Encryption is the process of transforming plaintext using a cipher to make it unreadable to anyone except those possessing the key.
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1answer
22 views
What is U2FsdGVkX1?
Using CryptoJS 3.1 I noticed that using 3Des, the encrypted message always start with
U2FsdGVkX1
Why is the first part of the encryption always the same?
What information does this hold and ...
0
votes
0answers
24 views
Reverse engineering from known ID inputs and 19/20-digits outputs
I am currently having few samples of a hash encryption function as per following
ID Hash
542591 6896202108404922949
3210 7693203936755907764
2455 14877541378540063734
2275 ...
1
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1answer
91 views
How do I decrypt ciphertext with this cipher?
I have an encryption function
$$E(p) = (ap + b) \mod{26}$$
where the parameters are $a=7$, $b = 10$, and $p$ is the plaintext letter.
I was asked to decrypt the ciphertext
...
1
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1answer
98 views
Security of authenticated encryption modes gcm & ccm
I have two questions for Clarification for AE mode choice criteria
GCM : it appears to be actually the most popular and widely used AE mode of operation. however it is also well-known to be highly ...
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3answers
66 views
OpenSSL AES 256-bit Key Management
I am using C and OpenSSL to encrypt files. After experimenting with the OpenSSL command line utility, it makes you enter a passphrase that can be any length, but uses that to create a 256-bit key.
...
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1answer
47 views
How to choose the appropriate public (i, m) and private (j, m) keys?
I studied some encryption and decryption and I have found some very interesting problem to solve on the internet. I hope I am writing to right site - there are so many in StackExchange otherwise I ...
3
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3answers
60 views
What are some good references for the implementation weaknesses in RSA
I'm pretty sure I understand textbook RSA.
Choose p and q, large primes, and compute n=pq.
Choose e such that $gcd(\phi(n),e)=1.$
Publish n and e.
Compute d such that $de=1$ (mod $\phi(n)$).
To ...
2
votes
1answer
82 views
Can you identify the public key used to encrypt something?
If I encrypt a string with a public key, does the encrypted ciphertext reveal the public key I used to encrypt it? Basically, I don't want anyone to know who the ciphertext is addressed to.
I'm ...
2
votes
2answers
64 views
Is it possible to anonymize web traffic so that the IP Address cannot be determined while still being able to determine distinct IPs?
I'd like to find a way to anonymize IP addresses in web logs to ensure user privacy given the following requirements:
If given an IP address, there is no way to look up which requests came from the ...
6
votes
1answer
146 views
What does “running in polynomial time” really mean?
I'm currently learning private-key cryptography. I've been able to see that perfect secrecy is achievable if no assumption is made about the computational power of the attacker.
However, perfect ...
4
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1answer
98 views
Why should I use an Initialization Vector (IV) when I have unique keys?
I took a look at this question. My question is not the same.
I've unique keys encrypting (in CBC mode, AES-256) each plaintext, i.e. I do not use a key to encrypt more than one plaintext. Is it ...
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2answers
57 views
IV Security Clarification
After doing lots of reading on SO and other websites relating to AES cryptography, I am trying to understand the security issues surrounding IV's.
There seems to be a lot of confusion and ...
1
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1answer
71 views
How can I split a message in parts of similar size or smaller?
I have a 130-160 characters message that I need to split in say, 3 parts, and be able to reconstruct it by recovering all 3 parts. I also need that these parts are type-able, meaning that they can't ...
0
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0answers
53 views
Will D-Wave's quantum computers ruin classical encryption? [duplicate]
D-Wave has commercially available 512-qbit quantum computers now. A lot of big names are taking it seriously. Google, NASA, and USRA have joined forces to start a quantum AI lab.
How far are we ...
2
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3answers
171 views
If RSA is limited to 117-200 bytes or so, is that a very limited use case?
Am I missing something, or is RSA very very limiting when it comes to ecrypting data when it comes to the actual message size?
I have read that you can only encrypt a message of around 117 to 200 ...
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2answers
40 views
No IV for one off symmetric file encryption
My question is (hopefully, for somebody) a simple one; but my project is holding as I'm not sure.
I read on SO that generating encryption keys without an IV is a bad idea, so is using a constant IV ...
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votes
0answers
63 views
Certificateless Cryptography for Wireless Sensor Network [closed]
As we all know that ID-based cryptography has been implemented for wireless sensor networks, can we implement certifficateless cryptography over that? Discuss pros and cons.
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1answer
96 views
Best way to create password manager [closed]
After some searching I wasn't able to find a password manager that fits me (able to sync from my own server, open-source, secure enough and browser auto complete). So, I thought that I will create ...
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votes
0answers
47 views
can we do double encryption of a message without first key?
Lets assume $k_1$, $k_2$ are two keys and there can be any relation between them like $k2 = E(k1) $ that is key $k_2$ is encryption of $k_1$ using some other long term key or any other relation.
...
1
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0answers
64 views
How well analyzed are giant block length ciphers?
I have heard about ciphers that have a block length of 256 megabytes... That is huge.
How well are they understood by the encryption community?
I'm referring to PMC Ciphers.
Has anyone used such a ...
1
vote
1answer
69 views
AES encryption with multiple keys
I would like to encrypt some data using a combination of multiple keys. There would be two keys: a client keys that would be generated for each client and a single server/application key used by ...
2
votes
1answer
83 views
Encrypt user email but be able to find user by email
Sorry for my dumb question, but it's better to ask dumb question than to do dumb things silently.
I want to encrypt user email in my DB so that if someone stole the DB (and not the key) - he won't be ...
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0answers
30 views
Conditions for proving that a signcryption scheme is secure
If I'm able to prove that any scheme satisfies confidentiality ad unforgeability conditions, will it be a valid signcryption scheme, without explicit signature and encryption parts ?
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1answer
75 views
Which keys are necessary to decrypt Application data in a SSL connection?
I'm debugging an application which communicates between client and server using a SSL/TLS connection, and want to capture and analyze the sent data.
Are the client write keys and server write keys ...
-1
votes
1answer
59 views
what actually the function for e(g,g)^xy
I doing a project using ABE "Attribute-Based-Encryption" but i didn't understand what actually the function for $e(g,g)^xy$.
Just tell what's the calculation need to perform here. I gone through no of ...
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votes
0answers
59 views
sir,please suggest me an algorithm or method how can i improve the prediction based encryption method using randomization? [closed]
I am doing research on security for data migration in cloud computing. I have gone through many encryption algorithms to secure data for migration, but I want to create my own algorithm that could be ...
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votes
2answers
102 views
Proper Way to Encrypt Data with Two Keys?
I'm going to develop a system that will have two keys. One supplied and generated by the system that's specific to an individual user and one from the user.
I plan on using AES.
Does it make sense ...
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votes
0answers
75 views
Decrypting the Encrypted hex applcation data with encryption keys [closed]
I am having all the keys,
...
0
votes
2answers
132 views
Physical Level Encryption
What types of algorithms that are capable of signing a message are out there that run on a physical level, e.g. lacking the infrastructure of a standard PC, no memory, processor or motherboard in the ...
0
votes
2answers
79 views
Why this k parameter is in unary in adversary PPT algorithm? [duplicate]
While reading some text on cryptography, I found that algorithm $A$, that the adversary (called Eve by convention) runs to break the cipher message, needs two parameters, candidate message ($y$) and ...
3
votes
1answer
122 views
Alternatives to HMAC + CBC?
I'm looking at using HMAC + CBC. The combination looks like this:
ciphertext = AES256(text, k1)
data = HMAC-SHA256(iv | ciphertext, k2) | iv | ciphertext
Where:
...
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2answers
102 views
Generate fixed length cipher text from arbitrary length plaintext
Using an encryption algorithm like AES, is it possible to generate a fixed length cipher text no matter how long the plain text becomes?
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1answer
70 views
Can someone help with the following hashes? [closed]
Here are a couple of hashes. I feel it should be easy (simple base conversions?) to decode them but I haven't succeeded so far. Can someone help?
...
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1answer
89 views
Security of Salsa20 with some known plaintext?
Basic question- if I'm encoding a bunch of known filetypes with salsa20, will it still be secure if the plaintext header is known?
Assume that a different IV and Key are generated before each file is ...
1
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1answer
127 views
Indistinguishability attack example
I want solve the next exercise. The author defined the experiment for the cryptosystem $\Pi$, the adversary $A$ and the security parameter $n$ as follows
$\mathsf{PRIV_{EAV}}(\Pi,A,n)$
The ...
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votes
1answer
92 views
What length should the padding be when encrypting or signing with RSA?
Does it matter what length the padding is? If so - what length should it be?
(Another point: Should it be random?)
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1answer
122 views
Encrypt a single file, chunk-by-chunk, each chunk using different key (AES)
Encrypt a single file, chunk-by-chunk, each chunk using different key.
I am a security newbie (only took 2 security courses before)
But currently I am using this encryption method for my Android ...
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votes
2answers
55 views
Book Didactic Security Notions [closed]
I want study more about cryptography reading papers, but I have a problems to understand few concepts: security notions, random oracle model, IND-CCA, ... etc. I began study this concepts by internet: ...
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2answers
95 views
How to compare two datasets „anonymously”?
Ok, I hope this question makes some sense because I am not so sure how to word it any differently… Imagine the following situation:
There are 10 defined colors (blue, orange, yellow etc.)
There are ...
0
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2answers
247 views
Custom crypto library in C
I will be making (in the near future) an app that will contain some pretty heavy crypto. As it is possible that my app will be ported to different devices (initially it will be iOs only, but Mac, ...
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votes
1answer
41 views
Determine the Identity of Caller [closed]
Let me explain my situation.
I have a provider which is made up of a registration page and a web service. Online vendors (clients) register with the provider by providing details such as username, ...
0
votes
1answer
99 views
RSA - Ecrypting the same data with the same public key = same ciphertext?
If an adversary knows my public key and guesses what was my plaintext, can he test for it somehow?
The most obvious way is encrypting the guessed plaintext with my public key and the same parameters ...
3
votes
1answer
166 views
Secure encrypt-then-sign with RSA
I understand that when you want to encrypt and sign data with RSA the generally recommended approach is sign-then-encrypt.
However, I have encrypted data that I need to sign, to prove the author of ...
1
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0answers
68 views
Is OAEP reversible?
Given nothing more than some integer $m =$ OAEP($M$), is it possible to recover the original plaintext $M$? In other words, without being given the hash functions or the random string used for ...
3
votes
1answer
85 views
implementing long term archive encryption
Let's say I want to create private archives for the long term (e.g. more than 30 ). The archives' sizes could be anywhere from 1 GB to 30 GB. As far as I understand I could go down two ways:
The ...
6
votes
1answer
455 views
repeating-key xor and hamming distance
I read that to break repeating-key xor you can do the following: try a keysize $n$ and compute the hamming distance between the first $n$ bits of the encrypted string and the bits $n+1$ to $2n$ of the ...
3
votes
1answer
120 views
Combining AEAD with RSA
'Hybrid' encryption, where we combine symmetric encryption with public-key cryptography, is pretty 'tried and tested'.
To summarise, we generate a symmetric key and encrypt it using RSA. We would ...
3
votes
2answers
76 views
GPG and PAR2 error correction data from the plain archive, will it compromise security?
I have the following scenario:
Archives compressed with 7z, hundreds of MiB in size
GPG to encrypt the archives (binary, without ASCII armor)
PAR2 to create error correction data
Question
1. ...
2
votes
2answers
107 views
Keys required for cryptography
I am reading an article on cryptography at following location:
http://www.entrust.com/resources/pdf/cryptointro.pdf
Historically, encryption systems used what is known as symmetric cryptography. ...
2
votes
0answers
72 views
How can I prove that this encryption scheme from a random oracle is secure?
I am reading this example:
A random oracle is an ideal object.
What makes a random oracle convenient for proofs is the part about knowing nothing on the output for a given input if you do not ...
