1
vote
1answer
27 views

Can I use the Sequence Number as the (implicit) IV in AES-GCM IPsec?

The RFC https://tools.ietf.org/html/rfc4106#page-5 states that, under AES-GCM IPsec, each packet is expanded by 8 bytes for the IV and up to 16 bytes for the ICV. Why? Since we already have a ...
0
votes
0answers
21 views

Diffie-Hellman combined with DSA/RSA

we have learned Diffie-Hellman, RSA and DSA (Digital Signature Algorithm) in university. Because DH is vulnerable of Man-in-the-Middle we had the task to program the DH combined with RSA to protect ...
-1
votes
0answers
55 views

NSA Suite B revoked [closed]

NSA Suite B was formerly documented in CNSSP-15 "National Information Assurance Policy on the Use of Public Standards for the Secure Sharing of Information Among National Security Systems". NSA has ...
3
votes
1answer
101 views

Change initial hash value of SHA512/t

Fips 180-4 defines under 5.3.6 how to calculate initial hash values for SHA512/t for a given value t. Can someone explain me how the t actually affects the outcome of the procedure (which, as far as I ...
4
votes
1answer
662 views

What does this notation stand for when describing a code?

This code has appeared in some online course material. I understand the $(5, 4, 3)$ refers to (length, num codewords, distance) but no explanation of the $Z_2^5$ notation is given: One $(5,4,3)$ ...
45
votes
5answers
32k views

Can you help me understand what a cryptographic “salt” is?

I'm a beginner to cryptography and looking to understand in very simple terms what a cryptographic "salt" is, when I might need to use it, and why I should or should not use it. Can anyone offer me a ...
0
votes
1answer
31 views

factorization of an integer $N$ that is in special format

Suppose $p_0$ and $q_0$ are known prime numbers and define $p_i$ and $q_i$ as follows: $$p_{i+1} = next\_prime(p_i^2 + q_i^2), \qquad i \ge 0$$ and $$q_{i+1} = next\_prime(2p_iq_i), \qquad i \ge 0$$ ...
1
vote
0answers
31 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
77 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
24 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 ...
0
votes
1answer
65 views

Key Hierarchy and key Encryption

If i have two 56-bit DES keys, and I use these two key to encrypt a 256-bit AES key. Like this $K_{AT}$ encrypts $K_{BT}$ and $K_{BT}$ encrypts $K$ What is the effective security of key $K$? Is it $...
16
votes
2answers
7k views

How does order-preserving encryption work?

Order-preserving encryption (OPE) is, apparently, a method of encrypting data so that it's possible to make efficient inequality comparisons on the encrypted items without decrypting them. I've been ...
3
votes
0answers
137 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 ...
48
votes
6answers
35k views

How can I generate large prime numbers for RSA?

What is the currently industry-standard algorithm used to generate large prime numbers to be used in RSA encryption? I'm aware that I can find any number of articles on the Internet that explain how ...
0
votes
1answer
26 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 ...
5
votes
5answers
231 views

Is it better to encrypt before compression or vice versa?

Is it better to encrypt a plain text file before compression, or vice versa?
4
votes
0answers
74 views

Security of Fernet Construction (wrt non self delimiting tokens and HMAC short key size)

Fernet is a described as a "high level symmetric encryption recipe" (source) that seems to be the default high level encryption scheme in the cryptography python ...
-2
votes
0answers
15 views

How does the input of (0..11) (512 bit) impact on the SHA-1 algorithm [duplicate]

If my H0(A0=B0=...=000hex) I think i wouldnt´t change anything and and my output for Round 1 would be K1 = 5A827999(hex)
0
votes
0answers
26 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 ...
4
votes
1answer
60 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 ...
5
votes
1answer
65 views

Difference between hierarchical and multi level secret sharing

In this paper, the definitions are simply as follows. Multi-Level secret sharing: Higher level participants can help lower participants to get the secret. Compartmented secret sharing: Each level ...
3
votes
1answer
115 views

Why should $a,b < N$ for Montgomery Reduction?

In Montgomery reduction, when calculating $a \times b \mod N$, it is required that $a \lt N$ and $b \lt N$. I think $0 \le T \lt N \times R$ is enough for the Montgomery Reduction. Rationale: Let $a'...
2
votes
1answer
119 views

Using e-ID Number for Encryption and Digital Signing

I want to use e-ID number for performing Encryption/Decryption and Digital Signing - and in order to do so, I've opted a PGP-oriented approach which goes a bit like this. Generating PGP key-pair ...
3
votes
0answers
40 views

A few questions about CRC basics [migrated]

I am an electronic engineer and have not found it important to consider CRC from a purely mathematical perspective. However, I have the following questions: Why do we add n zeros to the message when ...
10
votes
1answer
437 views

Compact digital signature for noisy data

The question asks for a signature scheme, with a public verification procedure, that is tolerant to minor alterations of the signed data during its transmission [possibly in analog form over some ...
-1
votes
0answers
18 views

C# to PHP partially decoded string [closed]

Hello I am trying to send data from c# application to my webserver. And I got like 99% of data decrypted right now the use of URI.encode helped me a lot to increase sucessfull decryption by many %. ...
11
votes
10answers
3k views

Are there any advantages in using proprietary encryption?

Proprietary software generally relies on the fact that in keeping the encryption algorithm private, it gets an extra layer of security implying "Security through Obscurity." Obviously this phrase has ...
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
119 views

Quantum vs. regular computing time to break ECC?

How long exactly would it take for a regular computer to crack an elliptic curve public/private key via bruteforce, vs. a quantum computer using Shor's algorithm with a couple thousand qubits? Can ...
5
votes
1answer
258 views

How long does it take to decrypt an RSA/ECB encrypted message?

I am working on assignment where I have specific scenarios and I am little bit struggling with this one. Alice sends and email to Bob.For this e-mail, she uses the following method of encryption: ...
1
vote
2answers
86 views

Appropriate scrypt parameters when generating an scrypt hash

What values for CPU, memory and parallel difficulty should be used when generating an scrypt hash? i.e. ...
2
votes
1answer
39 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?
2
votes
1answer
25 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?
7
votes
2answers
364 views

Can Shor's algorithm compromise RSA when both the public and private key are secret?

If RSA is to create a public private key pair and encryption is performed on plain test P to create cipher text C, given P and C could Shor's algorithm be used to find either of the public and private ...
7
votes
3answers
171 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 ...
1
vote
2answers
55 views

AES encryption for pairwise identifiers

I'd like to map a random ID of 16 bytes (sourceID) to another random ID of 16 bytes (targetID). The operation should: only be reversible by me be deterministic There are about 1 million source ...
3
votes
2answers
3k views

How to calculate the maximum output size for data encrypted with a RSA Private Key?

I have an an encryption algorithm I am working with that looks like this: prv_key_enc(sha1_hash(data)) Where, the RSA parameters are: RSA/ECB/PKCS1Padding 1024 ...
3
votes
1answer
48 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 +...
2
votes
2answers
57 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(...
1
vote
0answers
62 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 \...
0
votes
1answer
44 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 &...
2
votes
0answers
22 views

LENGTH Parameter in the EEA2 AES-128 of LTE

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
39 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 ...
2
votes
2answers
477 views

What is the motivation behind Key-policy Attribute-based Encryption?

What is Attribute Based Encryption? has a nice explanation what both forms (Ciphertext-policy Attribute-based Encryption and Key-policy Attribute-based Encryption) are. My question is: what is the ...
-1
votes
0answers
48 views

Computational Cost : Scalar Multiplication vs exponentiation in elliptic curve

$Pub=\gamma P$ and $Pub=P^{\gamma}$ where $P \in G_{1}$ and $\gamma \in Z_{p}$ Which one has less computational cost?
3
votes
1answer
59 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,...
2
votes
2answers
85 views

Fixed primes in discrete logarithm

The discrete logarithm problem is to find $z$ when the inputs are $g,h,p$ where $g^z\bmod p$. Supposing if you fix $p$ then does the problem become any easier to attacks and is there a $(\log p)^c$ ...
3
votes
1answer
81 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 ...
3
votes
2answers
55 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 ...

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