java处理加密文件---RSA加密和解密

public class RSA {
public static void main(String []args)throws Exception
{
String ptext = "he";
//获取公钥生成参数
KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
kpg.initialize(1024);
KeyPair keyPair = kpg.genKeyPair();

RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();

System.out.println("公共码"+publicKey.getModulus().toString());

byte[] ptexts = ptext.getBytes("UTF8");
BigInteger m = new BigInteger(ptexts);
BigInteger c = m.modPow(publicKey.getPublicExponent(), publicKey.getModulus());
System.out.println("密文"+c);

//System.out.println("d："+privateKey.getPrivateExponent());

System.out.println("私密码"+privateKey.getModulus());

BigInteger jm=c.modPow(privateKey.getPrivateExponent(), privateKey.getModulus());
System.out.println("解码数据"+jm);

byte[] mt =jm.toByteArray();

System.out.print("解码结果");
for(int i=0;i<mt.length;i++){
System.out.print((char)mt[i]);
}

}
}