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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Is Convergent Encryption really secure?
Recently a company called Bitcasa demonstrated a product of cloud storage. they indicated that they would use "Convergent Encryption" to secure your data and de-duplicate, essentially one copy of the ...
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1answer
32 views
decrypting unreadable string [closed]
Does anyone recognise this type of encryption? These are phone numbers consisting of 10 digits and starting with 0 but the encrypted text width is not 10 and does not start with the same character.
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3answers
448 views
Is this encryption algorithm build from MD5 secure?
I'm being asked to use an encryption algorithm in my code, and besides the fact that I'm sure there will be implementation faults that lead to vulnerabilities, I also have concerns about the algorithm ...
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1answer
46 views
Solving congruences using PARI
I'm having trouble finding info in the docs about how to solve a system of congruences. The closest I can find is 'matsolvemod' in here: ...
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1answer
53 views
What is total key space in transposition algorithms
How we can measure key space in transposition algorithms? Should we specify the method, like rail fence ?
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1answer
181 views
Low Public Exponent Attack for RSA
I'm having trouble understanding the algorithm for finding the original message $m$, when there is a small public exponent. Here is the example I'm trying to follow (you can also read it in the 'Low ...
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1answer
321 views
Is a steganographic technique which has a universal decoder novel/secure? [closed]
I've come up with an approach to steganography which needs review of both its cryptography and its math. There's a complete working implementation at https://github.com/bramcohen/DissidentX and the ...
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2answers
104 views
Strong encryption done by hand [duplicate]
One of the distinguishing features of a good encryption algorithm, is that it is easy to encrypt, and hard to crack. Are there any that are easy enough for average folk to remember, and calculate by ...
2
votes
1answer
151 views
Encrypting many small messages (log-lines)
What would be the best way of encrypting small mesasages to be stored in encrypted form? (This sounds like somthing a textbook would cover, but I haven't found any references).
Let's say I have many ...
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0answers
54 views
What is the significance of i^Q mod P = 1 and are there any special properties to be aware of?
I'm studying UProve, and one of the fundamental components of this technology is based upon the relationship between
i^Q mod P = 1
Lacking a specific name I can call this mathematical ...
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2answers
135 views
Zero-Knowledge Challenge-Responce Protocol
Good day to everyone.
I am trying to implement an e voting system (just for reference -it is not important though-it is described at the Internet Voting Protocol Based on Improved Implicit Security ...
1
vote
2answers
210 views
Would a “Triple AES” (in the sense of how Triple Des works) serve for a dramatic increase in safety?
The system requires to be as paranoid as possible regarding security. One of the few contemplated changes to the current design is to use multiple encryption. First proposal was to use Serpent on top ...
2
votes
1answer
198 views
XOR cipher for encrypting compiled C code
I'm exploring ways of encrypting Intel hex files we send to customers for flashing onto an embedded device. The embedded processor itself has a built-in mechanism that prevents anyone from reading the ...
0
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1answer
61 views
GPG vs PGP vs OpenSSH and management of them
What is the main difference of the three?
Can I use only one of them for everything (e.g. GPG for SSH authentication)
If I encrypt my private key with a pass-phrase, is it strong enough so that if ...
5
votes
1answer
489 views
Why is CAMELLIA suddenly so widely used?
When nowadays I point my browser to https sites, the cipher that is on most occasions used is Camellia. My browsers (Chrome and Firefox) seem to prefer it, even when AES is available.
Is that not ...
3
votes
3answers
169 views
Why do we assume un-security of communication channel on every cryptography system
While reading about a few cryptographic systems, I noticed that we always assume the communication channel is not secured. Why is this assumption made? And, why the effort is being put into designing ...
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2answers
60 views
Is it safe for the ChaCha8 nonce to be deterministic?
ChaCha8 takes a 8 byte nonce (or IV) that should not be the same twice for the same key. Generating this nonce randomly makes me very very nervous for collisions.
Is it safe to generate this nonce ...
4
votes
1answer
136 views
Question about why RSA is hard to attack
I think I understand why RSA is hard to attack but I'd like to get clarification if I actually do.
Assume there are two people, Alice and Bob, who are attempting to communicate privately but that we ...
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4answers
174 views
Bad/Crackable Encryption Example?
I've been tasked with building up some security exercises (basic CTF training kind of stuff) for work. This should contain a bit of crypto, but my knowledge in this space has been limited to using the ...
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1answer
41 views
Security system theoretical task [closed]
Imagine that you are responsible for implementation of a new security system in a company which boss insists on having new encryption algorithm.
Here are couple of solutions which has been presented ...
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1answer
98 views
What is a good intro to cryptography book? [closed]
I'm a math major in college and its mostly theoretical like analysis, etc. and I have been interested in the idea of cryptography, so naturally I'm interested in possibly studying up on it a litle bit ...
2
votes
1answer
258 views
How does Output Feedback mode use the initialization vector?
How can I process Initialization Vector inside the Block Cipher Encryption box (using for example AES) together with the Key?
Will I encrypt the Initialization Vector like a block of plaintext?
So ...
3
votes
1answer
92 views
Low complexity implementation of a small blocksize cipher (< 64 bit)
Searching for "small blocksize cipher" finds a number of discussions on the topic, mostly refering to FPE.
This one in particular suggests using AES as the round function of a Feistel network.
The ...
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1answer
152 views
How to break AES CBC with PKCS#5 padding?
If I have a string encoded with AES CBC with PKCS#5 padding, how can one possibly decrypt/crack it? What are the approaches that one can take to break its security?
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1answer
91 views
ASCII Message in TV show? [closed]
So I was watching a popular series tonight (Person Of Interest) when suddenly during a frame change I noticed a very quick blue screen with writing.
At the time I never thought anything of it as it ...
4
votes
3answers
899 views
Why programming languages don't provide simple encryption methods?
In c#, there is a namespace called System.Security.Cryptography and there are many classes in this namespace, which help developers encrypt and decrypt data. ...
4
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3answers
316 views
How and why can a decryption program tell me that a key is incorrect?
I have noticed that some programs used for file encryption will tell you if an entered key is wrong when you try to decrypt. It seems (to me at least) that this would mean that the key somehow is ...
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1answer
118 views
Request for 1024-bit primes $p$ , subgroup $q$ and subgroup generator $g$
I need to find a prime $p$ of $1024$ bits with a $160$ bit sub group size $q$, such that $q|p-1$ , and $g$ is the generator of the sub group size $q$.
I'm looking for the numeric values of $p$ , $q$ ...
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votes
1answer
341 views
How to break an arbitrary XOR and Rotation based encryption?
I heard encryption based purely on XOR and Rotation is inherently weak. The paper Rotational Cryptanalysis of ARX says:
It is also easy to prove that omitting addition or rotation is devastating, ...
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votes
1answer
116 views
How to bring little changes in DES algorithm
I thought of implementing DES modes of operation as a project...But my guide asked to change or to modify the DES algorithm in such a way to overcome drawbacks of DES...So is there any way to do ...
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2answers
175 views
Two step encryption
Is there any asymmetric cryptography algorithm which will allow recursive encryption.
...
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3answers
191 views
How to check the strength of an encryption algorithm?
I asking for advice on how to check strength of an encryption algorithm.
4
votes
1answer
101 views
What is 'security margin'?
I have been academic papers about Rijndael, Serpent, and Twofish, and there is this term that is vague to me. I cannot find a tangible definition in google. Can someone briefly define, describe, ...
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votes
1answer
95 views
AES implementation in java that allows key of 320-bit length [closed]
I need an implementation of AES(Rijndael) in java that allows use of a 320-bit key.
Please suggest a reliable implementation
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2answers
115 views
FIPS 140 compliance for encrypted files
Does FIPS 140-2 require specific key sizes, or does it have specific requirements for the data?
In other words, if I encrypt a file, how I can check whether it is FIPS-compliant or not? Does only the ...
2
votes
2answers
169 views
Why does the recommended key size between symmetric and assymetric encryption differ greatly?
In various articles it is mentioned that for secure communications, the recommended key sizes are 128-bit key size for symmetric encryption (which makes it $2^{128}$ possible keys?) and 2048-bit key ...
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2answers
150 views
Is such a crypto-system available?
$E(k_1, pt) = c_1, E(k_2, c_1) = c_2, D(k_{new}, c_2) = pt$, where $k_{new} = f(k_1, k_2).$ Sharing $k_{new}$ and $k_2$ should reveal no information about $k_1$.
Clarifications:
Being able to ...
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1answer
400 views
How do I derive the time complexity of encryption and decryption based on modular arithmetic?
I want to calculate the time complexity of two encryption and decryption algorithms.
The first one (RSA-like) has the encryption
$$ C := M^e \bmod N $$
and decryption
$$ M_P := C^d \bmod N. $$
...
2
votes
1answer
140 views
Visualization of cryptography
I think CrypTool is great software. And what I find most useful in it is visualization of algorithms such as Caesar, Vigenere, AES, DES. And my question is: does anyone know other tools which are ...
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1answer
97 views
How can encryption software accept password lengths which are not one of the AES key lengths?
AES comes with key sizes of 128, 192, and 256 bit.
But in Truecrypt or other crypto software we can use passwords of different length, even less than 128 bit or more than 256 bit.
How is this ...
4
votes
3answers
145 views
What is a block cipher?
I have read about block ciphers, but I do not understand the topic completely.
Is a block cipher a way to send data or a way to encrypt data?
How is the data divided into multiply blocks before it ...
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0answers
47 views
How compute encrypt and decrypt runtime for agorithm [closed]
I programming RSA algorithm is the following two function in java language in my thesis
...
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3answers
62 views
Secure communication between multiple peers on a public channel
I am wondering how can I secure communications between multiple peers over a public channel, like an IRC channel. With two peers it is easy - they exchange their encryption keys and decrypt the secret ...
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1answer
60 views
Cryptographic Primitive Method
Is there any cryptographic primitive bijective (one-to-one and onto) function for creating cryptographic tools like symmetric encryption/decryption, Hash code generator, MAC, HMAC and Random number ...
2
votes
1answer
90 views
Hashing a password with the password?
I was wondering if hashing a password with the password would be a good way of encrypting the password. So, the user must know his/her password to get the same result as the one in the database. Also, ...
4
votes
5answers
318 views
Using CBC with a fixed IV and a random first plaintext block
What if, instead of using CBC mode in the normal way with a random IV, I used this approach:
Use a fixed IV (like a block of 0's).
Before encrypting, generate a random block and prepend it to the ...
2
votes
0answers
46 views
Encrypting or HMACing password digests
Assuming I'm using bcrypt to digest passwords, is any additional security gained by either encrypting or HMACing the resulting digests? By requiring a key to compare password hashes, I would expect ...
0
votes
0answers
47 views
How compared encryption algorithm in terms of efficiency
I doing to compare two algorithm cryptography. first algorithm is RSA cryptography and second algorithm is El Gamal elliptic curve cryptography. now I want a way to compare between two algorithm by ...
2
votes
1answer
96 views
What does a “cycle” mean in cryptography benchmarks?
In this table, for example, cryptographic algorithm performance is measured in cycles per byte for symmetric ciphers, and in cycles per operation for asymmetric ciphers.
What does "cycle" here mean, ...
4
votes
1answer
79 views
Two way encryption with random IV
I'm attempting to encrypt some information into our database to be later pulled back out and displayed to the user. Searching and reading up on different methods I found a post over at stack exchanged ...
