Cryptographic functions which transform plaintext into ciphertext or the other way around.
1
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0answers
14 views
Are there any hand ciphers not obsoleted by computer cryptanalysis?
Computerized cryptanalysis has obviously made formerly "secure" hand ciphers like Playfair, Four Square, and the Hill Cipher obsolete because they can be defeated in seconds. But is there a hand ...
1
vote
1answer
67 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
votes
0answers
35 views
Interesting game: decipher the following sequence [closed]
Decode the following sequence:
KROWE
MOHSI
HTDEY
OJNEI
The original cipher is printed in such matrix format
-1
votes
1answer
40 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, ...
2
votes
1answer
109 views
Is this hand cipher any more secure than the Vigenère cipher?
I know that inventing one's one crypto always sucks, but the problem is that hand ciphers are usually 1. very insecure 2. very slow. This is an attempt to make a relatively secure, keyable, and ...
3
votes
1answer
90 views
When confusion is applied during encryption?
I know confusion is used in cryptography to make it more difficult to identify any
relationship between the ciphertext and the symmetric key. I want to know when the confusion is applied during ...
1
vote
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 ?
3
votes
4answers
136 views
Turning a cipher into a hashing function
This is theoretical question. I'd like to know if it's possible (and what are eventually the consequences), not that I'm going to do it in one of my projects. ;)
The first hashing functions created ...
1
vote
1answer
81 views
Symmetric encryption mode where ciphertext size is plain text size
I've had many questions on Stackoverflow on how to minimize the output of a cipher - during encryption of course - to the same size as the input. Obviously this is possible for a single block of ...
-1
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 ...
-2
votes
1answer
89 views
What is the most paranoid way to exchange messages? [closed]
I'm looking for a way for Alice to send a message or a file to Bob in the most paranoid way possible (over the internet).
It can be asymmetric or symmetric. But According to some articles, AES ...
3
votes
2answers
331 views
Difference between symmetric and asymmetric hash function?
The Linux kernel supports symmetric and asymmetric hash functions. E.g. sha1, sha256, ...
See tcrypt.c and search for test_hash_speed and ...
-2
votes
1answer
143 views
How does one find out ciphers/passwords without knowing what cryptographic algorithms are used?
If one does not reveal what cryptographic algorithms are used, how does a cracker find out a password/cipher that is used to communicate data? I heard that because there are methods to try cracking ...
0
votes
2answers
205 views
Could the Enigma algorithm be classified as a Feistel network?
The Enigma algorithm is a encryption method that was developed (I believe) by the Germans in WWII. It went a little something like this:
When a letter was typed on the keyboard of the Enigma ...
0
votes
0answers
102 views
How do you decrypt a ciphertext that is made up of special characters? [closed]
When you have a cipher text that is made up of special characters and spaces, how do you decrypt that it back to its original state?
6
votes
2answers
338 views
What's is the main difference between a key, an IV and a nonce?
What are the main differences between a nonce, a key and an IV. Without any doubt the key should be kept secret. But what about the nonce and the IV. What's the main difference between them and their ...
0
votes
2answers
215 views
Making a cipher (ex: Vigenere) harder to break
The Vigenere cipher can relatively easy be broken when the key size is small compared to the size of the message. One first finds the length of the key, and then uses frequency analysis to actually ...
0
votes
1answer
121 views
How to plot the distribution of a ciphertext?
Is there any plot or visualizing program that can plot the distribution of a plaintext and then the distribution of the ciphertext after applying a ciphering encryption algorithm? I am interested ...
2
votes
2answers
756 views
How many keys does the Playfair Cipher have?
I was just studying the Playfair cipher and from what I've understood, it is just a slightly better version of a Caesar cipher, in that it isn't actually mono-alphabetic but rather the 'digrams' are ...
10
votes
3answers
439 views
Could one construct a cipher that is secure for friendly parties to use but insecure for hostile parties?
Consider the situation of a nation state (Blue) at war with another nation state (Red). Blue wants to deploy a secure cipher that blue currently can not break, but they are considered that Red could ...
0
votes
1answer
97 views
How do I calculate the maximum plain text length allowable for a certain cipher text length?
I am encrypting and storing sensitive values in the database. I have a set max length in the database, but in order to provide useful user feedback, I'd like to know the max input I should allow for a ...
1
vote
3answers
292 views
Relative security of a Vigenère cipher
Within a closed computer network, I am ciphering some plaintext data as an added security measure. This is below several other layers of protection. For various technical reasons, I am restricted to ...
1
vote
3answers
167 views
Looking for cipher that uses one ciphertext
I'm new to Cryptography so please free to edit my question for clarity and add the appropriate tag.
I'm trying to research if the following is possible. Suppose
John has a message that he ...
1
vote
1answer
72 views
Incorporating known ciphertext into new message
Which ciphers $c_k$ enable one to define a joining function $f_{c,k}$ such that:
$$
f_{c,k}(c_k(p_1), p_2) = c_k(p_1 + p_2)
$$
That is, the result of joining some known ciphertext $c_k(p_1)$ with a ...
2
votes
1answer
129 views
Transparent cipher
I'm trying to implement this protocol:
Alice has her permanent key $K_1$. She computes $E(K_1, P)$.
She wants to share $P$ with Bob, Carol and Dave. For each of them she:
2.1. Generates $K_2$.
...
0
votes
0answers
48 views
what is the required protocols to make share the key? [duplicate]
Possible Duplicate:
gererating session key using diffie hellman algorithm?
The first subnet have three nodes (A,B,C) they are connected to second subnet via (C-E), the second subnet consist ...
0
votes
1answer
175 views
Why does my implementation of CBC mode only decrypt the first block correctly? [closed]
I have the following code that uses a CBC mode to encrypt a text by dividing it to 3-elements block. But it only works correctly on the first block which is xored with the IV.
...
1
vote
1answer
146 views
Which encodings have |encoding key| >> |decoding key|?
I'm looking for an encoding scheme that requires a very large encoding key E (>10MB) and suffices with a relatively small decoding key ...
3
votes
3answers
582 views
A simple block cipher based on the SHA-256 hash function
I've come up with this little routine for doing encryption using the SHA-2 (in this case SHA-256) hash function. As such it is a block cipher with a 256 bit (32 byte) block size and an arbitrary key ...
8
votes
1answer
397 views
How can I make my cipher show the avalanche effect?
I am a beginner in cryptography. I designed an password based encryption-decryption algorithm, which uses a random salt and a password to encrypt a message. I'm using SHA-512 for hashing, matrix ...
3
votes
1answer
228 views
What is the best method to determine the language used in a monoalphabetic substitution cipher?
Working on a cipher (which I assume to be a mono-alphabetic substitution cipher due to the letter frequency) I struggle with the fact that I don't know which language the plain text is written in. ...
