Encryption is the process of transforming plaintext using a cipher into ciphertext to make it unreadable to anyone except those possessing the key. Decryption is the process of transforming that ciphertext back into plaintext, using the key.

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Encryption and HMAC in a PSKC file

This is the PSKC standard https://tools.ietf.org/rfc/rfc6030.txt In Section 6.1 6.1. Encryption Based on Pre-Shared Keys They have the following ...
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2answers
30 views

Embedded devices Authentication, Integrity and Confidentiality

Embedded devices send messages to the server. The server occasionally sends messages to individual devices(Reboot, upgrade firmware etc) After some research this is my ad-hoc solution: 1) Each ...
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4answers
181 views

Do Brute-Force Attacks and Cryptanalysis refute Kerckhoffs's principle?

According to Kerckhoffs's principle "A cryptosystem should be secure even if everything about the system, except the key, is public knowledge." Now I want to throw in a provoking formula of mine which ...
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0answers
20 views

Simple Encrypted Message, With Key Included [on hold]

Hi minds of Stack Exchange, today I present you the mysterious message that has been troubling my mind for the past one hour: From: 25 - 5()1 - 31 - 15(-)d Grade: 55 - 2(-) Class: 44 - ...
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2answers
67 views

Brute force against computational security

One-time pad is secure under brute force with respect to either of the definitions \begin{align} \Pr[M = m] &= \Pr[M = m | C = c]\\ \Pr[C = c | M = m_0] &= \Pr[C = c | M = m_1] \end{align} ...
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1answer
59 views

Encrypting decryption key

What's that property called when a scheme is secure even if you encrypt the decryption key? Some schemes have problems when your plaintext is the decryption key (or just the key if symmetric).
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0answers
27 views

Is AES-GCM length extension attack possible using authenticated decryption?

I am looking to encrypt a piece of data using AES-GCM with a full 16-byte GCM Tag and send it over the network using UDP. Is it safe to assume using the AEAD nature of AES-GCM that performing ...
-1
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0answers
29 views

Program implementation and flaws [on hold]

I had written an email encryption program in Java almost an year ago. I want to improve upon it and need your help in determining any obvious flaws in implementation and functionality. About program ...
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1answer
52 views

Does a cryptosystem provide unconditional security if and only if it provides perfect secrecy?

Is unconditional security and perfect secrecy one and the same thing, i.e a cryptosystem provides unconditional security if and only if it provides perfect secrecy ? I've wondered about the above and ...
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1answer
53 views

Can a cryptosystem be unconditional secure if the same key $k \in \mathcal K$ is used for more than one encryption?

Can a cryptosystem be unconditional secure if the same key $k \in \mathcal K$ is used for more than one encryption ? I know that the one-time-pad doesn't have perfect secrecy and doesn't provide ...
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0answers
16 views

Client Emulation - Sending hexdump to server and getting response [on hold]

So I used wireshark to retrieve a hexdump that has been encrypted with RSA. I need to figure out what the response to that would be when it comes back from the server. How I imagine it would work ...
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2answers
139 views

How can a cryptosystem be unconditional secure?

How can a cryptosystem be unconditional secure ? The definition of an unconditional secure cryptosystem states that the cryptosystem cannot be broken even with infinitely computational ressources ...
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1answer
68 views

Formal relationship between encryption and random number generators?

Cryptographically secure random number generators seem to have similar properties to symmetric encryption: initial seed is permuted to produce a random numbers (key and ciphertext) given the seed, ...
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0answers
35 views

vector space retrieval model [closed]

In tf-idf weighting scheme of vector space model, weight matrix is calculated as a product of term frequency(tf) and inverse domain frequency(idf). I need paillier dot product calculation here. Can ...
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0answers
49 views

how can I understand nonlinear coding for error detection

I want to understand how nonlinear coding can detect the errors in cryptography computing . actually I don't know what these code doing and what are the codewords in this system. now can any body ...
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1answer
52 views

Perfect secrecy of a crypto system

Suppose we have the following crypto system: $P = C = K = \{0, 1, . . . , n − 1\}$, $E_k(x) = (x + k) \bmod n$ and $D_k(y) = (y − k) \bmod n$. Prove that the crytosystem has perfect secrecy. Perfect ...
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5answers
424 views

Why are primes important for encryption

Why are primes so important? Why can't we just use a random number? My guess is that it's because finding a random prime require more computing power, than finding a random number. Can anybody confirm ...
4
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1answer
99 views

Dancing confusion with Daniel J. Bernstein's stream ciphers

I know of Salsa20 which won the ESTREAM competition. This is dated of 25 Dec 2007. There is also the ChaCha20 stream cipher (cr.yp.to/chacha.html). This claims to increase the amount of diffusion ...
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1answer
75 views

one time pad regarding

If I had two ciphertexts $$c_1 = m_1 \oplus y_1 \text{ and } c_2 = m_2 \oplus y_2$$ will it be possible to obtain $$z_1= (m_1 \lor m_2) \oplus y_1 \oplus y_2 \text{ and } z_2= (m_1 \land m_2) ...
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0answers
48 views

Encryption key input by a user [closed]

I was looking for some research papers where the security scheme is using 'user input' key method (but could not find). I mean, some approaches where user will be the one who will put keys for ...
2
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1answer
137 views

How to customize a standard encryption algorithm?

I want to modify and customize AES encryption algorithm and develop a variant of it. What factors should I consider so that it does not become weaker? What skill sets would be required to undertake ...
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0answers
31 views

electronic voting system [migrated]

Was looking at cryptocurrency and how, as a non techy, to get involved when I began thinking about the security of it being developed to undermine the stranglehold bankers have on economy and the ...
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2answers
157 views

What would be the best plain text Cryptography method without the use of a computer? [closed]

What would be the best Cryptography method without the use of a computer? This could be a list of the current options available, that could be used without the use of a computer ...
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46 views

Security considerations on using key derivation to create one-time keys for block ciphers

I'm planning to do some block encryption with AES and Blowfish (both with 256 Bit keys) chained. Master key generation: A 32 byte long persistent (over many years) master key is derived from a ...
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0answers
48 views

Asymmetric encryptions' computational complexity [duplicate]

I need to know the computational complexity of the public key encryption (e.g. Paillier), please. (i.e.Paillier in his paper mentions that the computational complexity of most of public key ...
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1answer
120 views

Secure double encryption using CPA and CCA

Do you mind if you give me any hints, links or ideas about how to improve the security of double regular encryption and decryption, by using CPA game and CCA game, it sounds interesting question, and ...
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1answer
89 views

My own encryption algorithm - if someone can brake [closed]

I wrote recently my own encryption algorithm. I want to test it so, since I know that here are a lot of professionals, I will write here some encrypted text and if someone is able to decrypt it please ...
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1answer
46 views

Oblivious transfer variation question

Now I am doing a variation of the oblivious transfer, I have to use 2 people, pebbles, and boxes. I need to find out if who has a larger number between Alice and Bob (variation of Yao's Millionaires' ...
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1answer
48 views

What cipher algorithm is this routine using? [closed]

I transfered a code routine from Java to Python: ...
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1answer
37 views

Repeating something encrypted and non-encrypted?

If one wants to keep the receiver's name non encrypted, but it also appears in the encrypted message - will it leak information? (other than the receiver's name, of course.) Let's assume a "bad" case ...
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1answer
100 views

Reversing a Psuedo Crytographic Hash [closed]

I'm trying to get a better understanding of cryptographic hashing. Take the example transformation function below, is it possible to reverse this formula to solve/isolate for message[i]? ...
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0answers
30 views

how can I change representation of point to Jacobian coordinates in Edward's Curve

I want to simulate this algorithm but I want to change it's output to Jacobian coordinates. what should I do ? In the other way how can we change extended homogeneous coordinates to Jacobian ...
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0answers
21 views

How to compare security parameters of different schemes (Sign-Encrypt, Encrypt-Sign, etc)? [duplicate]

How can one compare the security parameters (confidentiality, integrity, non repudiation, etc.) for different schemes (Sign-Encrypt, Encrypt-Sign, Sign-Encrypt-Sign, Encrypt-Sign-Encrypt)? Are there ...
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0answers
26 views

Encrypt algorithm [duplicate]

Is it possible to encrypt an algorithm? What I mean by this is have a remote/cloud computer execute a program that will process some data... And the remote computer would not be able to know anything ...
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0answers
39 views

Encryption using elliptic curves

What is currently the best way to actually encrypt a message using elliptic curves? I'm looking for an algorithm like ElGamal, but more efficient, since ElGamal outputs a tuple of two points for every ...
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1answer
140 views

Why there are limitations on using encryption with keys beyond certain length?

I am writing a java program to encrypt a message using 256-bit AES encryption, but I am getting illegal key size error, I have read that I have to use some JCE ...
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0answers
47 views

RSA OAEP: prevention of partial decryption of ciphertexts

I'm trying to understand RSA encryption (as a beginner in cryptography). go on this wiki page http://en.wikipedia.org/wiki/Optimal_asymmetric_encryption_padding scroll down to the 2 numbered points: ...
2
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1answer
67 views

what are multi-primes and how are they different from semiprimes?

I came to know of semiprimes recently. The simplest explanation of semiprimes is you take any two prime numbers and you multiply them, say 3*11 = 33 in which case 33 would be a semiprime. The numbers ...
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34 views

Real life RSA/El Gamal examples

Can someone direct me to examples of El Gamal and RSA that would be similar to real life (i.e. large primes). I wrote a code for encryption and decryption, but I wanted to test it against some larger ...
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0answers
45 views

Mifare Classic and crypto1 algorithm

Mifare's Crypto1 algorithm uses a 48-bit LFSR. What does the 48-bit LFSR do exactly ?
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59 views

Bilinear Map vs Inner Product [migrated]

What is the difference between a Bilinear Map and a Inner Product?
3
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2answers
137 views

Can a secret message be securely transmitted within a MAC tag?

A sender wants to transmit an ultra secret code $M$ which could be either 'go', 'stop' or 'wait'. This could be any selection of code words really and adopted for any use such as transmitting short ...
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1answer
61 views

What Java actually stores inside Keystore when generating Keys?

When we use Keytool to generate a Keystore to store Private/Public keys, what Java actually stores inside the Keystore file ? I ...
2
votes
1answer
100 views

To prove $r \cdot f_1 +f_2 \cdot (s+1)$ is secure

We define the polynomials $r, f_1,f_2,s \in R[x]$. Where $r$ is a random degree 1 polynomial and $s$ is a random polynomial such that: $degree(s)=degree(f_1)=degree(f_2)$, let $R$ be $\mathbb{Z}_p$ ...
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0answers
59 views

Modes of encryption for hard drives?

What are the currently recommended modes of encryption for large disks? Basic requirements would seem to be that you can update an encrypted sector independently of others, which rules out most ...
1
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1answer
112 views

Where have all the cypherpunks gone?

In 1992, cypherpunks was created as a mailing list for activists advocating for cryptography. Arguably, the cypherpunks mailing list was the foundation for the movement and the centre of it all. ...
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0answers
44 views

How many characters per block in an El Gamal ECC cryptosystem?

While I look for how many characters that can be encrypted using the The elliptic curve ElGamal cryptosystem. of each block found for these lines. But I can not understand Actually in our case we ...
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0answers
74 views

Interactive assumptions not falsifiable?

Can someone explain why an interactive assumption is not falsifiable? Maybe I'm misunderstanding what the statement means, but isn't even a non-interactive assumption interactive, but just with a zero ...
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0answers
94 views

How can I start the following crypto project?

(Cryptography: encrypting files before storage in the cloud): The project consists of a software implementation of a method to pre-process a file before storing it on a cloud storage server so that ...
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1answer
60 views

Rabin Cryptosystem Problem (variant)

My understanding of Rabin We have p and q which are distinct primes congruent to 3 mod 4. ...