The classic digital Signature Algorithm-rsa

Records:

Public Abstract classRsacodersignature {Private Static FinalString Private_key = "Rsaprivate_key"; Private Static FinalString Public_key = "Rsapublic_key"; Private Static Final intKey_size = 512; Private Static FinalString key_algorithm = "RSA"; Private Static FinalString signature_algorithm = "Md5withrsa";  Public Static byte[] Getprivatekey (map<string, object> keyMap)throwsException {key key=(Key) keymap.get (Private_key); returnkey.getencoded (); }     Public Static byte[] Getpublickey (map<string, object> keyMap)throwsException {key key=(Key) keymap.get (Public_key); returnkey.getencoded (); }        /*** Production Public private key is saved to map *@return     * @throwsException*/     Public StaticMap<string, object> Initkey ()throwsException {Map<string, object> KeyMap =NewHashmap<string, object> (2); Keypairgenerator Keypaigen=keypairgenerator.getinstance (Key_algorithm);        Keypaigen.initialize (key_size); KeyPair pair=Keypaigen.generatekeypair (); Rsapublickey PublicKey=(Rsapublickey) pair.getpublic (); Rsaprivatekey Privatekey=(Rsaprivatekey) pair.getprivate ();        Keymap.put (Public_key, PublicKey);        Keymap.put (Private_key, Privatekey); returnKeyMap; }    /*** Digital signature production with private key, *@paramData *@paramPrivatekey *@return     * @throwsException*/     Public Static byte[] Sign (byte[] Data,byte[] privatekey)throwsException {pkcs8encodedkeyspec PKC=NewPkcs8encodedkeyspec (Privatekey); Keyfactory keyfactory=keyfactory.getinstance (Key_algorithm); Privatekey Prikey=keyfactory.generateprivate (PKC); Signature Sig=signature.getinstance (Signature_algorithm);        Sig.initsign (Prikey);        Sig.update (data); returnsig.sign (); }        /*** Verify the correctness of the private key encryption with the public key decryption, *@paramData *@paramPublicKey *@paramSigns encryption digital certificate for private key production *@return     * @throwsException*/     Public Static BooleanVerifybyte[] Data,byte[] PublicKey,byte[] signs)throwsException {x509encodedkeyspec PKC=NewX509encodedkeyspec (PublicKey); Keyfactory keyfactory=keyfactory.getinstance (Key_algorithm); PublicKey PubKey=keyfactory.generatepublic (PKC); Signature Sig=signature.getinstance (Signature_algorithm);        Sig.initverify (PubKey);        Sig.update (data); returnsig.verify (signs); }}

The classic digital Signature Algorithm-rsa