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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Is python a secure programming language for cryptography?

I know Python is a powerful programming language but is it secure for cryptography? I mean is it possible to reverse engineer the program (written in python) and discover the algorithm of cryptography ...
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2answers
98 views

RSA signing security

I'm curious about the security of RSA signing with the same public private key pair when the same message is sent multiple times. It's my understanding that once you generate the hash of the message ...
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0answers
67 views

Exploration of Blum Micali Security By Seed Size

I'm new to cryptography and am most intrigued by mathematically based pseudo random number generators. With reference to the Blum Micali algorithm: $X_{i+1} = G^{X_i} \bmod P$ can security be ...
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0answers
212 views

Public key encryption and big files with NaCL

I am trying to encrypt big files using NaCL (actually PyNaCL) - see http://nacl.cr.yp.to/box.html After reading some docs, I came up with this prototype : Bob wants to send a big file to Sarah. They ...
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1answer
76 views

I have a keyword and cipher text but cannot decode it please help! [closed]

coded text: ij gj hnev xudmyx hn igim umif obaxidyw kxzq si the key is JULIET, but i cannot figure out how it is used. Any help would be awesome!
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2answers
166 views

What cryptanalysis is possible against two independent keystreams XORed against plaintext?

If a wise person was unsure about which commercial cryptography standards are truly secure from the fascist powers that be, it would seem the obvious option for companies and individuals is to now use ...
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0answers
71 views

How does bitmessage encryption work?

I have been reading around protocol specification and there is either too much technical detail or too bad articles on various sites. I need you to explain in simple words how encryption in ...
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0answers
71 views

How does multi platform encrypted cloud storage work?

I'm really interested in end-to-end encrypted cloud storage and couldn't find out how following scenario could work: A user of a cloud provider which provides zero-knowledge-authentication (like for ...
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0answers
67 views

RSA public key exponent generation confusion

Quote from Wiki: $e$ having a short bit-length and small Hamming weight results in more efficient encryption — most commonly $2^{16} + 1 = 65537$. However, much smaller values of $e$ (such as $3$) ...
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1answer
130 views

Montgomery Algorithm

I'm trying to undestand how it works and how to implement the algo described in this paper. The paper shows a methods to compute a modular multiplication where it is used multiplier with a resolution ...
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1answer
76 views

Unbreakable code and mathematical impossibility

Is an unbreakable code mathematically possible , considering a code with finite number of characters but has infinite combinations , using brute force is it not compulsory that the correct code be ...
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1answer
71 views

Using hash of plaintext as nonce in NaCl secretbox- bad idea?

I need a nonce to encrypt my stuff using NaCl secretbox. I will be transmitting the nonce along with the ciphertext, which I have been told is OK to do. It occurs to me that one could simply use the ...
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1answer
38 views

Many Time Attack [closed]

How i can XOR these two cipher texts encrypted by using same key First ...
0
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1answer
94 views

How secure is file header encryption for large files?

I'm having trouble location information about whether or not encrypting a file's header is good enough. The files in question are media files that range in size from 500mb to 4GB. If I had no ...
2
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1answer
117 views

Deduplication: Encrypting the SHA-256 hash of a file chunk

I'm designing a data storage system that should be both able to deduplicate data that share the same encryption key, and be reasonably secure. I know that this kind of encryption quality can be ...
10
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3answers
2k views

In what way is XXTEA really vulnerable?

I'm looking at using the XXTEA algorithm to encrypt a small amount of data (say, less than 32KB) in the context of a software licensing algorithm. That is, we wish to make it difficult (not ...
4
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2answers
148 views

Share encrypted files without giving master key

Imagine I have four files I want to encrypt. I have master key, and from that master key I derive four keys, one for each file: ...
0
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1answer
46 views

Public key encryption [duplicate]

I am not getting whole idea behind Public Key Encryption technique. As according to fact, public key encryption method uses two keys a public key known to everyone private key known only to recipient ...
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0answers
127 views

fuzzy commitment implemenation to make secure biometric template

I want implement some ideas from an article that is about making secure biometric templates using fuzzy commitment and fuzzy vault. I need to implement just the fuzzy commitment (fuzzy commitment is a ...
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1answer
49 views

Interested in learning cryptography [duplicate]

I'm interested in learning cryptography outside the university(studying civil engineering). I was always interested in computer sciences and programing and in mathematics. I always try to program ...
3
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2answers
93 views

Encryption for a short packet size

I have an 8051 microcontroller with a radio that can send packets with up to 32 bytes and I want to have the messages encrypted. It is a sensor network so I really only want to send one packet per ...
8
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3answers
2k views

How will Cryptography be changed by Quantum Computing?

I realise this isn't a 'yes or no' question, and I apologise for asking something that could be seen as a discussion thread, but I had to ask. I'm currently doing an EPQ in CS (specifically how QC ...
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4answers
192 views

what is it called when encrypt('a') + encrypt('a') == encrypt('aa')?

So normally if you do encrypt('a') twice in a row you'll get the same result. But sometimes (as is the case in SSH) this is not desirable. You want encrypt('a') + encrypt('a') == encrypt('aa'). What ...
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1answer
99 views

Transforming a key into a seed with the most entropy

I'm making a very simple encrypter in C# which is basically a Stream cipher. The user enters a key(password), converted to a seed for a pseudo-random generator, and the pseudo-random generator ...
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1answer
58 views

If I know the salt, can I decrypt the commitment?

Say, I salt my key(K) with y. So, my new Key is K' = Salt(K+y). Now, Alice sends commitment = E[K',M] to Bob. Bob knows the salt(y), but not K nor K'. Can Bob decrypt the message?
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2answers
634 views

How much extra information is in an RSA public key?

I'm trying to calculate the size of an RSA public key in Ruby. I've retrieved the key in PEM format, and once I've decoded the base64 part from the PEM format, I get the size in bytes. What I find is ...
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1answer
59 views

Is it possible to decrypt this message with partially known data? [closed]

The following highlighted text must contains "547a5e0e008be33730158d63ce844e67" data. I don't know about encryption method and key. Is it possible to decrypt it? Or just give me some idea about ...
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1answer
145 views

can anyone give the java code to encrypt files using paillier [closed]

I want to implement encryption on personal files using paillier encryption. Is it possible to encrypt files using this encryption..
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1answer
92 views

Possible to know who is the owner of a message encrypted with RSA public key

Given the scenario in which I want to send 10 messages either to Stalio or Olio. I encrypt these messages with their respective public keys using textbook RSA, before sending the messages to their ...
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2answers
583 views

Advanced Access Content System (AACS) and Subset Difference techniques for Broadcast Encryption

I'm trying to get a grasp on AACS and Subset Difference for a project I'm working on and am having a hard time coming up with a technically valid layman explanation, let alone implementation. Is it ...
2
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1answer
97 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 ...
8
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3answers
2k views

Why shouldn't I use ECB encryption?

I'm using Java to generate encrypted strings, and I get this warning at build time: ECB encryption mode should not be used So I'm wondering why I shouldn't use ECB and what I can use instead?
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1answer
114 views

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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1answer
86 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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5answers
586 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 ...
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4answers
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Do Brute-Force Attacks and Cryptanalysis refute Kerckhoffs's principle? [closed]

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 ...
2
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1answer
67 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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1answer
77 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 ...
2
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1answer
56 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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2answers
468 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 ...
3
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1answer
91 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, ...
2
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1answer
103 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 $\mathbb{Z}_p$ ...
1
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1answer
83 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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1answer
71 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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2answers
199 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 ...
5
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1answer
179 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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How represent message in Menezes–Vanstone elliptic curve cryptography

I ask about represent message in Menezes–Vanstone elliptic curve cryptography I now encrypt function as follow $C_1 = (M_1 * K_1) mod\ P$ $C_2=(M2 * k_2) mod\ P$ My question is about how much the ...
2
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1answer
177 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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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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1answer
192 views

rsa public and private keys

I have a question about RSA key generation. This is a simple RSA algorithm: Choose p = 3 and q = 11 Compute n = p * q = 3 * 11 = 33 Compute ?(n) = (p - 1) * (q - 1) = 2 * 10 = 20 Choose e such that ...