RSA

1
RSA

• Rivest Shamir Adelman
• Patented in 1983, expired in 2000
• Based on difficulty of factorization
• Choose two large random prime numbers p and q,
• Compute n pq
• Compute f(n) (p-1)(q-1)
• Choose an integer e, such that e, is coprime to
  f(n)
• -- e, is released as the public key
• Compute d, to satisfy (de) mod f(n) 1
• -- d, is kept as the private key

2
RSA

• Encryption (of message m)
• (m)e mod n
• Decryption (of cipher m)
• (m)e mod n
• RSA property
• ((m)e)d mod n m