传统密码体制的模型 X k Messag Encryption Decryption I Destination Algorithm Algorithm K y= EK(X Secure channel X= DKo) Source Figure 2.2 Model of Symmetric Cryptosystem wit 2021/1/27 Cryptography and Network Security-2 20/812021/1/27 Cryptography and Network Security - 2 20/81 传统密码体制的模型 Y = Ek(X) X = Dk(Y)