复旦大学：《密码学基础》课程教学资源（课件讲稿）04 Public Key Cryptography, RSA

密码学基础(04) Public Key Cryptography, RSA 復大辱软件学院 LiJT

LiJT 1 密码学基础（04） Public Key Cryptography, RSA

Public Key Cryptography Principles of Public-Key Cryptosystems The rsa algorithm 復大辱软件学院 LiST

LiJT 2 Public Key Cryptography • Principles of Public-Key Cryptosystems • The RSA Algorithm

e Review: Symmetric Cipher Model Secret key shared by Secret key shared by sender and recipient sender and recipient Transmitted ciphertext Plaintext Plaintext Input Encryption algorithm Decryption algorithm output (e.g, DES) (reverse of encryption algorithm) Bob Alice 3 復大辱软件学院 LiST

LiJT 3 Review: Symmetric Cipher Model Bob Alice

ota Symmetric Cryptograph traditional symmetric/secret/single key cryptography uses one key shared by both sender and receiver if this key is disclosed communications are compromised also is symmetric, parties are equal 復大辱软件学院 LiJT

LiJT 4 Symmetric Cryptography • traditional symmetric/secret/single key cryptography uses one key • shared by both sender and receiver • if this key is disclosed communications are compromised • also is symmetric, parties are equal

ef Review: Symmetric Cipher Model Secure channel Secret key shared by Secret key shared by sender and recipient sender and recipient Transmitted ciphertext Plaintext Plaintext Input Encryption algorithm Decryption algorithm output (e.g, DES) (reverse of encryption algorithm) Bob Alice 5 復大辱软件学院 LiJT

LiJT 5 Review: Symmetric Cipher Model Secure channel Bob Alice

o Asymmetric Cipher Model Every body have two keys Public key—公开 Private key-保密 Bob Alice 復大辱软件学院 LiJT

LiJT 6 Bob Alice • Every body have two keys – Public key —— 公开 – Private key —— 保密 Asymmetric Cipher Model

o Asymmetric Cipher Model 公开 t Bob's Public key Alice's Public key Bob's private key Alice's Private key Bob Alice 復大辱软件学院 LiJT

LiJT 7 Bob Alice • Bob’s Public key Alice’s Public key • Bob’s Private key Alice’s Private key Asymmetric Cipher Model 公开

o Asymmetric Cipher Model 公开 t Bob's Public key Alice's Public key 保密 保密 Bob's Private key Aice's Private key Bob Alice 復大辱软件学院 LiJT

LiJT 8 Bob Alice • Bob’s Public key Alice’s Public key • Bob’s Private key Alice’s Private key Asymmetric Cipher Model 公开 保密 保密

o Asymmetric Cipher Model B oDS S public key ring Ted Mike Alice Alice's public Alices private k key 圄「 Transmitted cipherte Plaintext Plaintext Input Encryption algorithm Decryption algorithm output (e. g, RSA) (reverse of encryption algorithm) Bob Alice 9 復大辱软件学院 LiJT

LiJT 9 Asymmetric Cipher Model Bob Alice

o Cryptography Catalog The number of the keys used Symmetric, single-key, secret-key, conventional encryption: Both sender and receiver use the same key Asymmetric, two-key, or public-key encryption: the sender and receive each uses a different key 復大辱软件学院 LiST

LiJT 10 Cryptography Catalog • The number of the keys used – Symmetric , single-key, secret-key, conventional encryption: Both sender and receiver use the same key – Asymmetric, two-key, or public-key encryption: the sender and receive each uses a different key