Asymmetric encryption (1) Asymmetric encryption principle

Now we know that one of the biggest problems with symmetric encryption is how to transfer the key securely and not find a good solution in a symmetric encryption system. 1976, American scholar dime and Henman in order to solve the problem of information public transmission and key management, a new key exchange protocol is proposed, which allows both parties to exchange information on unsecured media and securely reach a consistent key, which is "public key System". This method is also known as "asymmetric encryption algorithm" relative to "symmetric encryption algorithm".

Unlike symmetric encryption algorithms, an asymmetric encryption algorithm requires two keys: the public key (PublicKey) and the private key (Privatekey). The public key and the private key are a pair, if the data is encrypted with the public key, only the corresponding private key can be decrypted, if the data is encrypted with the private key, then only the corresponding public key can be decrypted. Because encryption and decryption use two different keys, this algorithm is called an asymmetric encryption algorithm.

Asymmetric Encryption principle

Asymmetric encryption itself is not difficult to understand, combined with figure 6-14 on the process of asymmetric encryption to do a brief analysis.

Fig. 6-14 Schematic of asymmetric encryption

As shown in Figure 6-14, two keys, a public key, a private key, are prepared before the data is encrypted, and the public key is publicly available to anyone, and the private key is owned by the decryption party. The conversation between the two sides for Lao Li and Xiao Wang, Lao Li now want to give Xiao Wang transmission data, in order to avoid being monitored, Lao Li needs to encrypt the data. Because the data recipient is Xiao Li, so Lao Wang chose to use Xiao Li's public key to encrypt, Xiao Li's public key anyone can know, do not need secret transmission. After receiving the data transmitted by Lao Wang, Xiao Li decrypts it using only the private key he knows. From the view of the whole process, it does not involve the transmission of key, so the key transmission security problem of symmetric encryption is fundamentally solved.

Author: Hyun-Soul

Source: http://www.cnblogs.com/xuanhun/

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