利用公开密钥密码算法，加密和解密使用不同的密钥。

（1）使用密钥PK对明文加密后，在用解密密钥SK解密，可得到明文，

DSK（EPK（X））=X

（2）加密密钥不能用来解密，DPK（EPK（X））！=X在计算机上可以容易的产生

成对的PK，SK，从已知的PK实际上不可能推导SK

（3）加密和解密的密钥可以对调，即EPK（DSK（K））=X

（4）从PK到SK的推导过程是几乎不可能的-The use of public key cryptographic algorithm, encryption and decryption use different keys. (1) the use of explicit encryption key PK, the decryption key SK using decryption, can be explicitly, DSK (EPK (X)) = X (2) can not be used to decrypt the encryption key, DPK (EPK (X) )! = X on the computer can easily have a pair of the PK, SK, the PK from the known fact can not be derived SK (3) encryption and decryption key can be reversed, that is, EPK (DSK (K)) = X ( 4) from PK to SK derivation process is almost impossible