
In this journal paper related to physically unclonable function (PUF) [1], the authors used NIST 800-22 test to check if the bitstreams generated by their PUFs are random, which is described as follows:
NIST tests are performed using 60 sequences of 128 bits each such that 7680 bits (i.e., digitized keys) collected fro... |
I understand that it is easy to compute eth root in Z(P)* but what about with Z(N)? I know that it requires the factorization of N but what does that actually mean? What is an example of calculating the eth root in the set Z(N) (the set of all elements coprime to N)
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I was looking at the archives for the British national cipher challenge, and a modified version of an ADFGVX cipher came up twice (2003 2011), with block transposition instead of columnar transposition.
The question I has is what is this referring to? I tried finding information about block transposition, but there app... |
Are there examples (in code, or a blog post / writeup) of using Noise and Signal together?
Here is a link to Noise.
For example, using the Double Ratchet per each message to achieve forward secrecy, but leveraging Noise as a foundation for its patterns of initial key exchange. Both Noise and Signal are well-studied and... |
I have 3 Pailler encryption p1=E(x1;r1),p2=E(x2;r2);p3=E(x3;r3) such that
x1*x2(mod n)=x3. P(Prover) knows (x1,r1);(x2,r2);(x3,r3).
Can I design a ZKP(interactive & non-interactive) for P to convince V(verifier) that values hidden by p1,p2,p3 satisfy x1*x2(mod n)=x3.
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I can generate a key of any security in bits with any hash function from random source with enough entropy by using the following scheme:
$$H(00||S) || H(01||S) || H(02||S) || H(03||S) || \cdots$$
/\ H is the hash, S the seed and 00, 01, 02 the counters.
BLAKE2X hashes are computed as follows:
$$\operatorname{B2}(0,64,... |
I am a Bitcoin enthusiast, but I have never been formally trained in the study of computer science and cryptography.
Recently, I tried a new way to encrypt my private key: I wrote it down on a paper, and used my camera to take a photo of that paper sheet. Then, I encrypted the photo from pgp4win.
Then I noticed that th... |
The title is a mouthful, allow me to explain my situation.
I have a SaaS with many users.
When new users join the platform, I want to create a cryptographic keypair for them (Ed25519).
But I don't want to have any knowledge about their private key.
This means the keypair must be generated and stored by a third-party s... |
I have some doubts regarding AES weakness and AES cryptanalysis. While it is relatively simple to find Cryptanalysis info on previous ciphers, I get confused about understanding various types of Cryptanalysis attacks on AES.
So far, for example, I've found that AES's weakness could be in its algebraic structure. Anyone... |
If an attacker has a database of 1,000 users' hashed passwords which are hashed with SHA-256 with a 128-bit salt and all of these users used 10,000 common passwords. How many hashes will the hacker need to do to recover all passwords?
I was thinking it would just be 1,000*10,000 = 10,000,000 hashes but I am not sure ho... |
Is there any PKE scheme that is IND-CPA secure (in a standard model, not RO) under a search problem?
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I have been reading about Zero Knowledge Proof (ZKP) protocols for a while now. Among the applications I have seen the most is authentication (https://ethereum.org/en/zero-knowledge-proofs/#authentication). But in practice it is not used; why?
I have also been looking for why these protocols are not used in authenticat... |
I'm protecting communication between some microservices using public/private key encryption, where the sending container has a public key and the receiving container has a private key. This both verifies the sender (only sender has the public key via a credential manager), and protects the data in case it may be buffer... |
I'm trying to implement the 1st round attack on RC4 stream cipher according to Attacks on the RC4 stream cipher. For now I am interested in section 4.2 Attack on other key bytes. It works really fine for all the bytes of the random key of length 8, except the 2nd byte. The needed value t is always the second frequent o... |
I know restricting access of a file, is a important measure of security.
If we read the Payment Card Industry's Data Security Standard (aka PCI-DSS), we can see a requirement where control access must be applied to mitigate any risk of a sensitive encrypted data be leaked from the system.
Other important requirement de... |
I've been reading for Pohlig-Hellman Algorithm on Elliptic Curve.
My question is, why the simultaneous congruence gives the answer we want, could somebody please provide a proof of it?
i.e., why
\begin{align*}
x \equiv x_i \mod p_i^{e_i}, \forall i\in \{1,2,...,n\}
\end{align*}
Reference: https://risencrypto.github.io/... |
If the Substitution box is 1 to 1 (a specific value can only ever be a specific box value), and the contents of Rijndael S-box is public, how does this offer any additional security?
With AES the frequency of a letter isn't a concern so what other reason is there for this substitution? An explanation fitting for a novi... |
I'm reading headlines on the tune of "…bring zero-knowledge encryption to file storage". Googling "zero-knowledge encryption" returns statements like "cloud storage or backup providers know nothing (i.e. have “zero-knowledge”) about the data you store on their servers".
Is there some academic definition of "zero-knowle... |
I ask because some vendors of HSM try to avoid the export of wrapped secret key from HSM to insecure storage – storage that does not belong to these vendor’s HSM infrastructure.
For example, Thales prefer to backup keys to another Thales HSM – most of their documentation is about cloning between their devices.
But Tha... |
We know that SHA-1 is susceptible to collision attacks, but what about pre-image attacks such as poisoning torrents?
|
I want to prove that for every pseudorandom function $F: \{0, 1\}^n \times \{0, 1\}^n \rightarrow \{0, 1\}^n$ and for every polynomial $p$ such that $p(n) > 1$ for every $n$ it is possible to construct, starting from $F$, a pseudorandom generator $G$ having expansion factor equal to $l(n) = p(n) \cdot n$.
I fixed a PRF... |
I want to compute the multiplicative inverse of 0x2 over $GF(2^{233})$ in hardware.
To do so, I compute $a^{-1} = (a^{2^{m-1}-1})^{2}$. Here's the result of that computation:
0x10000000000000000000000000000000000000002000000000000000000 (where the left-most 1 is bit index 233, not 232).
I verify that I get 1 by multipl... |
I implemented the Pohlig-Hellman algorithm for the general case following Wikipedia but it only seem to work for prime powers (which is what the limited case is meant to solve).
My implementation follows wikipedia exactly: https://gist.github.com/nickponline/2ef6f3456ed6c423239a334c98728324
Some examples where it fails... |
If I have the password and hash will I be able to find out the Hashing algorithm and salt used. What tools can I can use? Will hashcat work?
|
I am working on a project that uses PAKE (SRP) for authentication. When we send the M1 to the server we are encrypting the payload using AES-GCM. I mention SRP only to set the context:
A message is being sent to the server with content we want to protect
The client and server have a unique (one-time) symmetric key sha... |
In the paper GM18, they say that the sampling algorithm, SampleG, is shown in Figure 2. It takes as input a modulus $q$, an integer variance $s$, a coset $u$ of $\Lambda^{\perp}(g^T )$, and outputs a sample statistically close to $D_{\Lambda^{\perp}_u(g^T),s}$. SampleG relies on subroutines Perturb and SampleD where Pe... |
So I get how it works for inputs shorter than $512$, but as for larger inputs "In the case where the remaining input data is exactly $448$ bits long, an entire extra block would need to be added for the padding." what do they mean by the 'remaining' input data is exactly $448$ bits long? if input was like, lets say $50... |
I'm reading the fourth edition of "Cryptography: Theory and Practice" by D.R. Stinson and M.B. Paterson.
In the book, they have mentioned the concept of "collision-resistant hash" and I've stumbled upon the following question from another source:
Is there a collision resistant hash function $h(x)=h_1(x)\oplus h_2(x)$ ... |
so i have function to decrypt aes ctr. but when i tried to decrypt, the result i got from plaintext is type bytes. i want to get the result of plaintext using decode, because when i encrypt it, i was encode it first.
here's my encrypt func:
def encrypt(key, pt):
plaintext = read_file(pt)
if isinstance(plaintext... |
In mpz_nextprime(), after some sieving with small primes, an MR test function is called, with the number of trials set to 25 (https://github.com/alisw/GMP/blob/master/mpz/nextprime.c#L118):
if (mpz_millerrabin (p, 25))
goto done;
But then in mpz_millerrabin(), for large enough candidates (candidates bigg... |
For my own project and the fun of it I have created an algorithm that turns plain text into cipher by interacting between entered text and a given password. My question is, in this instance, does the password count as what is known as a key, or is a key something entirely different?
|
A user of this forum answered in one of my questions and said that if the IV is kept secret in multiple encryption with CTR mode, the cost of breaking the scheme is $${2^{2 l_{key}}} 2 \cdot {2^{l_{iv}}}$$
Can the encryption operation in multiple-encryption with CTR mode be replaced by a non-cryptographic operation ass... |
I have a question about Cryptocurrency wallets like Metamask (soft) or Ledger (hard).
How is a 12 or 24 word seed phrase enough to show the same crypto addresses in any crypto wallet that supports the same standard (ie. BIP-39). Can someone unravel this for me / us?
Would it be this:
seed phrase with its 2048^(12 or ... |
AES-256 in XTS mode has 32x16 (512) bytes of blocksize but there are some other wide-block modes of operation such as WCFB which accepts any block size.
My question is:
What is the maximum acceptable block size for disk encryption? "Acceptable" is ways of not having too much cons.
|
I have some questions about the Kyber paper, especially about Theorem 2 on page 6, which I would like to ask here. First of all I quote the following theorem from the paper and ask my questions afterwards.
Theorem 2. For any adversary A, there exists an adversary B such that $Adv_{Kyber.CPA'}^{cpa}(A) \leq 2 \cdot Adv... |
I have this couple of deterministic functions $G_1$ and $G_2$. Suppose at least I of them is a PRG. Take $G^*=G_1(x)$ xor $G_2(x)$ with the same $x$. I have to show whether this is still a PRG. I thought about this counterexample: if $G_1=G_2$ then $G^*$ cannot be a PRG but my teacher said then $G^*$ isn't interesting.... |
I've been reading this set of notes on some topics in MPC and am having difficulty understanding the transformation the authors make in order to reduce the round complexity of the GMW protocol through applying garbled circuits. In particular, the goal is to make the round complexity of GMW independent of the depth of ... |
I am wondering how to use and expand keys during the Decryption.
Let’s say we have an initial key (128bits): 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F 70
So we get: w[0] = (61 62 63 64), w[1]=( 65 66 67 68),w[2]=( 69 6A 6B 6C),w[3]( 6D 6E 6F 70)
Then with the g () function, we get:
Circular byte left shift of w[3... |
LFSR-12 with poly $x^7+x^2+1$ and LFSR-19 with poly $x^{11}+x^5+1$ are used to produce
8 bit of output each, output is then added together modulo FF
(LFSR-12+LFSR19)mod FF
I know first 8 bytes (-> 8 cycles of registers) of this sum. I am pretty sure there is better solution than just brute force - which is currently ... |
OK, so I know that this is somewhat really basic in "post-quantum discourse", but unfortunately I did not find any textbooks/entry level papers specific to the topic of reductions in the quantum setting.
It seems that there are two main caveats regarding quantum adversaries:
The possibility to ask a "superposition que... |
Given two functions f,g we have to construct h; such that h is one way function. Either f or g is a one way function. We don't know which one is a one way function. Both f and g are defined over X-> Y
|
I'm having a problem in a RSA challenge. I already had p, and q is calculated based on p.
(100000000**(p-1) -1)%p
q is the nearest prime to this number.
I knew that my comp will take a huge time too compute this (Don't know what time it would take). So can you guys suggest some ways to deal with this large number. Man... |
I wasn't sure if this question is more suited for SE.Math or not; please tell me if I should move it.
For its mpz_nextprime() function (find the next pseudoprime following the given number) GMP uses an interesting variation of the Sieve. In order to weed out multiples of small primes before applying slower tests (Mille... |
Suppose I want to take advantage of hardware accelerated symmetric encryption like AES and use it to compute a “hash”. How collision resistant would it be if I’d take the IV + last N blocks of an AES CBC transformation and use it as my hash. What would be good
Values for N?
In my hypothetical use case I am not immediat... |
In trying to implement mental poker, can all players agree on a standard set of 52 points on the curve corresponding to each card, and then to "encrypt" a card you just multiply it by a scalar which is your encryption key? (and to decrypt, multiply by the scalar's inverse modulo the group size)
|
I am currently trying to reverse engineer a piece of software that uses a seemingly-custom encryption algorithm.
After disassembling the decryption part of the code, I've come up with the following code that decrypts the data file just as well as the original software:
void decrypt_one_run(uint8_t* four_bytes_to_decryp... |
About Rabin Signature link
According to this paper, the person who wants to sign a message M first appends a random byte string U.
=> M_new = MU
Then uses a compression function to get c = Compression_function(MU)
Then solves the equation for x, x(x+b) mod n = c mod n.
Then the signature is (U,x) pair.
My question i... |
I had an idea to make XEX mode parallelizable at CPU level.
Let's suppose I take an IV, XOR with random data, encrypt, XOR again with another data, and XOR on the plaintext
Would this encipherment scheme be valid? Would it be secure?
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I've found this question from 2014 on Key Whitening: How exactly does key whitening manage to increase security? where is said that AES applies key whitening internally by adding a sub-key prior to the first round and after the last round.
Isn't key whitening applied to each round in AES?
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can someone explain to me why django saves the hash in the database asargon2$argon2id$v=19$m=102400,t=2,p=8$... and not $argon2id$v=19$m=102400,t=2,p=8$...?
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The definition of Bilinear pairing is shown here
Could you given an simple numerical example of Bilinear pairing? It would be very helpful for me to understand
|
I want to encode my plaintexts as points on some given elliptic curve $E$ defined over a finite field $F_q$. Suppose I want to use Koblitz's method. Does the size of the message I want to encode matter? Can I encode the message in the size I want? What should I do with very long messages?
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I am planning to encrypt multiple values using a 16 byte IV that I'm generating from the below scheme. My seed is a 32 byte value generated from hashing a password and salt is an 8 byte counter (i.e. salt is easy to predict for an outside observer).
iv = sha256(seed, salt)[0:16]
Intuitively this should be equivalent to... |
Does it work if we try to construct a device (e.g., for counting purpose in several remote branches of a company) using a self-containing digital signature key enclosed in a tamper-proof hardware to make sure that the operations transcript of that function could be verified? (the transmitted report/transcript of the co... |
The proof of Lemma A.1 of the paper "FHE over the Integers" (Page 21-22) states that the absolute value of the rightmost term of
$c=p\cdot (kq_0+\sum_{i\in S}{q_i})+(m+2r+k\cdot2r_0+\sum_{i\in S}{r_i})$
is at most $(4\tau +3)2^{\rho}<\tau 2^{\rho+3}$.
We have $|k|\leq\tau$ and $|r_i|\leq 2^{\rho}$.
In addition, it is m... |
Sorry if this is a duplicate but, to be honest, I don't even know how to search for an answer to it.
I'm working in an environment in which I cannot use streams to encrypt data (React Native using the react-native-aes-crypto module).
Unlike Java where I can use something like cipher.update(buffer) (where cipher is an j... |
I'm trying to practice and to understand possible scenarios and the basics of symmetric encryption schemes. For the scenarios I listed below, I am not 100% sure of scenarios 1 and 3.
A symmetric encryption algorithm using non-random/predictable IV that is CPA secure.
I do not think this scheme is possible. For examp... |
Let F be a pseudorandom function. Check if if $F_1(k,x) = F(k,x) \oplus x$ is pseudorandom( $\oplus$ is bitwise XOR).
I found this question in a book. I am not sure how to proceed :
$F_1(k,x) = F(k,x) \oplus x \implies F(k,x) \oplus F_1(k, x) = x$
Now do we assume that we know $F(k,x), F_1(k,x)$ ? Because if we do I fo... |
I want update in place for sorted element list and proof for accumulator encoding of only element updated. I try to find technique similar to this, but only GCTI pop up and similar methods.
It must get elements in order of sorted list, replace ith element ($e^i$) with update list element ($e'^i$) to make new accumulati... |
I have been studying C/C++ and I read that if one wants unpredictable random data in a program, it is needed that a random generation function be supplied with truly and unpredictable random data (as of /dev/hwrng).
But this confused me because for cryptographic things a normal and non-cryptographic PRNG should be avoi... |
I'm currently trying to implement compact proofs of retrievability that are publicly verifiable by RSA as described in this paper Compact Proofs of Retrievability in GO. I'm currently struggling on page 26 with the following equation:
$$
σ_i \leftarrow \left(H(\text{name}\mathbin\|i) \cdot \Pi_{j=1}^s u_j^{m_{ij}}\righ... |
How do you calculate the digraphic and trigraphic IOCs and the same expected IOCs? I'm aware of the formula for calculating the single letter IOC which is given at this formula but I can't find the formula for the higher orders.
Is it simply the sum of frequencies ( $F_i(F_i − 1)$ or $F_i \times F_i$ where $F_i$ is eac... |
Brzusk et al. introduced the state-separation proof technique to tame complexity in game-based security proofs. The framework allows for modular, easy to understand, and reusable proofs. It has been applied to real-world protocols, like in this paper on the security of the TLS 1.3 key schedule. Additionally, this forma... |
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