In our actual use, encryption is an important means to ensure data security. In the past, when using ASP, the MD5 and SHA1 algorithms could be used to encrypt data. Although these two algorithms are fast and effective, they cannot inversely operate the ciphertext encrypted through them, that is, decryption. Therefore, when decrypting data, these two methods are not suitable. Of course, you can also write applicable encryption and decryption programs yourself, but this has high requirements for the writer's mathematical level, which is difficult for ordinary people to do.
Now, with the launch, the programming model under the previous ASP has been completely changed. We can use the encryption services provided by classes in the .Net Framework to ensure data security. The encryption method that is widely used at present is to use RSA algorithm for encryption. There are two main classes related to RSA encryption algorithm in the .Net Framework: RSA class and RSACryptoServiceProvider class. According to MSDN, the RSA class is "a base class that indicates that all implementations of the RSA algorithm are inherited from", while the RSACryptoServiceProvider class is "to perform asymmetric encryption and decryption using the implementation of the RSA algorithm provided by the CryptoService Provider (CSP)." In addition, the RSAParameters structure of "representing standard parameters of the RSA algorithm" is also very important, which saves the parameters of the RSA algorithm.
Since there are many articles or books introducing the principles of RSA algorithms, you can refer to them and will not repeat them here. The following is a highlight of how to implement RSA encryption in it.
Generation of RSA parameters: The type of RSA parameters is the RSAParameters structure mentioned above. Looking at MSDN, you can see that it contains eight fields: D, DP, DQ, Exponent, InverseQ, Modulus, P, and Q. When encrypting, only two values of Exponent and Modulus are required, which can be regarded as public keys. All fields are required during decryption and can be regarded as private keys. The following program shows how to generate two parameters of RSA:
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
RSAParameters rsaParamsExcludePrivate=(false);
RSAParameters rsaParamsIncludePrivate=(true);
The ExportParameters(bool) method of the RSACryptoServiceProvider class is used to export RSA parameters. True means exporting the "private key" of the above eight fields, and false means exporting the "public key".
Use RSA parameters for encryption and decryption: This step requires importing the above two parameters into the RSACryptoServiceProvider class object, and then encrypting the data. As shown in the following code, we can write a function to complete the encryption process:
Public byte [ ] RSAEncrypt ( byte [ ] b)
{
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
(rsaParamsExcludePrivate); //Import the public key
byte [] EncryptedData=(DataToEncrypt,false);
return EncryptedData;
}
When decrypting, just change (rsaParamsExcludePrivate) to (rsaParamsExcludePrivate), and then change Encrypt to Decrypt.
Save and load RSA parameters: RSA parameters can be saved in XML format. The following code explains how to save and load (only key parts are listed)
save:
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
StreamWriter writer=new StreamWriter(@"d:\");
string PPKeyXml=(true);//Save the private key (PPKeyXml);
();
writer=new StreamWriter(@"d:\");
string PKeyXml=(false);//Save the public key
(PKeyXml);
();
Read:
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
StreamReader reader=new StreamReader(@"d:\");
string PKey=();
(PKey);
();
StreamReader reader=new StreamReader(@"d:\");
string PPKey=();
();
ToXmlString is similar to ExportParameters methods. False means saving the "public key" and true means saving the "private key".