"Summarize and organize" Http-https

The way you encrypt the message above is symmetric encryption , you know how to encrypt it, and you know how to decode it. Then Li Lei and Han Meimei use the alphabet Offset encryption method called Caesar cipher, Caesar encryption . Cryptographic algorithms in the real world are more complex, but the fundamentals are the same.

The above encryption method is asymmetric encryption , asymmetric meaning relative to symmetry, is you even know how to encrypt the way, do not know how to decrypt, corresponding to the above process is Li Lei password box but no way to open.

In terms of terminology, we know the public key and private key , the server sends the public key (lockbox) to the client, the client uses the public key to encrypt the information (Lock the box), the server accepts the message and uses the private key (only Han Meimei known password) to decrypt.

Certification Authority, Certification body, has the right to issue a certificate (signature).

In this relationship chain, Trust CA is the basis, because, in fact, there will be a CA tell you that he is safe , he will give himself a certificate. In the corresponding example, if Jim Green is a credible person and then signs himself, then there is no play, but we "believe" the CA will not do such a bad thing, so Jim Green will not be a CA.

As a result, they decided that the message body is still transmitted in the form of Caesar encryption, and then the offset step is sent in a Zheng signed safe, which balances the security of the message and the cost of the transmission.

The term interpretation is that asymmetric encryption can affect the transfer speed, because the message body is larger, so generally comprehensive performance and security considerations, the symmetric encryption of the message body , asymmetric encryption is used to encode the symmetric encryption key.

"Summarize and organize" Http-https