- #1

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- TL;DR Summary
- Understanding the RSA mathematics

Please help me understand the RSA encryption.

I understand part of it, then I don't understand.

Definitions:

M=plain text message

C=encrypted message

N=public key

E=encoding key

D=decoding key

P,Q are prime factors on N

I get that

P x Q = N (where P and Q are primes).

I get that

Φ(N) = (P-1) x (Q-1)

I get that

M

I get that

C

But after this I don't understand the relevance of this equation to solve D and E

D x E mod Φ(N) = 1

Seems to be some step or something obvious I'm missing?

I understand part of it, then I don't understand.

Definitions:

M=plain text message

C=encrypted message

N=public key

E=encoding key

D=decoding key

P,Q are prime factors on N

I get that

P x Q = N (where P and Q are primes).

I get that

Φ(N) = (P-1) x (Q-1)

I get that

M

^{E}modN = CI get that

C

^{D}modN = MBut after this I don't understand the relevance of this equation to solve D and E

D x E mod Φ(N) = 1

Seems to be some step or something obvious I'm missing?