Storage and loading of key pairs

Load is primarily used for digital signatures:





1. Storage Key Pair





first uses keypairgeneration to generate the key pair:





keypairgenerator keyGen = keypairgenerator.getinstance ("RSA");


keygen.initialize (1024);


KeyPair KeyPair = Keygen.genkeypair ();


Privatekey = Keypair.getprivate ();


PublicKey = Keypair.getpublic ();











how to store a key as a file:





FileOutputStream fs = new FileOutputStream (fileName);


Fs.write (privatekey.getencoded ());


Fs.close ();





2. Load Key pair





assumes that the public key file is Public.dat, Private.dat





first read the public key file:





//read Public Key


FileInputStream Fspublickey = new FileInputStream (publickeyfile);


Bufferedinputstream Bfspublickey = new Bufferedinputstream (Fspublickey);


byte[] Bytepublickey = new byte[bfspublickey.available ()];


Bfspublickey.read (Bytepublickey);


Bfspublickey.close ();





uses Keyfactory to generate a public key





//build Public Key


X509encodedkeyspec pubkeyspec = new X509encodedkeyspec (


Byteencodedpublickey);


keyfactory keyfactory = keyfactory.getinstance ("RSA");


PublicKey PubKey = Keyfactory.generatepublic (Pubkeyspec);











idea, the private key's processing and the public key is same, the only difference is the private key keyspec different. The private key should use Pkcs8encodedkeyspec