Detailed explanation of encryption and decryption function implemented by Java based on DES symmetric encryption algorithm

This paper describes the encryption and decryption function of Java based on DES symmetric encryption algorithm. Share with you for your reference, as follows:

Introduction to DES encryption related classes:

The securerandom class is inherited from Java util. Random class

There are three types of constructors for securerandom, and the following two are examples:

Securerandom () constructs a secure random number generator (RNG) that implements the default random number algorithm.

Secure random (byte [] seed) constructs a secure random number generator (RNG) that implements the default random number algorithm.

The deskeyspec class is used to generate the secret key content of the secret key using the original secret key

Deskeyspec has two constructors:

Deskeyspec (byte [] key) creates a deskeyspec object and uses the first 8 bytes in the key as the key content of the des key.

Deskeyspec (byte [] key, int offset) creates a deskeyspec object, and uses the first 8 bytes of the key starting from and containing offset as the key content of the des-ede key.

Secretkeyfactory, a key factory, is used to convert a key (an opaque encryption key of type key) into a key specification (a transparent representation of the underlying key material), and vice versa. A secret key factory only operates on secret (symmetric) keys.

The secret key object, the secret key object, generates the secret key by calling the generatesecret (deskeyspec deskeyspace) method of the secret key factory

Cipher class provides cryptographic functions for encryption and decryption, and obtains the instance by calling cipher's getInstance ("des")

The cipher object calls the init () method to initialize the object. The specific parameters of the init () method depend on the specific situation, including encryption and decryption constants

Finally, the doFinal () method of Cipher is used to encrypt and decrypt.

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2、 Use org apache. commons. codec. binary. Base64 decodes and encodes

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Download: sun misc. BASE64Decoder 。 Download: Apache Base64 codec and decoder.

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