复旦大学：《信息安全》教学课件_04 Public Key Cryptography, RSA

信息安全(04) Introduction to Cryptography Public Key Cryptography, RSA 復大软件学院 LiT

LiJT 1 信息安全（04） Introduction to Cryptography - Public Key Cryptography, RSA

eo Public Key Cryptography Principles of Public-Key Cryptos ystems · The rsa algorithm 復大软件学院 LiT

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

Cee 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 復大软件学院 LiT

LiJT 3 Review: Symmetric Cipher Model Bob Alice

想 Symmetric Cryptography traditional symmetriclsecret/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 復大软件学院 LiT

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

lot 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 復大软件学院 LiT

LiJT 5 Review: Symmetric Cipher Model Secure channel Bob Alice

oR Asymmetric Cipher Model Every body have two keys Public key—公开 Private key—保密 Bob Alice 6 復大软件学院 LiT

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

oR Asymmetric Cipher Model 公开 t Bob's Public key Alice's Public key Bob's Private key Alice's Private key Bob Alice 復大软件学院 LiT

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

oR Asymmetric Cipher Model 公开 t Bob's Public key Alice's Public key 保密 保密 Bob's Private key Alice's Private key Bob Alice 8 復大软件学院 LiT

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

oR Asymmetric Cipher Model Bobs public key rIng Oy STed Mike Alice Alice's public Alice 's private e ke Transmitted ciphertext Plaintext Plaintext Encryption algorithm Decryption algorithm (e. g, RSA) (reverse of encryption algorithm Bob Alice 9 復大软件学院 LiT

LiJT 9 Asymmetric Cipher Model Bob Alice

ef 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 復大软件学院 LiT

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