2. In a public key cryptosystem, the encryption key (public key) PK is public information, while the decryption key (key) SK needs to be kept secret. An encryption algorithm e and a decryption algorithm d are also disclosed. Although the decryption key SK is determined by the public key PK, it cannot be calculated from PK.
3. Based on this theory, the famous RSA algorithm appears in 1978, which is usually a pair of RSA keys, one of which is a secret key and kept by the user; The other is the public key, which can be made public or even registered on the network server. In order to improve the security strength, RSA keys should be at least 500 bits long, and it is generally recommended to use 1024 bits. This makes the calculation of encryption very large.
4.RSA algorithm is the first algorithm that can be used for both encryption and digital signature, and it is also easy to understand and operate. RSA is the most widely studied public key algorithm. Over the past 30 years since it was put forward, it has withstood the test of various attacks and gradually been accepted by people. It is generally considered as one of the best public key schemes at present.
5. ssl3.0 and TSL 1.0 in commonly used https use RSA encryption keys, as well as digital certificates, digital signatures, digital signatures, digital watermarks and digital envelopes. For example, the U shield of the bank, the card reader of the bank card and the digital certificate of Taobao are all encrypted by RSA.