RSA

package com.client.rsa;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.math.BigInteger;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.interfaces.RSAPrivateCrtKey;
import java.security.interfaces.RSAPublicKey;

import com.nettyServer.util.BaseString;
import com.nettyServer.util.ByteUtils;

public class RSAUtil {
    public String[] initGenKey(int keylen) {
        String[] genInfo = new String[5];
        try {
            KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
            kpg.initialize(keylen);
            KeyPair kp = kpg.generateKeyPair();
            RSAPublicKey puk = (RSAPublicKey) kp.getPublic();
            RSAPrivateCrtKey prk = (RSAPrivateCrtKey) kp.getPrivate();
            BigInteger e = puk.getPublicExponent();
            BigInteger n = puk.getModulus();
            log("n len(" + n.toByteArray().length + ")");
            BigInteger d = prk.getPrivateExponent();
            BigInteger p = prk.getPrimeP();
            BigInteger q = prk.getPrimeQ();
            genInfo[0] = e.toString();
            genInfo[1] = n.toString();
            genInfo[2] = d.toString();
            genInfo[3] = p.toString();
            genInfo[4] = q.toString();
            String[] des = { "e", "n", "d", "p", "q" };
            for (int i = 0; i < genInfo.length; i++) {
                log(des[i] + "=" + genInfo[i]);
            }
        } catch (NoSuchAlgorithmException ex) {
            ex.printStackTrace();
        }
        return genInfo;
    }

    //encrypt data
    public byte[] encrypt(byte[] ptext, String eStr, String nStr) throws IOException {
        log("*******************************encrypt start*************************************");
        BigInteger e = new BigInteger(eStr);//publickey param d
        BigInteger n = new BigInteger(nStr);//publickey param d
        int len = (n.toByteArray().length - 1), i = 0;
        int inputLen = ptext.length;
        BigInteger m = null;
        BigInteger c = null;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache=null;
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > len) {
                cache = new byte[len];
            } else {
                cache = new byte[inputLen - offSet];
            }
            System.arraycopy(ptext, offSet, cache, 0, cache.length);
            m = new BigInteger(cache);
            c = m.modPow(e, n);
            out.write(c.toByteArray());
            log("encrypt before:len(" + cache.length + "),data("+i+"):"
                    + ByteUtils.bytesToHexString(cache));
            log("encrypt after data("+i+"):"
                    + ByteUtils.bytesToHexString(c.toByteArray()));
            i++;
            offSet = i * len;
        }
        byte[] encryptData=out.toByteArray();
        out.close();
        log("*******************************encrypt end*************************************");
        return encryptData;
    }

    //decrypt data
    public byte[] decrypt(byte[] miwen, String dStr, String nStr) throws IOException {
        log("*******************************decrypt start*************************************");
        BigInteger d = new BigInteger(dStr);//privatekey param d
        BigInteger n = new BigInteger(nStr);//privatekey param n
        BigInteger c = null;
        BigInteger m = null;
        int len = n.toByteArray().length;
        int i = 0;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int inputLen = miwen.length;
        int offSet = 0;
        byte[] cache = null;
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > len) {
                cache = new byte[len];
            } else {
                cache = new byte[inputLen - offSet];
            }
            System.arraycopy(miwen, offSet, cache, 0, cache.length);
            c = new BigInteger(cache);
            m = c.modPow(d, n);
            byte[] dData = m.toByteArray();
            out.write(dData);
            log("decrypt before data("+i+"):"
                    + ByteUtils.bytesToHexString(cache));
            log("decrypt after:len(" + dData.length + "),data("+i+"):"
                    + ByteUtils.bytesToHexString(dData));
            i++;
            offSet = i * len;
        }
        byte[] entryDataB=out.toByteArray();
        out.close();
        log("*******************************decrypt end*************************************");
        return entryDataB;
    }
   
    private void log(String log){
        System.out.println(log);
    }

    public static void main(String[] args) throws IOException {
        RSAUtil rsaUtil = new RSAUtil();
        String[] p = rsaUtil.initGenKey(1023);// 1023
        //中文需要采用base编码后再加密
        String data = "18BB49FBC8AE1A82EECFECF8BB89C9D35FAAB857CC0C3B959DA3C3D513CAB255A0B627FDDE15813629A00FBF464740A32C7907B5B845245D9CDAC3F5F68A666EAFDE3FCE21A8096A61BABB659DDDB899F8CD29B2604199BC1F42993DFAB09ABFBE6BE69B7C299CBA6797EEE21665AF6B67A8061DBE6FA2EB0825C366DD812129";
        //String text = Base64.encodeBase64String(data.getBytes("GBK"));
        rsaUtil.log("(" + data.length() + ")" + data);
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        out.write(BaseString.getBytes(data));
        byte[] minwen = out.toByteArray();
        out.close();
        byte[] hex = rsaUtil.encrypt(minwen, p[0], p[1]);
        byte[] decodeData = rsaUtil.decrypt(hex, p[2], p[1]);
        data = BaseString.byteToString(decodeData);
        //data = BaseString.byteToString(Base64.decodeBase64(decodeData));
        rsaUtil.log("(" + data.length() + ")" + data);
    }
}

 

output:

n len(128)
e=65537
n=79878443116477431723910720076331964206927196983187460111829662096543709950682705577119366644900259032296548146226108881718640174009506648698055329399979826968504236032315385550029317396676828095359442971095598662249798287465446643154424521383364489258800969007909367639398542203155486245540834166630656463551
d=26360849103913421324209851744982341606534040562619259155876099483101871596401506877366032345024990499267737969491711291237175178654464040130636749687394346556715475310635822940069011833047004651164959543795626563240523875100964945568109834945618143409494207572709757223766144562392543175635168401408831807649
p=12388121363302700405059571893776373129179128456352582548743075852274073073044285422961339481772197365397373993998587373598128718142470712954759279729185579
q=6447986807192665658869257921655147348637730988762875266579286105565709187930397704433502779690215309166895026920782468729159257017248953918267942262113469
(256)18BB49FBC8AE1A82EECFECF8BB89C9D35FAAB857CC0C3B959DA3C3D513CAB255A0B627FDDE15813629A00FBF464740A32C7907B5B845245D9CDAC3F5F68A666EAFDE3FCE21A8096A61BABB659DDDB899F8CD29B2604199BC1F42993DFAB09ABFBE6BE69B7C299CBA6797EEE21665AF6B67A8061DBE6FA2EB0825C366DD812129
*******************************encrypt start*************************************
encrypt before:len(127),data(0):31384242343946424338414531413832454543464543463842423839433944333546414142383537434330433342393539444133433344353133434142323535413042363237464444453135383133363239413030464246343634373430413332433739303742354238343532343544394344414333463546363841363636
encrypt after data(0):0A393732881F8FD5347AC6EA5DD17D862567608038C39FDB57E0E0FCFA6C6BD2795FE9A7B52C9D60B57B70E867C692B907140A784C1C86E61E00E4CCBBC4541A83C97F7478C0F0A662066755A390022EB76ADA8948893564DF56524C58E47ACC672624C0EB9CE6822B703F69D851F9D68C84FB75D0A6636DE14E3A995AB38D3C
encrypt before:len(127),data(1):45414644453346434532314138303936413631424142423635394444444238393946384344323942323630343139394243314634323939334446414230394142464245364245363942374332393943424136373937454545323136363541463642363741383036314442453646413245423038323543333636444438313231
encrypt after data(1):48845A09A4FF5B012BBE42FC83F250B0AEA5D4FE1EA6A59BE813166C561EB1BA4F1744E79F50FC072016FF68384DCA1CA86B90BE50753956B9F1D5B68983F67C63EAF8ECFD62F1A6C3491469F6E6CFD8E895694678B2A24A9098FA120EF826C461B0ABF8B1B0C9E4EFD8E70547553068BA8560B61F7691E435E947E999A4B5C0
encrypt before:len(2),data(2):3239
encrypt after data(2):3D940F0A14DA5A9838AAF70049C978529569667BB5D3191A7075A3DA53205EA2C74E4F3CF21814514A45275246CBB579F9768ED321BFEAA8CCED6C6EA683DD866CB5660B513360799D69C4CF6BEBDCD0A1976510A6C6FF19E6A4915B85A5533FE5644E4CD761B0A37F3D19004685C52C8A931F074DE15D615DA88C3E98D99FD4
*******************************encrypt end*************************************
*******************************decrypt start*************************************
decrypt before data(0):0A393732881F8FD5347AC6EA5DD17D862567608038C39FDB57E0E0FCFA6C6BD2795FE9A7B52C9D60B57B70E867C692B907140A784C1C86E61E00E4CCBBC4541A83C97F7478C0F0A662066755A390022EB76ADA8948893564DF56524C58E47ACC672624C0EB9CE6822B703F69D851F9D68C84FB75D0A6636DE14E3A995AB38D3C
decrypt after:len(127),data(0):31384242343946424338414531413832454543464543463842423839433944333546414142383537434330433342393539444133433344353133434142323535413042363237464444453135383133363239413030464246343634373430413332433739303742354238343532343544394344414333463546363841363636
decrypt before data(1):48845A09A4FF5B012BBE42FC83F250B0AEA5D4FE1EA6A59BE813166C561EB1BA4F1744E79F50FC072016FF68384DCA1CA86B90BE50753956B9F1D5B68983F67C63EAF8ECFD62F1A6C3491469F6E6CFD8E895694678B2A24A9098FA120EF826C461B0ABF8B1B0C9E4EFD8E70547553068BA8560B61F7691E435E947E999A4B5C0
decrypt after:len(127),data(1):45414644453346434532314138303936413631424142423635394444444238393946384344323942323630343139394243314634323939334446414230394142464245364245363942374332393943424136373937454545323136363541463642363741383036314442453646413245423038323543333636444438313231
decrypt before data(2):3D940F0A14DA5A9838AAF70049C978529569667BB5D3191A7075A3DA53205EA2C74E4F3CF21814514A45275246CBB579F9768ED321BFEAA8CCED6C6EA683DD866CB5660B513360799D69C4CF6BEBDCD0A1976510A6C6FF19E6A4915B85A5533FE5644E4CD761B0A37F3D19004685C52C8A931F074DE15D615DA88C3E98D99FD4
decrypt after:len(2),data(2):3239
*******************************decrypt end*************************************
(256)18BB49FBC8AE1A82EECFECF8BB89C9D35FAAB857CC0C3B959DA3C3D513CAB255A0B627FDDE15813629A00FBF464740A32C7907B5B845245D9CDAC3F5F68A666EAFDE3FCE21A8096A61BABB659DDDB899F8CD29B2604199BC1F42993DFAB09ABFBE6BE69B7C299CBA6797EEE21665AF6B67A8061DBE6FA2EB0825C366DD812129