Questions tagged [encryption]
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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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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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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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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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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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 ...
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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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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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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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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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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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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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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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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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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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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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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 system/electronic ...
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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 ...
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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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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 ...
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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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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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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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how to calculate non linearity of AES S-box?
S-box has to satisfy different design criteria. How to calculate non-linearity , propagation criteria for an AES S-box?
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What cipher algorithm is this routine using? [closed]
I transfered a code routine from Java to Python:
...
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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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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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SHA1 - SSL/TLS Cipher Suite [duplicate]
SHA-1 is on the way to deprecation, in particular for digital certification (x509). But I can't find ressources about SHA-1 deprecation from SSL/TLS Cipher Suites.
Is it implicit, as deprecation ...
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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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Encryption algorithm designed to be easy to decrypt by machine but impractical to decrypt by hand
I am looking for - or considering the design of a new - encryption algorithm that does not use variable keys, such that it is easy for a computer to encrypt and decrypt any message regardless of its ...
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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: "...
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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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Large file validation on an embedded system through hash and encryption
As a preface, I have to say that I am a noob in this area. Having said that, I will ask the question.
I have a situation where I need to validate and protect against tampering a handful of large ...
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For calculating the index of coincidence for each sequence
I was learning about the finding the key length reading the following web site...
http://practicalcryptography.com/cryptanalysis/stochastic-searching/cryptanalysis-vigenere-cipher/
and I really don't ...
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How to perform frequency analysis of a substitution cipher using a Base64 alphabet
Let's imagine a cipher that works like the following:
Plaintext is encoded to Base64.
The characters in the encoded plaintext are substituted with a randomly shuffled character set(A-z, 0-9, -, _, =)....
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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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plaintext distribution ,perfect secrecy cryptosystem
I have been trying to solve the next problem:
let pi be a perfect secrecy cryptosystem with specific plaintext probability distribution.
How to prove pi will have perfect secrecy for all other ...
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How many of primitive point on the elliptic curve?
In elliptic curves for cryptography, I know $nG=O$, where $G$ is a base point represented by $G=(x_g,y_g)\ on\ E(F_P)$, where $n$ is Order of point $G$.
For example, $P(0,6)$ is a primitive point on ...
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Key derivation for AES-Encryption key and HMAC
Okay so I have two options for how I would derive two keys for AES encryption and HMAC they are as follows:
Run BCrypt on a users passphrase and then use the bouncy castle implementation of HKDF in ...
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What is primary security in ECC?
I read the following paragraph in a book about Elliptic Curve Cryptography, but didn't understand it:
The primary security in ECC is the parameter $n$; where $n$ is Order of point $G$, that is $n$ ...
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Best practices (if any) to add metadata to encrypted files
I am encrypting files using AES/CBC/PKCSPadding, with 256 bits long keys. So far the first 16 bytes of each encrypted file are the IV.
I would like to store some more information regarding the ...
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RSA-KEM construction
"Create a random key for CCPA2 scheme, encrypt m, send it along with a
PK encryption of the symmetric key. "
Say in the process, the KDF is HMAC, then:
get a random key (128-bit)
C1 = encrypt the ...
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Can hashing become encrypting?
hashing some data and encrypting data share some similar attributes. Surely this is why "Difference between encrypting something and hashing something" has been asked.
The point of this ...
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Using bcrypt derived keys for encryption?
Sorry for this ignorant question but I am currently weighing up the advantages and disadvantages of BCrypt over PBKDF2 and from what I have read BCrypt is considered more secure but from what I have ...
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Why has SSL v3 not yet been upgraded to a higher version with stronger principles, what are the dependencies and issues to do so?
SSLv3 is almost 18 years old; why has it not been updated to a more advanced version with stronger rules and structure. What have been the issues and dependencies in doing so till now???
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Can RSA signing be implemented on top of RSA encryption/decryption?
I need to use RSA-SHA256 signing. Unfortunately not all Microsoft CryptoAPI providers support that. It's possible that I might get a handle to a CryptoAPI provider that can just encrypt/decrypt with ...
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Opinion on my idea for storing credit cards securely
I've been thinking of ways to store credit cards securely, I thought of this:
Take the users credit card info
Put the card info in a standard format
"Full Name/Card Num/Security Num/Expiry Date"
...
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Determining message given cipher-text and public key [duplicate]
Consider the following scenario:
Suppose A and B have set up their RSA public keys, namely $(e_a, n)$
and $(e_b, n)$, where the n-value is the same. Also, it happens that
the $\gcd (e_a, e_b) = ...
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Brute Force AES Calculations
I have an encryption service in which the user decides the length and the type of key, so I would like to build a tool that educates the user on the brute force times for the key they created if using ...