RSA (Rivest -Shamir-Adleman )

Algorithm:

• key generation

Step1: Choose p, q where p and q are prime ,and

calculate n=pq.

Step2: Select e such that gcd(e, f(n))=1

where f(n)=(p-1)(q-1)

Step3: Calculate d=e -1 mod n

Step4: your public key {e,n} : public

your secret key {d,n} : keep secret by yourself

• Encryption

C = M e mod n

• Decryption

M = C d mod n

where M: Plaintext and C: Ciphertext

• key-length >=512 bits

• Public key encryption algorithm (Asymmetric) ,1977

Encryption

algorithm

Decryption

algorithm

M

M

C

A

B

( B, eB , nB )

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