An small question about RSA algorithm

  • Context: Undergrad 
  • Thread starter Thread starter zetafunction
  • Start date Start date
  • Tags Tags
    Algorithm
Click For Summary

Discussion Overview

The discussion revolves around the RSA algorithm, specifically the choice of the public exponent \( e \) and its implications for the algorithm's functionality. Participants explore the conditions under which \( e \) can be selected and the consequences of certain choices.

Discussion Character

  • Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions why \( e \) cannot simply be chosen as 1 or 2, suggesting that it would simplify calculations.
  • Another participant argues that choosing \( e = 1 \) would render the algorithm ineffective, as the ciphertext would equal the plaintext.
  • A further explanation notes that \( e \) must be coprime to \( φ(n) \), which is derived from the distinct primes \( p \) and \( q \). It is pointed out that since \( φ(n) \) is even, \( e \) cannot be 2.

Areas of Agreement / Disagreement

Participants generally agree on the necessity of certain conditions for the choice of \( e \), but there is no consensus on the implications of choosing values like 1 or 2.

Contextual Notes

The discussion does not resolve the broader implications of choosing different values for \( e \) or the potential exceptions to the stated rules.

zetafunction
Messages
371
Reaction score
0
on the RSA algorithm

http://en.wikipedia.org/wiki/RSA

why simply we can not choose e=1 or e=2 ? it would simplify the calculations a lot.
 
Physics news on Phys.org
Does'nt that go against the purpose of the RSA?

edit: shady comma
 
If e = 1, then the ciphertext is the same as the plaintext, making the algorithm useless.

It's required that e is coprime to φ(n) = (p - 1)(q - 1), so that there exists d such that ed = 1 mod φ(n). However, if p and q are distinct primes, then one of them is odd, so φ(n) is even. Thus e can't be 2.
 
thanks a lot adriank , nice forum
 

Similar threads

Replies
5
Views
916
Replies
45
Views
7K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
Replies
14
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 12 ·
Replies
12
Views
3K
  • · Replies 2 ·
Replies
2
Views
3K