-3
votes
1answer
82 views

RSA when n= 2360221 and encryption = 5 find decryption key d, when M =1234

when n= 2360221 and encryption = 5 find decryption key d,and Cipher text C when M =1234
2
votes
1answer
61 views

How to detect what crypto-method is used by Filecoder.Q?

I have 2 different images, one original, and one locked by a malware detected by eset as "Win32/Filecoder.Q". How to detect the encryption method that is used and the key, that is not using any ...
-1
votes
0answers
33 views

How to solve this public-key cryptography system? [closed]

I need to solve this problem: someone know where I can find info for this? I have google'd around but can't find too much, those $N, I, J, C$ variables confuse me.
3
votes
1answer
89 views

Trying to understand textbook exercise question regrading RSA

I am preparing for the final exam in my Data Security class so I am trying to read and understand the textbook's exercise questions. Any hint would be great. Question (Exercise 9.14 of textbook): ...
0
votes
1answer
34 views

Synchronous Stream Cipher Problem

Hello I am facing a problem trying to solve this question in the picture. Does anyone know how to produce the mentioned 32-bits of the key stream? The plaintext in this case is ...
1
vote
1answer
49 views

Trying to udnerstand textbook sample solution

I am preparing for the final exam in my Data Security class so I am trying to read and understand the textbook's exercise questions. The sample solution at the end the textbook is more like a hint ...
-1
votes
0answers
28 views

How to vary bit length of prime numbers in RSA by using MATLAB? [closed]

Please Can any one Tell me how to vary bit length of prime numbers of RSA cryptography algorithm in MATLAB.When i am considering more then 16 bit length of prime numbers Its not working. So can any ...
0
votes
1answer
44 views

Are collision-resistant hash functions even possible? [see description] [duplicate]

Surely there can be no real collision resistant Hash function since hash values are of finite size which means there are finitely many of them, but there are an infinite number of messages we could ...
1
vote
1answer
55 views

what is meaning of operator “ := ” in cryptography?

I've seen := used in several cryptography papers where the this symbol has been used instead of assignment operator ($ \leftarrow $ ) or equal sign (=), but never with an accompanying explanation. ...
0
votes
0answers
40 views

signature, hashing schemes

I have 20 friends. we create message(s) (1...i) and tar them up with a file messages.hashes(1..i). We sign these tars with our ...
0
votes
0answers
8 views

SAM module in Payment transactions & cryptogram key storing

As you know because of low security factors,General MCU's are not appropriate choice for storing Transaction or cryptograms keys.Therefor embedded systems developers used SAM modules for secure ...
0
votes
0answers
38 views

Find SHA256(secret||data) using SHA256(secret) and data

I need to find the SHA256 hash of s string like this: "part1-part2". I know the SHA256(part1), length of part1 and I know part2, but I don't know what is the contents of part1. Is there any chance I ...
3
votes
1answer
40 views

About ORAM initalization and running out of space

I have two questions about ORAM Since at the beginning,the server allocates unused storage for ORAM cient,there are no user's data in the storage.if now client access the storage the server will ...
1
vote
2answers
42 views

Key management and derivation - Allow changing of the passphrase

I'm working on a program, which allows encrypting files before storing it on a cloud service. Currently I'm trying to figure out how to derive and store the keys. First, I wanted to use a simple ...
2
votes
1answer
35 views

What implementation properties of a hash function prevent safe truncation? [duplicate]

Truncating a hash function's output should, in theory, not increase the likelihood of a collision more than you would expect based on the truncated output size. This makes sense when thinking about ...
1
vote
1answer
65 views

SHA256(RsaPrivateKey) == AES key?

I have an RSA private key (more specifically, an SSH key in Putty format, 4096bit) and want to use its SHA256 hash as an AES256 key, instead of using an independent newly generated AES key. Are ...
0
votes
0answers
24 views

What is transaction capacity of a POS using 3DES DUKPT?

I am looking for the transaction capacity of a Point-Of-Sale device using 3DES DUKPT. Once all keys derived from the future key set are exhausted (1M or 500K?), how will the POS be reloaded with a new ...
0
votes
1answer
35 views

Why hash function are used in digital signatures? [duplicate]

In the lectures I see, hash functions are always used when we want to sign a document $d$. My question is why they are used in digital signatures? Maybe, because it is more easy and fast to calculate ...
2
votes
1answer
27 views

Can multi-prime RSA be used to create an abuse-resistant lawful interception mechanism?

New to site so this may have been asked before: Can multi-prime RSA, i.e. where N is product of three or more distinct primes, be used for secure communication while allowing distinct authoritative ...
3
votes
0answers
34 views

Benchmarks for second round CAESAR competitors

I'm interested in how the second round CAESAR competitors stack up in terms of software performance against each other and against chacha20-poly1305 with both small and large messages. Sadly the only ...
1
vote
1answer
37 views

Attacks on schemes based on elliptic curves when the transmitted points are not on the curve

Some elliptic curve schemes require to send a curve point during the normal execution of the protocol. For example, ElGamal encryption and ElGamal signature require this. On the other hand, ECDSA does ...
2
votes
0answers
19 views

Creating an SPN cipher from ChaCha20 or Salsa20's double round function

Given that ChaCha20's building blocks have been also used to construct a hash function, can the double round function from either ChaCha20 or Salsa20 be used to construct a secure SP-network cipher? ...
0
votes
0answers
34 views

Squaring and multiply function in encryption algorithm [closed]

Could any one explain the square and multiply function in AES, Elgamal or RSA algorithm.
1
vote
0answers
24 views

Some confusions about Repeated Doubling Algorithm?

The following repeated point doubling algorithm is taken from the book Guide to Elliptic Curve Cryptography by D. Hankerson, A. Menezes, and S. Vanstone on page#93. Clearly, this algorithm is ...
2
votes
1answer
27 views

Steps to encrypt endorsements to a petition

I plan to circulate a petition, asking people to support it. This petition will reach a senior government official. In regular circumstances, people would support such petitions by writing their ...
0
votes
1answer
64 views

How secure is this logarithmic encryption algorithm?

How secure would the following logarithmic encryption algorithm be when tested under the same conditions as high end encryption algorithms (AES, RSA etc...). Note: For smaller text the text will be ...
3
votes
1answer
53 views

How to prove that an integer is hard to factorize when sampled from a known distribution

Suppose that an $n$-bit integer $c$ has been randomly drawn from a distribution $\chi$, whose description is known. Is there a general method to check if this particular sampling helps factorize $n$? ...
2
votes
1answer
30 views

On the security definition of password-authenticated key exchange

I found in all PAKE papers, the security is defined as something like this: Let $Succ(A)$ be the probability that an attacker $A$ successfully distinguished the session key from a random string. Then ...
1
vote
1answer
20 views

Crypto lib that use files instead of passphrase

I would like to program an application to allow people to encrypt files without using a password or pass-phrase but an arbitrary long file. I'm searching for a library that allows me to safely create ...
3
votes
1answer
45 views

what is the difference between proofs and arguments of knowledge?

What is the difference between proofs and arguments of knowledge in the context of zero-knowledge? I have read this sentence in this ePrint: It is useful to distinguish between zero-knowledge ...
1
vote
2answers
43 views

Using what we already know about the data to decrypt it?

Are there any methods or tools out there that let us use what we know about the data in order to crack the encryption? For example let's say I get access to an encrypted database file but I know ...
-1
votes
0answers
34 views
6
votes
2answers
80 views

What does the TLS 1.2 client finished message contain?

I am implementing TLS 1.2 and I'm stuck on the client finished message. My question is: what is the size and structure of a clients finished message in TLS 1.2 when using the ...
3
votes
0answers
29 views

is accessing elements of an array in secret order vulnerable to timing attack?

Suppose there is an array containing bytes 0...255. Suppose this array is shuffled using a key for random data. Since this is indexing the elements of a table using secret data, is it vulnerable to ...
0
votes
1answer
10 views

Can TLS session resumption work after client dropped connection & reconnected to server?

I'm developing a sensor node and investigating TLS/OpenSSL. The network the node runs behind could drop and reconnect a lot. The node has limited data plan so data overhead is the key where TLS ...
0
votes
2answers
43 views

Parallel file encryption and authentication for large files

For a cloud storage upload client I want to encrypt files during upload, so that they cannot be read by the cloud service provider or anyone who gains access to the account. I would like to use some ...
2
votes
3answers
291 views

What is the fastest block cipher in the (Intel) world?

In AES competition,Rijndael cipher obtained first rank and become Standard and Serpent, Twofish, RC6 and MARS obtained another ranks and I know that Serpent took second rank because it was slower than ...
4
votes
3answers
96 views

Is this Diffie-Hellman key exchange variant vulnerable to man-in-the-middle attacks?

As we all know, the Diffie-Hellman key exchange protocol without authentication is vulnerable to a man-in-the-middle attack. And if we use STS(Station-to-Station protocol) instead, it would be secure. ...
1
vote
1answer
32 views

Can I always derive a key pair from password+salt with libsodium?

I'm using libsodium to create public/secret key pairs from a password and salt combination by using crypto_pwhash_scryptsalsa208sha256 to generate a seed and ...
3
votes
2answers
60 views

GCM: use the same key:IV pair to encrypt file and filename

Using Java, I wrote a piece of code that encrypts a given file with AES in GCM mode of operation. So far nothing uncommon. Now I would also like to encrypt the filename, in the following way: ...
-1
votes
0answers
32 views

AES-CMAC in Java Card

Hello I am new to the world of Java card programming. Is there a proper way of doing an AES CMAC encryption? After researching I've hit a roadblock wherein I cannot find any example or samples of Java ...
1
vote
1answer
63 views

Analysis of DGHV Security

I want to know how security of DGHV can be breached using oracle and Binary GCD. As I study this paper : Fully Homomorphic Encryption over the Integers But I am not able to understand Section 4.1: ...
1
vote
0answers
54 views

Calculating the discrete logarithm

I'm given a prime number $p = 1217$ I'm also given the following equations: $$ 40 \equiv \log2 \pmod{64} \\ 63 \equiv \log3 \pmod{64} \\ 13 \equiv \log5 \pmod{64} \\ 13 \equiv \log2 \pmod{19} \\ 10 ...
0
votes
0answers
10 views

ACM 2004 World Finals, problem D: how can I solve this using a brute force method? [migrated]

https://icpcarchive.ecs.baylor.edu/external/29/2996.pdf How can I solve this using a brute force method in Python? I want to use a nested for-loop for the parameters I'm just not sure where to go ...
5
votes
2answers
190 views

Trapdoor and RSA (Schneier)

Disclaimer: I'm new to cryptography. Background: From Applied Cryptography (Bruce Schneier), page 30 of 2nd edition A trapdoor one-way function is a special type of one-way function, one with a ...
6
votes
1answer
62 views

Is the 'nonce' in bitcoin really a nonce?

Is the 'nonce' in bitcoin really a nonce? Reading definitions of nonce and salt it seems the number is used as a salt but the same value can occur in multiple blocks; there's no requirement or indeed ...
-1
votes
0answers
24 views

Pairing on BN curves, GMP code

Is it possible to write a small implementation of tate pairing using BN curves using GMP. It does not need to be efficient. I just want to understand the steps. Thank you.
0
votes
1answer
33 views

Possibility for same Private Key Generation in identity-based encryption

In private key generation of IBE scheme, private key is generated as follows: $SK_{ID}=s.H(ID)$ Suppose two servers use the same curve domain parameters. If PKG on server A generates private key ...
3
votes
1answer
64 views

Deriving AES key and HMAC key from shorter master key

I am working in .NET and as far as I can tell the only choice for key derivation is PBKDF2-HMAC-SHA1. SHA1's output size is only 160 bits. But I am implementing authenticated encryption and thus ...
0
votes
0answers
23 views

key hierarchy management and master key

I have this equation, $E_{K_{as}}(E_{K_{bs}}(K_{ab}))$ which means $K_{ab}$ is encrypted by $K_{bs}$ then whole packet is encrypted by $K_{as}$. I think the key structure is $K_{as}$ is the master ...

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