A mathematical function that is not reversible.
7
votes
2answers
328 views
What is a hard-core predicate?
I read this article on Wikipedia: Hard-core predicate.
Still I don't understand what exactly is a hard-core predicate. Is it possible to put this in simple English terminology, and perhaps with a ...
5
votes
2answers
213 views
Is there a hash algorithm that is slow to calculate but relatively fast to check?
Or more generally, is there a function or algorithm that is slow to calculate/execute, has a reliable execution time, and has a result that can be tested much more quickly than the calculation took?
5
votes
2answers
120 views
Pen-and-paper one-way function for externally-anonymous survey
When conducting surveys, an Administrator might send an Enumerator to survey a Respondent. For "sensitive" questions (e.g. about embarrassing behavior), the Respondent may be fine with the truth being ...
5
votes
1answer
598 views
Is the AES Key Schedule weak?
After reading this paper entitled Key Recovery Attacks of Practical Complexity on AES Variants With Up To 10 Rounds I was left wondering why the key schedule of AES is invertable.
In the paper the ...
4
votes
3answers
201 views
What other one-way functions are used in cryptosystems?
For RSA and El Gamal (and most other public key cryptosystems), one of the key ideas is that factoring and finding discrete logarithms are hard. There are other systems that rely on certain properties ...
2
votes
5answers
701 views
Are there hash algorithms with variable length output?
I understand that for example MD5 produces a 128 bit hash value from a given text of variable size. My question is if there is a hash-like algorithm that will produce a hash value where one can ...
2
votes
2answers
278 views
Lamport signature: How many signatures are need to forge a signature?
Lamport signature: Signing the message Note that now Alice's private key is used and should never be used again. The other 256 random numbers that she did not use for the signature she must never ...
1
vote
1answer
36 views
Pseudo Random Generator (PRG) from Rabin function
I'm trying to make a PRG using the Rabin function. The code (in Java) I wrote to implement the function is:
...
1
vote
2answers
203 views
Can one build a one-way function from AES?
We change the AES block cipher encryption:
we delete the key schedule algorithm
the user now provides a string of 1408 bits
we divide the string to 11 sub keys, and use them directly in the ...
0
votes
1answer
160 views
Hash collision resistance requirements for Lamport signatures
According to the original paper, Lamport one-time signature scheme uses two one-way functions: $F$ and $G$. The former one, $F$, is used to create a public key by hashing elements of the private key ...
-1
votes
1answer
68 views
Weak One Way Function
Show The function $mult(a,b)$ is weak one way if the Integer Factorization Assumption is true.
I am read the proof of this enunciated but I want know if I understand this in my way. The proof use the ...
