实现RSA算法的方法

一开始不知道有BigInteger这个大数类，居然自己去实现了一个，写了大数加法后，才发现有现成的T_T

package rsa;

import java.math.BigInteger;

public class RSA {

private long p,q,e,d,n;

public RSA(){

int pIndex = (int)(Math.random()*10);

int qIndex;

int eIndex;

do{

qIndex = (int)(Math.random()*10);

}

while(qIndex==pIndex);

do{

eIndex = (int)(Math.random()*10);

}

while(eIndex==pIndex||eIndex==pIndex);

p = 1033;

q = 2017;

e =29437;

n = p*q;

d = calculateD();

}

private long calculateD(){

long t0 = 0,t1 = 1,t2 = -1;

long r0 = (p-1)*(q-1), m = r0,r1 = e ,r2 = -1;

do{

long q = r0/r1;

r2 = r0-r1*q;

if(r2==0)break;

t2 = t0 - t1*q;

while(t2<0){

t2+=m;

}

if(t2>=m){

t2 %= m;

}

r0 = r1;

r1 = r2;

t0 = t1;

t1 = t2;

}while(r2!=0);

if(r1!=1){

return 0;

}

else{

return t2;

}

}

public long getE() {

return e;

}

public long getN() {

return n;

}

public long getD() {

return d;

}

public BigInteger encode(BigInteger data){

return pow(data,d).mod(new BigInteger(n+""));

}

public BigInteger decode(BigInteger code){

return pow(code,e).mod(new BigInteger(n+""));

}

public BigInteger pow(BigInteger data,long p){

data = data.pow((int)p);

return data;

}

public static void main(String args[]){

RSA rsa = new RSA();

BigInteger data = new BigInteger("222222");

long oldtime = System.currentTimeMillis();

BigInteger code = rsa.encode(data);

long newtime = System.currentTimeMillis();

double codetime = ((double)(newtime-oldtime))/1000;

oldtime = System.currentTimeMillis();

BigInteger decode = rsa.decode(code);

newtime = System.currentTimeMillis();

double decodetime = ((double)(newtime-oldtime))/1000;

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

System.out.println("publickKey:"+rsa.e);

System.out.println("N:"+rsa.n);

System.out.println("data:"+data);

System.out.println("code:"+code+" time:"+codetime);

System.out.println("decode:"+decode+" time:"+decodetime);

}

}

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