0
votes
0answers
6 views

pgp public rsa key format

I have been trying to use Go (I could post the code, but I think I posted enough already...) to generate a pgp rsa key. However every time I try to encrypt something with it, something fails. However, ...
0
votes
0answers
15 views

How can I tell how a text was encrypted? [on hold]

How can I tell what encryption method was used to encrypt this text below? I noticed this sequence repeats "C04D57B02B2B61C4", could that be a hint? It also has leading zeroes, does that point to any ...
-2
votes
1answer
12 views

Would this be a plausible authenticated encryption scheme using nested encryption?

[This is was the most promising out of an incrementally developed set of (mostly flawed, to some degree) schemes I posted here, but I was told I should post each one separately] Assume $E$ is a block ...
0
votes
0answers
10 views

Ring signatures in ECC

Are ring signatures possible with elliptic curves? If so how. The original paper by Rivest, Shamir, Tauman seems to require an invertible trapdoor function. But I've only seen algorithms for secret ...
0
votes
0answers
11 views

How many bits of entropy can I expect from /dev/urandom in iOS?

Apple's latest security documentation indicates that it now uses CTR_DRBG for generating pseudo-random numbers (previously Yarrow instead of CTR_DRBG), using "timing variations during boot" and ...
0
votes
0answers
15 views

Discrete log in Galois Extension Field

I was reading 'Pinocchio Coin' paper by Danezis et al. where they have said, "If we use the efficient pairing groups of Pinocchio, computing discrete logarithms in the exponent field $\mathbb{F}_p$ ...
0
votes
1answer
44 views

Finding public exponent e

I'm trying to create an algorithm to find the public exponent e given a plain (non-CRT) private key that doesn't include the public exponent, i.e. I've only got $n$ and $d$. A question has already ...
0
votes
1answer
21 views

How to calculate RSA CRT parameters from public key and private exponent

Given the public key (n, e) and private exponent (d), how to calculate CRT parameters (p, q, dP, dQ, and qInv) of this RSA key pair?
0
votes
2answers
30 views

Is it practical to use a stream cipher in a block cipher mode?

My idea is to use a stream cipher encrypting 16 bytes at a time as a primative block cipher in a mode of operation such as CBC mode. Is this practical or useful in any way?
-2
votes
0answers
21 views

Why don't we have hardware generate NON-pseudo, but REAL random numbers from meta-stable flip-flops?

Software pseudo-random numbers can always be cracked because they are based on a seed and therefore deterministic. Therefore, why depend on anything that's deterministic for security? The only real ...
0
votes
0answers
16 views

public key for encrypting and both private and group key for decrypting

A document is ecncrypted using publickey within a group(consists of many users with single public key and individual private key),then how to decrypt the document by using both public key and private ...
0
votes
0answers
48 views

Name of this attack?

I am studying Merkle tree signature. Let $\sigma=(s,Y_s,\sigma_{\text{OTS}},As)$ be a signature of certain document. Here $s$ is the index of leaf, $Y_s$ is the respectively OTS public key and $A_s$ ...
0
votes
1answer
28 views

Using ECB as encryption mode, but encrypted messages are unique

As I understand, ECB should not be used as encryption mode unless you are encrypting single blocks of data which are always unique and only are encrypted once. I have a collection of ids represented ...
0
votes
1answer
25 views

Are pseudorandom permutation really permutation in mathematical sense?

In security, and specifically Block Cipher (AES, DES, etc), when we talk about pseudo random permutations, is the term "permutation" refer to the same meaning as in discrete mathematics. That is, the ...
0
votes
0answers
25 views

Can you find the search space? [duplicate]

Let A is a random number and has 512 bits.we make B from A and B has 1024 bits.Process of B is following: C=f(A) that f is hash and C has 160 bits.Then C pass in a parallel manner 7 different hash ...
2
votes
1answer
35 views

Compacting a substitution cipher key

In a substitution cipher, I recieve 3 bits and than I return another 3 bits. The key of this cipher could be a matrix represented as: ...
-4
votes
1answer
50 views

Would this method allow fast authenticated encryption using only a single encryption and RNG operation per block?

The most promising of the 4 approaches described here (version 4) has been posted as a separate question. This post should be considered for archiving and historical purposes only. Disclaimer: the ...
0
votes
2answers
37 views

Would this method allow fast authenticated encryption using only a single encryption operation per block?

[This approach is flawed. A different speculative approach using an RNG instead of the cipher as a source of entropy was posted as a separate question] Assume $E$ is a block cipher, $C_0 = IV$ and ...
2
votes
2answers
174 views

Why does TLS do Authenticate-then-Encrypt instead of Encrypt-then-Authenticate?

Encrypt-then-Authenticate (EtA) seems to generally be considered the better option, compared to Authenticate-then-Encrypt (AtE) (see this Crypto.SE question, for example). The people writing the RFC ...
1
vote
1answer
15 views

Why do we truncate the hash when using DSA?

All the articles I read on the web about DSA keep telling me that the size of the hash needs to be truncated so that the bit length is equal to or lesser than the bit length of the prime number of the ...
0
votes
1answer
30 views

Executing encrypted code?

I want a code 'black box' that receives data inputs, processes those inputs, then sends out the outputs. I want the code to be encrypted, or somehow obfuscated. Is there any known way to do achieve ...
6
votes
1answer
118 views

RSA with probable primes

I am a bit of a newbie to RSA encryption, so please be patient. I understand that for a 4096 bit RSA, the numbers p and q should be prime. And to have the best security, the p and q should both be ...
-3
votes
1answer
21 views

Can you find the search space?

Let $A$ is a random number and has $512$ bits.we make $B$ from $A$ and $B$ has $1024$ bits.Process of $B$ is following: $C=f(A)$ that $f$ is hash and $C$ has $160$ bits.Then $C$ pass in a ...
-1
votes
0answers
42 views

Product of Sophie Germain Primes and safe primes [on hold]

I am testing the use of the product of 1024 bit safe primes as the RSA modulus, starting with Sophie Germain primes times their associated safe prime and the product of two sequential safe primes ...
1
vote
0answers
25 views

Hardening of random number generators

Boxcryptor uses various CSPRNGs and apparently hashes the output using PBKDF2 to derive the final key. Even though the choice of ...
0
votes
1answer
28 views

Does the One Time Pad rely on confusion or diffusion?

From what I could research, XORing a random key adds confusion. But I do not undertand the rationale for that classification. Shannon's confusion is supposed to obscure the relationship between the ...
-1
votes
0answers
15 views

Can Wireshark be used to trace SSL traffic to a server with DSA private key?

I tried to use wireshark to watch cipher negotiation between browser and a Tomcat server which uses DSA private key. and I got the following debug message: ...
2
votes
2answers
92 views
+100

How to prove that someone encrypted a specific (large) chunk of data

Alice encrypts her data with HER secret key. Then she sends the encrypted data to Bob who should encrypt it with HIS secret key. Caroline should then eventually get this double encrypted data. ...
-1
votes
0answers
20 views

A software for test and performance analysis of cryptographic algorithms

I'm new to cryptography and I have been assigned at college to do a comparison study between AES, DES, RC6 and SERPENT ciphers. Is there any graphical software than can help me analyze speed and ...
0
votes
1answer
31 views

Huffman encoding of hashes

I have a huge list of MD5 hashes, which takes up quite some space. I was wondering if I would acheive (some) compression, by encoding the characters (which are A-F 0-9), with huffman coding. I made a ...
0
votes
0answers
27 views

Curve41417 example

I have done an example, attached as image file, of the algorithm in Curve41417 by Daniel J. Bernstein et al. but my answer is not correct. I have checked it multiple times but couldn't find the ...
1
vote
1answer
31 views

HKDF entropy extraction

I collect entropy from the following sources: system_entropy = System provided crypto entropy stream (CryptGenRandom on Windows) user_entropy = User-provided entropy - in a form of a byte stream of ...
4
votes
1answer
39 views

possible MITM attack against servers that used to support weak DH?

from reading the TLS 1.1 RFC, it looks like it would be possible to break a previously recorded TLS <1.2, 512-bit DHE ServerKeyExchange and then send it (unmodified, with the original, valid ...
1
vote
1answer
28 views

Attacking CBC with predictable but encrypted IV

Let P be a secure block cipher, eg AES-128. Let's say a server has a CBC encryption oracle which uses an attacker-selected yet unique nonce to generate the IV for each message = P(key, nonce). The ...
7
votes
1answer
81 views

Logjam on Elliptic Curves?

I think we're all aware of the Logjam attack. From now on we know that re-using primes for DH is a bad idea. But we also say that elliptic curves are safe from the attack (relying on the NFS), ...
1
vote
1answer
23 views

Can a TLS client perform any DH regeneration?

I have only the barest understanding of cryptography, but I've been following the Logjam issue; some posts and articles (elsewhere) imply that a client can regenerate DH keys. Is Logjam solely a ...
0
votes
0answers
38 views

Factorization of a number obtained by a modular multiplication operation can reveal factors of the used operands?

Consider a number $r$ obtained by: $r=a \cdot b \mod n$ Can knowing the factorization of $r$ reveal some information (bits) of $a$ and $b$ ?
0
votes
1answer
22 views

Break El-Gamal Algorithm by knowing the value of the random k

In El-Gamal Algorithm, the public key is $(p, g, A)$, and the secret key is $(a)$, in order to encrypt some data, the sender generate a random $k$, where: $(C_1, C_2) = (m.A^{k} \pmod{p}, g^{k} ...
5
votes
1answer
43 views

Hard-core predicates: should the adversary be given $1^n$?

In most (all?) classical sources such as the book of Goldreich (2001), hard-core predicated are defined thus: A polynomial-time computable predicate $b : \{0,1\}^* \to \{0,1\}$ is a hard-core of a ...
2
votes
1answer
44 views

Hash length extension attack - SHA256 to 512 - impossible, correct?

Just want to be sure about something before I sign off on a method we're about to put into place. We have a secret, to which a user-defined key is appended. The user can see the SHA256 hash of the ...
4
votes
1answer
95 views

Logjam: “composite order subgroups” explained for TLS developers and system admins?

I have read the recent logjam paper Imperfect Forward Secrecy: How Diffie-Hellman Fails in Practice. On page 11 in the Recommendations section, they state: ...
1
vote
1answer
32 views

The difference in size between ECDSA output and hash size

So if I use secp256k1 for example, I've got my key size of 256 bit, and say I sign a SHA256 hash of a message, with size 256 bit, I get an output of size 512bit. Why is there a difference between the ...
-2
votes
0answers
33 views

I've been sent a code in binary, but I can't seem to figure out what to do with it [on hold]

My friend sent me a "puzzle" in binary, and said that there are multiple steps to solving the puzzle, all of them including decryption. I translated the binary into text and he said that was a good ...
0
votes
0answers
44 views

Finding Patterns in Encrypted Data

I am looking for an application (Windows) or code example that might help me find patterns in an encrypted file. I have a ciphertext for which I want to see when a key is repeated. I am not trying ...
0
votes
0answers
23 views

How to find the encryption method and password? [on hold]

I got an encrypted text, which was encrypted using a substitution cipher, and the corresponding plaintext. Now I want to find out what algorithm and password was used to encrypt it. How can I ...
1
vote
1answer
56 views

one-way deterministic hash for low entropy input?

My problem is the following: we have a low entropy data called ID. (personal id number of 10 decimal digits plus a sum, and it contains a date) We want to create a data (H) which is the same for the ...
1
vote
1answer
28 views

Decryption of Huffman code

I know that Huffman is not a encryption method, but I have a bit-stream that I know it's Huffman coded. However, the tree/table that maps the codes to real characters is not available. Surprisingly, ...
0
votes
0answers
21 views

Algorithms for Extracting Linear Equations in Algebraic Cryptanalysis [on hold]

There are some algorithms for solving linear equations in algebraic cryptanalysis but my question is that what the extracting algorithms are? Any help is appreciated. Regards.
0
votes
0answers
33 views

prepaid meters that rely on a disconnected system

i have some experience with cryptography in the banking sectors, mostly in block ciphers like DES 3DES etc. im interested in prepaid electricity meters as it is a number that is generated from a ...
0
votes
2answers
79 views

Is it possible to have identical public keys for different ciphers?

Is it possible (and is there any research I can read) to have 2 key pairs for different ciphers, for example RSA 1024 and some yet to be released EC (or other asymmetric cipher) than uses 1024 bit ...

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