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revised Convert ciphertexts of one encryption scheme to another without decryption
Fixes
Feb
6
comment How to break Universal Re-Encryption algorithm?
Nope, not without the group. But here you assume that all public keys share the same group parameters and thus the description of the group is known, but not the individual public key.
Feb
6
revised How to break Universal Re-Encryption algorithm?
added 145 characters in body
Feb
6
answered How to break Universal Re-Encryption algorithm?
Feb
2
comment Status of Algebraic Eraser key exchange?
That seems to be pretty devastating: eprint.iacr.org/2016/091
Jan
28
comment Is H'(M)=5*M + 9*H(M) mod 2^n a secure hash?
I see. What's the purpose of this hash function if you need to assume a secure hash function for its construction?
Jan
28
comment Is H'(M)=5*M + 9*H(M) mod 2^n a secure hash?
en.m.wikipedia.org/wiki/Diophantine_equation
Jan
27
answered What is an example of a secure sigma proof?
Jan
23
answered Discrete logarithm hash function Exercises
Jan
19
comment Non-numeric Diffie-Hellman?
Yes thats true for one class of suitable groups (as stated at the end of my comment). But the first sentence in your answer is not correct. You should rather say: Diffie Hellman is used in a setting where one represents the involved elements as positive integers.
Jan
19
comment Non-numeric Diffie-Hellman?
Diffie Hellman does not rely on a mathematical problem of positive integers. It relies on a problem (CDH) in discrete log hard groups. It happens that among such groups (besides elliptic curve groups) are the multiplicative groups of prime fields of large prime characteristic $p$ and that are the integers from $1$ to $p-1$.
Jan
14
comment Are all points in a cyclic group in ECC pre-calculated?
en.wikipedia.org/wiki/Elliptic_curve_point_multiplication
Dec
19
comment Zero-Knowledge Proof of a polynomial
@Hongyang The value $c$ is secret?
Dec
16
comment textbook RSA signature scheme security
If the adversary is given $(e,N)$ and a message $m$ and outputs a valid signature for $m$, then you can directly use this adversary to break the RSA assumption.
Dec
15
revised textbook RSA signature scheme security
added 10 characters in body
Dec
15
answered textbook RSA signature scheme security
Dec
14
reviewed Leave Open Public key exponent coprime with totient proof
Dec
4
comment (Looking for reference) Variants of Diffie-Hellman
It's no longer available as html, but you can obtain it as a pdf here.
Nov
29
comment paradox on fully homomorphic equality checking
How should the server learn the result if it cannot decrypt? Your setting as it is does not really make sense . What would the server return? If you want to have keyword equality, look for searchable encryption.
Nov
25
comment Confused about how chosen ciphertext attacks work?
Just to recall what CCA requires. The OP should already have this question when looking at CPA...