Information security technology and its application public key encryption technology

first, public key encryption technology 1.2 Principles of the Public Key cryptography system

Public Key Cryptography : Using different encryption keys and decryption keys is a cryptographic scheme that derives the decryption key from a well-known cryptographic key that is computationally infeasible.

1. Characteristics of public key cryptosystem:
-(1) The public key algorithm is based on mathematical functions rather than substitutions and permutations.
-(2) The key is asymmetric and uses two different keys, which has far-reaching effects on the fields of secure communication, key distribution and identification.
-(3) Successfully solved the problem of network identification, digital signature and so on.
-(4) Make Key management easy.
-(5) encryption and decryption are slower than the regular key cryptosystem.

2, public key password system General Description:
(1) In the public key cryptography system, each user has two different keys: the encryption key and the secret key.
(2) The user's encryption key disclosure (public key), can be publicly published on the key book, by all users access, the user's decryption key is saved by themselves and strictly confidential (private key).
(3) The transmitting end with the receiving end of the encryption key PK to clear-text m encryption, generate ciphertext C transmission, the encryption transformation is recorded as: C = EPK E_{p_k} (M) the receiver with its own decryption key SK to the ciphertext C decrypted by the plaintext m, the decryption transformation is recorded as: M = DSK D_{s_k} (C).
(4) The encryption transform and decryption transform of public key cryptosystem should satisfy:
A, the decryption transformation is the inverse transformation of the cryptographic transformation: DSK D_{s_k} (EPK E_{p_k} (M)) =m or EPK e_{p_k} (DSK D_{s_k} (C)) =c
b, known encryption key, EPK E_{p_k} (M) easy to calculate; known decryption key DSK D_{s_k} (C) is easy to calculate.
C, from the known PK can not deduce the SK S_k, or from the PK P_k derivation of the SK S_k is not feasible in the calculation.
(5) The encryption key cannot be used to decrypt: DPK D_{p_k} (EPK E_{p_k} (X))!=x.
(6) On the computer can be easily generated on the property of PK P_k and S