Java encryption and decryption-DES symmetric encryption algorithm

Package COM. jadyer. util. codec; import Java. security. key; import Java. security. nosuchalgorithmexception; import javax. crypto. cipher; import javax. crypto. keygenerator; import javax. crypto. secretkey; import javax. crypto. secretkeyfactory; import javax. crypto. spec. deskeyspec; import Org. apache. commons. codec. binary. base64; /*** DES symmetric encryption algorithm * @ see ============================== ======================================================== ========================================================== =====* @ See symmetric encryption algorithm is used to encrypt and decrypt data. Use a key to encrypt the data, and use the same key to decrypt the data * @ see des is an algorithm proposed by the US National Institute of Standards. Since the data security of encryption and decryption is proportional to the key length, the 56-bit key of Des has formed a security risk * @ see and later improved the DES algorithm, with the Triple DES algorithm (also called desede or triple-DES ). The full name is TDEA: Triple Data Encryption Algorithm * @ see desede improves the DES algorithm's key length and the number of iterations, improved security strength * @ see. However, the desede algorithm processing speed is slow and the key computing time is long, the low encryption efficiency makes the development of symmetric encryption algorithms not optimistic * @ see ========================== ========================================================== ========================================================== ===========* @ see Java and bouncycastle support different DES algorithm data encryption, mainly reflected in the key length, working mode and filling mode * @ see java6 only supports 56-bit keys, while bouncycastle supports 64-bit keys, its official website is http://www.bouncy Castle.org/* @ see, even on the desede algorithm, bouncycastle's key length is also longer than Java's key length * @ see ==================== ========================================================== ========================================================== =========* @ see In addition, java APIs only provide three symmetric encryption algorithm key material implementation classes: Des, desede, and PBE * @ see ================== ========================================================== ========================================================== =====================* @ see more java encryption and decryption algorithm implementations, you can refer to this blog http :// Blog.csdn.net/kongqz/article/category/800296 * @ see ============================== ========================================================== =================================================================== */Public class descodec {// algorithm name public static final string key_algorithm = "des "; // algorithm name/encryption mode/filling mode // des has four working modes --> ECB: Electronic cryptographic mode, CBC: Encrypted group link mode, CFB: encryption feedback mode, ofB: output feedback mode public static final string cipher_algorithm = "des/ECB/pkcs5padding ";/*** Generate key */public static string initkey () throws nosuchalgorithmexception {keygenerator kg = keygenerator. getinstance (key_algorithm); // instantiate the key generator kg. init (56); // initialize the secret generator secretkey = kg. generatekey (); // generate the key return base64.encodebase64string (secretkey. getencoded (); // obtain the binary key encoding form}/*** convert key */Private Static key Tokey (byte [] key) throws exception {javaseyspec DKS = new javaseyspec (key); // instantiate the des key Sec Retkeyfactory keyfactory = secretkeyfactory. getinstance (key_algorithm); // instantiate the key factory secretkey = keyfactory. generatesecret (DKS); // generate the key return secretkey ;} /*** encrypt data ** @ Param data to be encrypted * @ Param key * @ return encrypted data */public static string encrypt (string data, string key) throws exception {key K = Tokey (base64.decodebase64 (key); // restore the Key Cipher cipher = cipher. getinstance (cipher_algorithm );// Instantiate the cipher object, which is used to complete the actual encryption operation cipher. init (cipher. encrypt_mode, k); // initialize the cipher object and set it to the encryption mode return base64.encodebase64string (cipher. dofinal (data. getbytes (); // performs the encryption operation. Encrypted results are usually transmitted in base64 encoding.}/***** decrypt data * @ Param data to be decrypted data * @ Param key * @ return decrypted data */Public static string decrypt (string data, string key) throws exception {key K = Tokey (base64.decodebase64 (key); cipher = cipher. getinstance (cipher_algorithm); cipher. init (cipher. decrypt_mode, k); // initialize the cipher object and set it to the decryption mode return new string (cipher. dofinal (base64.decodebase64 (data); // execute the decryption operation} public static void main (string [] ARGs) throws exception {string source = ""; system. out. println ("Original:" + source); string key = initkey (); system. out. println ("key:" + key); string encryptdata = encrypt (source, key); system. out. println ("encryption:" + encryptdata); string decryptdata = decrypt (encryptdata, key); system. out. println ("decryption:" + decryptdata );}}