传统密码的简化模型 Secret key shared by Secret key shared by sender and recipient sender and recipient Transmitted ciphertext Plaintext Plaintext nput Encryption algorithm Decryption algorithm output (e. g, DES) (reverse of encryption algorithm) Figure 2.1 Simplified Model of Symmetric Encryption wit 2021/1/27 Cryptography and Network Security-2 8812021/1/27 Cryptography and Network Security - 2 18/81 传统密码的简化模型