Data encryption technology and identification technology simple self-knot

First, encryption technology

1. General Data encryption model

Note that there is a key on the A and B side.

2. Two Class cipher system

A) symmetric key cryptosystem and public key cryptosystem are divided according to whether the encryption key and decryption key are the same.

b) in a symmetric key cryptosystem, the encryption key at the end of a and the decryption key at the B end are the same. This kind of commonly used encryption algorithm has DES,IDEA,AES and so on

c) The cryptographic key and decryption keys are not the same in the public-key cryptography system. RSA and DSA encryption algorithms belong to asymmetric encryption algorithm

D) The Public key cryptography scheme is shown below:

Graphic:

1) generate a pair of keys on the receiver B side through the key pair generator, namely the encryption key PK and decryption key SK. The PK used by sender A is generated at receiver B.

2) key pair generated by the generator, encryption key PK, is public, so the abbreviation for the public key. And the decryption key SK is required to be confidential, so referred to as the private key.

f) The most well-known cryptographic algorithm for public-key cryptography is the RSA encryption algorithm proposed by the American three scientists Rivest,shamir and Adleman in 1976-1978, which is based on the large number decomposition problem in the theory of numbers.

Second, identification technology-digital signature

Communication between the 1.a,b. Digital signature is to let recipient B when receiving data, it can be concluded that the data is from sender a.

2. Digital Signature Implementation diagram:

Tips: Here are the D and e operations, which are not the same as the illustrations above, because they have different meanings. The digital signature is the related process of asymmetric encryption, which only has the function of authentication and no encryption. Just to identify the data is from a certain subject. Anyone on the network can use the public key to decrypt the digital signature.

3. Graphical representation of digital signatures with cryptographic effects:

Third, off-topic

In GitHub, SSH key is set when you communicate with SSH. In fact, is the use of public key cryptography RSA encryption algorithm, local public key set to the server, in order to achieve encrypted transmission.

Study Data Source: Computer network Fifth edition (Shehiren)