JAVA Asymmetric Encryption algorithm RSA

Asymmetric encryption algorithm RSA process: A case of both sides of A and B
1. Initialize key building key pair, generate public key, save private key to Keymap
Keypairgenerator--->keypair-->rsapublickey, rsaprivatekey
2, party a use private key encryption, after encryption in the private key to the encryption data signature, and then sent to party B
Rsacoder.encryptbyprivatekey (data, Privatekey);
Rsacoder.sign (Encodeddata, Privatekey);
3, the party B verifies the signed encrypted data through the public key, if the authentication is correct, decrypts the encrypted data through the public key
Rsacoder.verify (Encodeddata, PublicKey, sign);
Rsacoder.decryptbypublickey (Encodeddata, PublicKey);
4. Party B is sent to party A through public key encryption
Rsacoder.encryptbypublickey (Decodeddata, PublicKey);
5, the party to decrypt the data through the private key
Rsacoder.decryptprivatekey (Encodeddata, Privatekey);
The flowchart is as follows:

The Java code is implemented as follows:

Package Com.bank.utils;import Java.security.messagedigest;import Javax.crypto.keygenerator;import Javax.crypto.Mac ; Import Javax.crypto.secretkey;import Javax.crypto.spec.secretkeyspec;import Sun.misc.base64decoder;import Sun.misc.base64encoder;public Abstract class Coder {public static final string Key_sha = "SHA";p ublic static final string       KEY_MD5 = "MD5";/** * mac algorithm can choose the following algorithms * * <pre> * HmacMD5 * HmacSHA1 * HmacSHA256 * HmacSHA384 * HmacSHA512 * </pre> * * public static final String Key_mac = "HmacMD5";/** * BASE6 4 decryption * @param key * @return * @throws Exception */public static byte[] decryptBASE64 (String key) throws Exception{return (New Base64decoder ()). Decodebuffer (key);} /** * BASE64 Encryption * @param key * @return * @throws Exception */public static String encryptBASE64 (byte[] key) throws Excepti On{return (New Base64encoder ()). Encodebuffer (key);} /** * MD5 Encryption * @param data * @return * @throws Exception */public static byte[] encryptMD5 (byte[] data) throws Exception {messagedigest MD5 = messagedigest.getinstance (KEY_MD5); md5.update (data); return Md5.digest ();} /** * SHA Encryption * @param data * @return * @throws Exception */public static byte[] Encryptsha (byte[) data) throws Exception {MessageDigest sha = messagedigest.getinstance (Key_sha); sha.update (data); return Sha.digest ();} /** * Initialize HMAC key * * @return * @throws Exception */public static String Initmackey () throws Exc Eption{keygenerator keygenerator = keygenerator.getinstance (KEY_MAC); Secretkey Secretkey = Keygenerator.generatekey (); return encryptBASE64 (secretkey.getencoded ());} /** * HMAC Encryption * @param data * @param key * @return * @throws Exception */public static byte[] Encrypthmac (byte[) data, S Tring key) throws Exception{secretkey Secretkey = new Secretkeyspec (decryptBASE64 (key), KEY_MAC); Mac Mac = Mac.getinstance (Secretkey.getalgorithm ()); Mac.init (Secretkey); return mac.dofinal (data);}}

Package Com.bank.utils;import Java.security.key;import Java.security.keyfactory;import Java.security.KeyPair; Import Java.security.keypairgenerator;import Java.security.privatekey;import Java.security.publickey;import Java.security.signature;import Java.security.interfaces.rsaprivatekey;import Java.security.interfaces.rsapublickey;import Java.security.spec.pkcs8encodedkeyspec;import Java.security.spec.x509encodedkeyspec;import Java.util.hashmap;import Java.util.map;import Javax.crypto.Cipher; Public abstract class Rsacoder extends Coder{public static final string key_algorithm = "RSA";p ublic static final string S Ignature_algorithm = "Md5withrsa";p rivate static final String public_key = "Rsapublickey";p rivate static final string PRIV Ate_key = "Rsaprivatekey";/** * Digitally sign information with private key * @param data encrypted * @param privatekey private key * @return * @throws Exception */pub Lic static string sign (byte[] data, String privatekey) throws Exception {//Decrypt the private key base64 encoded by byte[] keybytes = decryptBASE64 (P Rivatekey); PKCS8Encodedkeyspec Pkcs8encodedkeyspec = new Pkcs8encodedkeyspec (keybytes); Keyfactory keyfactory = keyfactory.getinstance (key_algorithm);//Take private Key object Privatekey PKey = Keyfactory.generateprivate ( PKCS8ENCODEDKEYSPEC);//Generate a digital signature with the private key signature signature = Signature.getinstance (signature_algorithm); Signature.initsign (PKey); signature.update (data); return encryptBASE64 (Signature.sign ());} /** * Verify Digital signature * @param data encryption * @param publickey Public key * @param sign Digital signature * @return * @throws Exception */public Static Boo Lean verify (byte[] data, string publickey, String sign) throws exception{//decrypt the public key base64 encoded byte[] Keybytes = decryptBASE64 ( PublicKey); X509encodedkeyspec KeySpec = new X509encodedkeyspec (keybytes); Keyfactory keyfactory = keyfactory.getinstance (key_algorithm);//Take public key object PublicKey PKey = Keyfactory.generatepublic ( KEYSPEC); Signature Signature = signature.getinstance (signature_algorithm); signature.initverify (PKey); Signature.update (data );//Verify that the signature is normal return signature.verify (decryptBASE64 (sign));} /** * decryption * decryption with private key * @pAram Data Encryption * @param key * @return * @throws Exception */public static byte[] Decryptprivatekey (byte[] data, String key ) throws exception{byte[] Keybytes = decryptBASE64 (key);//Get private key pkcs8encodedkeyspec Encodedkeyspec = new Pkcs8encodedkeyspec (keybytes); Keyfactory factory = keyfactory.getinstance (Key_algorithm); Key PKey = factory.generateprivate (ENCODEDKEYSPEC);//decryption of data cipher cipher = Cipher.getinstance (Factory.getalgorithm ()) ; Cipher.init (Cipher.decrypt_mode, PKey); return cipher.dofinal (data);} /** * Decrypted with public key * @param data * @param key * @return * @throws Exception */public static byte[] Decryptbypublickey (byte[] Dat A, String key) throws exception{//decryption byte[] keybytes = decryptBASE64 (key);//Get public key x509encodedkeyspec KeySpec = new X509encod Edkeyspec (keybytes); Keyfactory keyfactory = keyfactory.getinstance (key_algorithm); Key PKey = Keyfactory.generatepublic (KEYSPEC);//decryption of data cipher cipher = Cipher.getinstance (Keyfactory.getalgorithm ()); Cipher.init (Cipher.decrypt_mode, PKey); return cipher.dofinal (data);} /** * Encrypted with public key * @param data * @param key * @return * @throws Exception */public static byte[] Encryptbypublickey (byte[] Dat A, String key) throws exception{byte[] Keybytes = decryptBASE64 (key); X509encodedkeyspec KeySpec = new X509encodedkeyspec (keybytes); Keyfactory keyfactory = keyfactory.getinstance (key_algorithm); Key PKey = Keyfactory.generatepublic (KeySpec); Cipher Cipher = cipher.getinstance (Keyfactory.getalgorithm ()); Cipher.init (Cipher.encrypt_mode, PKey); return Cipher.dofinal (data);} /** * Encrypted with private key * @param data * @param key * @return * @throws Exception */public static byte[] Encryptbyprivatekey (byte[] Dat A, String key) throws exception{byte[] Keybytes = decryptBASE64 (key); Pkcs8encodedkeyspec KeySpec = new Pkcs8encodedkeyspec (keybytes); Keyfactory keyfactory = keyfactory.getinstance (key_algorithm); Key Privatekey = keyfactory.generateprivate (KeySpec); Cipher Cipher = cipher.getinstance (Keyfactory.getalgorithm ()); Cipher.init (Cipher.encrypt_mode, Privatekey); return Cipher.dofinal (DATa);} /** * Get the private key * @param keyMap * @return * @throws Exception */public static String Getprivatekey (map<string, object> K Eymap) throws Exception{key Key = (key) keymap.get (Private_key); return encryptBASE64 (key.getencoded ());} /** * Get Public key * @param keyMap * @return * @throws Exception */public static String Getpublickey (map<string, object> ke YMAP) throws Exception{key Key = (key) keymap.get (Public_key); return encryptBASE64 (key.getencoded ());} /** * Initialize key * @return * @throws Exception */public static map<string, object> Initkey () throws Exception{keypairgene Rator keypairgenerator = keypairgenerator.getinstance (key_algorithm); keypairgenerator.initialize (1024); KeyPair KeyPair = Keypairgenerator.generatekeypair ();//Public key Rsapublickey PublicKey = (rsapublickey) keypair.getpublic () ;//private key Rsaprivatekey Privatekey = (rsaprivatekey) keypair.getprivate (); map<string, object> keyMap = new hashmap<string, object> (2); Keymap.put (Private_key, Privatekey); Keymap.put (Public_key, PubliCkey); return keyMap;}} 

Package Com.bank.test;import Java.util.map;import org.junit.assert;import org.junit.before;import org.junit.Test; Import Com.bank.utils.rsacoder;public class Rsacodertest {private string publickey;private string privatekey;/* * Asymmetric encryption algorithm RSA process: Take the two sides as an example * 1, initialize key building key pair, generate public key, private key saved to Keymap * keypairgenerator--->keypair-->rsapublickey, rsaprivat EKey * 2, party A uses the private key encryption, after encryption in the private key to encrypt the data to sign data, and then sent to party B * Rsacoder.encryptbyprivatekey (data, Privatekey); * Rsacoder.sign (Encodeddata, Privatekey); * 3, the party B verifies the signed encrypted data through the public key, if the authentication is correct, the encrypted data is decrypted by the public key * Rsacoder.verify (Encodeddata, PublicKey, sign); * Rsacoder.decryptbypublickey (Encodeddata, PublicKey); * * 4, Party B in the public key encryption sent to party A * Rsacoder.encryptbypublickey (Decodeddata, PublicKey); * 5, the party to decrypt the data by private key * Rsacoder.decryptprivatekey (Encodeddata, Privatekey); */@Beforepublic void SetUp () throws Exception {map<string, object> keyMap = Rsacoder.initkey ();p Ublickey = Rsacoder . Getpublickey (KEYMAP);p Rivatekey = Rsacoder.getprivatekey (KEYMAP); SYSTEM.OUT.PRINTLN ("Public key: \ n" + PUBlickey); SYSTEM.OUT.PRINTLN ("private key: \ n" + Privatekey);} @Testpublic void Test () throws exception{string inputstr = "abc"; byte[] data = Inputstr.getbytes ();//The resulting byte array is not the same each time. Second step private key encryption byte[] Encodeddata = Rsacoder.encryptbyprivatekey (data, privatekey);//private key for data signing string sign = Rsacoder.sign ( Encodeddata, Privatekey);//Third Step public key authentication Digital Signature Boolean flag = Rsacoder.verify (Encodeddata, PublicKey, sign); System.out.println ("flag:" + flag);//Decrypt data with public key byte[] Decodeddata = Rsacoder.decryptbypublickey (Encodeddata, PublicKey ); SYSTEM.OUT.PRINTLN ("Data:" + data + "Encrypt": "+ Encodeddata +" Decrypt data: "+ decodeddata); System.out.println ("Pre-encryption data-:" + new String (data) + "decrypted" + new string (Decodeddata));//Fourth step using public key to encrypt data Encodeddata = RSA Coder.encryptbypublickey (Decodeddata, PublicKey);//The fifth step uses the private key to decrypt the data Decodeddata = Rsacoder.decryptprivatekey ( Encodeddata, Privatekey); SYSTEM.OUT.PRINTLN ("Data:" + data + "Encrypt": "+ Encodeddata +" Decrypt data: "+ decodeddata); System.out.println ("Pre-encryption Data:" + INPUTSTR + "decrypted data:" + new String (decoDeddata));} @Testpublic void Test1 () throws Exception{system.out.println ("private key encryption-----Public key decryption"); String INPUTSTR = "abc"; byte[] data = Inputstr.getbytes (); SYSTEM.OUT.PRINTLN ("Data:" + data); byte[] Encodeddata = Rsacoder.encryptbyprivatekey (data, Privatekey); byte[] Decodeddata = Rsacoder.decryptbypublickey (Encodeddata, PublicKey); String outputstr = new string (decodeddata); System.out.println ("Before encryption:" + inputstr + "\ n decrypted:" + outputstr); Assert.assertequals (Inputstr, OUTPUTSTR); SYSTEM.OUT.PRINTLN ("Private key signature---Public key authentication signature");//generate signature String sign = Rsacoder.sign (Encodeddata, Privatekey); System.out.println ("signature: \ r" + sign);//Verify signature Boolean flag = Rsacoder.verify (Encodeddata, PublicKey, sign); System.out.println ("Status: \ r" + flag); Assert.asserttrue (flag);}}

　　

JAVA Asymmetric Encryption algorithm RSA