1
vote
0answers
33 views

Are public key and private key exchangeable? [duplicate]

If I get a key pair from RSA algorithm, can I make Private-Key public, and keep Public-Key secret without breaking the security of encryption and signature?
5
votes
1answer
99 views

Nonce for AES GCM to prevent replay attacks

I am wanting to encrypt a message with a pre shared key that uses AES GCM from the OpenSSL library to do so. I generate my key for the AES crypto via hashing my pre shared key with a salt using the <...
0
votes
0answers
31 views

What is the best approaches to find the type of a Cipher / Encryption? [duplicate]

There are many known and unknown encoding and encryption types / algorithms. When the algorithm is known, then at least it gives some direction or approach on what to do next to obtain the plaintext ...
3
votes
0answers
149 views

Inverting a candidate one way function

Let $w = a_0 \cdot a_1 \cdots a_{n-1} $ be a word from $ \{0,1\}^n $, $|w| = n$ Let $m = \sum_{i=0}^{n-1}{ a_i \cdot 2 ^ {n-1-i} } $ be the corresponding binary number constructed from the word. Let ...
5
votes
1answer
71 views

Are there any high level memory-hard PBKDF constructions?

The PBKDF2 construction from PKCS #5 v2 has the convenient feature that it can be implemented using only standard interchangeable cryptographic primitives. Specifically, it only requires the ...
0
votes
0answers
27 views

Error Detection/Correction Code-Then-Encrypt

I've just studied about the error correction schemes and encryption. First rule when using EDC/ECC is to first encrypt and then calculate them, and the major motivation we were told is that "EDC/ECC ...
0
votes
1answer
32 views

Secure Cipher Suites supported by JDK versions [closed]

I'm a n00b to cryptography. I've been searching through oracle's java docs, ssl labs, googling and more googling attempting to find an up to date list of cipher suites considered secure for the ...
4
votes
1answer
69 views

What is the recommended number of iterations for Argon2?

I've recompiled my operating system ("LionBSD" based on FreeBSD) to use Argon2i as the default password hashing algorithm in crypt/libcrypt. I'm wondering what the recommended number of iterations ...
0
votes
0answers
15 views

How much bandwidth is used in a typical IKE/ISAKMP initialization?

How much bandwidth is used in a typical IKE/ISAKMP initialization? How many UDP packets are sent in each direction, and what is their typical size? I'm referring to initialization of IPsec via IKE/...
2
votes
1answer
43 views

what kind of custom header add to encrypted file to identify my encryption,consider safe and reliable.like pseudo format extension or file size

I want to add some custom header to encrypted file to identify my encryption,consider safe and reliable.like pseudo format extension or file size.Is there any algorithm or tool to make it?
4
votes
3answers
253 views

After a diffie hellman key exchange, what is the common secret used for?

What is the common secret that is established used for? What types of interactions are now possible?
2
votes
1answer
26 views

Older key as PGP subkey?

Currently I have a 2048-bit PGP key. Suppose I create a new 4096-bit key. Can I add that old key as a subkey of this new one?
3
votes
1answer
53 views

Is a hash function used to expand the key after ECC shared secret is complete?

I am trying not to solicit opinions, but I have not been able to find a reference to the question at hand. I have designed an ECC engine in silicon that handles any curve in the form of $y^2 = [ax^3 +...
1
vote
1answer
63 views

How was the AES MixColumns matrix constructed?

How was the constant matrix in AES MixColumns constructed? \begin{bmatrix} 02 & 03 & 01 & 01 \\ 01 & 02 & 03 & 01 \\ 01 & 01 & 02 & 03 \\ 03 & 01 & 01 &...
3
votes
1answer
50 views

What is the LENGTH parameter in EEA2?

In the EEA2 option for encryption in LTE the AES-128 algorithm is mechanized. There, the nonce used in the CTR Mode is a 128-bit value. The first 64-bits are covered by a COUNTER, a BEARER, a ...
0
votes
1answer
41 views

Hash Function representation in identity-based encryption

Some describe as $H:F_{q}\times G_{2}\rightarrow \{0,1\}^{n}$.Some describe as $H:\{0,1\}^{*}\times\{0,1\}^{*}\rightarrow F_{q}$. What is the meaning of product function? what kind of operation does ...
1
vote
0answers
66 views

Homomorphic encryption over finite fields

I'm curious on the following question: let $\mathbb{F}_{2^n}$ be a finite field which is an extension of $\mathbb{F}_2$ with order of $n$, is there an encoding scheme $e:=\mathbb{F}_{2^n}\rightarrow \...
3
votes
1answer
84 views

Why does 3DES need private key to decrypt?

I create two files, my.cer and my.pem ( include certificate and private key), I encrypt a file with my.cer, I use openssl smime -encrypt command. When decrypting data, it needs my.pem. I think 3DES ...
7
votes
0answers
253 views

culling equivalent Enigma keys for short messages [closed]

The following for-loop iterates over all possible keys for an M3 Enigma for three selected rotors: ...
7
votes
3answers
187 views

Encryption-then-encode or encode-then-encryption?

I have this question in which I m struggling. I have read in many sites about encrypt-then-mac etc. If the confidentiality for transmission is needed, discuss the feature for the order of encryption ...
3
votes
1answer
64 views

What would currently make the strongest https connection?

when you look at the encryption websites use you will see that there is alot of diversity, some use 256 bit keys some do not, some use DHE-RSA some ECDHE some use sha 256 some sha1, but my question is,...
3
votes
1answer
62 views

Does encryption of data/information take place in peer to peer networks like Gnutella, Bittorrent?

Do peer to peer networks like Gnutella, Bittorrent have any encryption system to secure the users privacy or encrypt the file/data being shared? Elaborate please.
-3
votes
1answer
65 views

bruteforce on aes 256 cbc mode

i have a series of encrypted text , they encrypted by aes 256 bit cbc mode for every encrypted text there is an iv that i have them also and i know its algorithm is aes 256 bit cbc mode i can ...
2
votes
1answer
62 views

Is PKCS7 a signature format or a certificate format?

I always though PKCS7 was a signature format. However, on the net I find several references to PKCS7 being a certificate format - for example, this talks about PKCS7 certificate: Extract raw ...
3
votes
2answers
61 views

Output of a Linear Shift Register given Plaintext and intial state

Given an initial state $S_0 = (0101)$ and plaintext $P = 1010101011$ I need to find the ciphertext. The method to solve this was not taught in my coursework, and the information I have found online ...
1
vote
1answer
31 views

Some terms related to secret sharing: Optimality, What does it mean?

In any secret sharing scheme we have to develop step by step. After constructing such scheme we need to reduce share size. Why? e.g. Robust secret sharing scheme is modified Shamir secret sharing ...
2
votes
0answers
50 views

Is the ring learning with errors problem still hard if the errors are drawn from some subspace?

Let $R=\mathbb{Z}_p[x]/x^n+1$ be the ring used in normal RLWE, which is linear space over $\mathbb{Z}_p$ with dimension of $n$, let $S$ be a linear subspace of $R$ which described by linear ...
6
votes
0answers
58 views

Name of an archaic type of RSA padding (0BBBBBBB…)

In some legacy code, I encountered RSA signature padding in the following format (hexadecimal): 0B BB BB BB BB BB BB ... BB BB <hash> Is there a name for ...
2
votes
1answer
76 views

Why is Diffie-Hellman used instead of just RSA in key-exchange (TLS, IKE)?

Why should a key exchange protocol (such as in TLS or IKE) use Diffie Hellman? Why not just use RSA? For example: Alice picks a random session key, signs it, encrypts it with Bob's public key, and ...
1
vote
0answers
50 views

How can I obtain the raw decimal value of an RSA key's modulus?

So maybe I'm thinking about this too hard, or maybe I'm missing a piece of information. We'll use Google for this example. Say I wanted to obtain the modulus of Google's current public key. Well I ...
8
votes
3answers
653 views

Advantages/disadvantages of using symmetric encryption function as hash function?

Next to the traditional MD5 and SHA-1, other hashing algorithms exist based on symmetric encryption algorithms. An example is the Matyas–Meyer–Oseas construction. What are the advantages/...
4
votes
2answers
51 views

Why is synthetic IV (SIV) mode considered deterministic authenticated encryption (DAE)?

I was just going over my (old) notes from Coursera's Cryptography I course, and I was puzzled by the description of SIV as providing deterministic authenticated encryption (DAE). The general SIV ...
3
votes
1answer
66 views

identifying presence of encryption of zero in additive homomorphic encryption

Lets say the server has corpus of ciphertext contains $enc(a),enc(b),enc(c), \dotsc enc(x)$. The encryption function is an additive homomorphic scheme (like Paillier). The server knows only the public ...
2
votes
2answers
97 views

Calculating Polynomial Inverse with extended euclid in java

I'm trying to understand the NTRU-PKCS and therefor I wanted to code a naive Version of it. Now my Problem: I tried to calculate the inverse of a Polynomial with an extended Version of euclids ...
3
votes
1answer
71 views

Using Pollard's lambda in a key-recovery attack on DH

I've become interested in writing an exploit for the OpenSSL vulnerability here (CVE-2016-0701). Running through the bullets describing the attack, I can follow up to the last bullet point. Reviewing ...
1
vote
0answers
32 views

What is the right tool to MPC linear equations system

Given two parties who have private inputes Player 1 - $X_1,...X_n$ Player 2 - $Y_1,...Y_n$ We want to compute a solution to a linear system equation: $f_1(X_1,...X_n,...Y_1,...Y_n) +h_1(X_1,......
5
votes
2answers
131 views

Zero-knowledge proof system which is not proof of knowledge?

I have learned that a zero-knowledge (ZK) proof system can be constructed by making use of the three-color problem. In this particular case, the proof system also happens to be proof of knowledge (POK)...
0
votes
1answer
25 views

linear cryptanalysis: how are the subkey bits removed from the linear approximation?

I'm currently reading the tutorial on linear/differential crypta here: https://www.engr.mun.ca/~howard/PAPERS/ldc_tutorial.pdf End of page 14/Beginning of page 15: all the bits from the subkeys are ...
2
votes
1answer
62 views

How to prove a lemma that is based on phi-hiding assumption?

Assume that the $\phi$-hiding assumption is true, i.e. that for a composite number $m$, a PPT adversary A cannot distinguish between a prime $p_0$ that divides $\phi(m)$ and another prime $p_1$ that ...
2
votes
1answer
35 views

How to select a good scale for letter frequency in a text?

I needed to use a scale in a code to determine which sentence in a file has been encrypted by a single-character key. The scale that i currently used is: +2 for every occurrence of a vowel or a ...
2
votes
1answer
92 views

Is this a proper key-exchange implementation?

I've been trying to implement Diffie Hellman key exchange so far from my own understandings (I know I could just stick with SSL/TLS, but I want to understand it in depth more), so I created this basic ...
1
vote
3answers
68 views

Is PGP's way of maintaining email security optimal? [duplicate]

I read a book called "computer networking: A top-down approach". It talked about how PGP creates an email message between Alice and Bob to maintain confidentiality, integrity, and authenticity. Let me ...
2
votes
1answer
101 views

Reversing a known encryption algorithm (4-byte repeating key XOR)

I've been practicing for an upcoming CTF competition, and I've finally reached the cryptography stage. I'm a complete newbie in this field (my knowledge is essentially that bcrypt is awesome and md5 ...
1
vote
1answer
36 views

How can I determine key length for message encrypted by many-time-pad?

For message $ m $ and key $ k $ I get encrypted message $ c $ ($ m \oplus k = c $) where $ length(k) < length(m) $. Additionally I know that message $ m $ is English text. Instead of using pure ...
2
votes
2answers
61 views

Security (CPA?,CCA?) in Authenticated identity-based encryption

When I read authenticated identity-based encryption by Ben Lynn, encryption works to send data from user A to user B where: $$a=e(d_{A},B)$$ $$s=H_{3}(Msg,K)$$ $$C=<s,\gamma \oplus H_{2}(a,s),H_{4(...
0
votes
0answers
46 views

How to encrypt huge data using RSA? [duplicate]

Is there any way to encrypt the huge amount of data using RSA? I was supposed it is possible but when I read some articles what I saw is that, this is bad practice or they say can only encrypt bit ...
1
vote
1answer
30 views

Which one is correct probability formula for the same master secret value in identity-based encryption

Assume two servers $(n=2)$ use the same domain curve parameters and same hash function $H:\{0,1\}^{*} \rightarrow G_{1}$ . Then the hash value for the same identity falls in same result and let it be ...
2
votes
0answers
25 views

Why SSH does not use a certificate authority in the same way as SSL [closed]

SSL requires the use of a trusted third party -- the certificate authority to verify a public key presented by a server to a client. SSH on the other hand relies on the client having the server's ...
3
votes
1answer
72 views

How to verify a sever's ECDSA fingerprint during SSH

I have read somewhere that Servers which have SSH access for users in the public can have their public key posted publicly (e.g., on a website), so that people who access such a server using SSH can ...
0
votes
1answer
59 views

Using Shor's algorithm to solve the discrete logarithm problem

I have read about Shor's algorithm and my understanding is that it can be used to factor large numbers efficiently. Can Shor's algorithm, though, be used to solve this problem: Find the number $e$ ...

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