java处理加密文件---实现RSA算法

//BJTU 软件0404    import java.io.*;    public class Rsa   {      private int p=0;      private int q=0;      private long n=0;      private long m=0;            private long public_key=0;//公匙      private long private_key=0;//密匙            private long text=0;//明文      private long secretword=0;//密文      private long word=0;//解密后明文            //判断是否为素数      public boolean primenumber(long t)      {          long k=0;          k=(long)Math.sqrt((double)t);          boolean flag=true;          outer:for(int i=2;i<=k;i++)          {              if((t%i)==0)              {                  flag = false;                  break outer;              }          }          return flag;      }      //输入PQ      public void inputPQ()throws Exception      {          do{                  System.out.println("请输入素数p: ");                  BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));                  String br=stdin.readLine();                  this.p=Integer.parseInt(br);           }          while(!primenumber(this.p));          do{              System.out.println("请输入素数q: ");              BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));              String br=stdin.readLine();              this.q=Integer.parseInt(br);          }          while(!primenumber(this.q));          this.n=this.p*this.q;          this.m=(p-1)*(q-1);          System.out.println("这两个素数的乘积为p*q："+this.n);          System.out.println("所得的小于Ｎ并且与Ｎ互素的整数的个数为m=(p-1)(q-1)："+this.m);      }      //求最大公约数      public long gcd(long a,long b)      {          long gcd;          if(b==0)              gcd=a;          else              gcd=gcd(b,a%b);          System.out.println("gcd:"+gcd);          return gcd;                }      //输入公匙      public void getPublic_key()throws Exception      {          do{              System.out.println("请输入一个公钥的值，这个值要求小于m并且和m互质： ");              BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));              String br=stdin.readLine();              this.public_key=Long.parseLong(br);          }while((this.public_key >= this.m) || (this.gcd(this.m,this.public_key)!=1));          System.out.println("公钥为："+this.public_key);      }      //计算得到密匙      public void getPrivate_key()      {          long value=1;          outer:for(long i=1;;i++)          {              value=i*this.m+1;              System.out.println("value:  "+value);              if((value%this.public_key==0)&& (value/this.public_key < this.m))              {                  this.private_key=value/this.public_key;                  break outer;              }          }          System.out.println("产生的一个私钥为："+this.private_key);      }      //输入明文      public void getText()throws Exception      {          System.out.println("请输入明文：");          BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));          String br=stdin.readLine();          this.text=Long.parseLong(br);      }      //加密、解密计算      public long colum(long y,long n,long key)      {          long mul;          if(key==1)              mul=y%n;          else               mul=y*this.colum(y,n,key-1)%n;          return mul;      }            //加密后解密      public void pascolum()throws Exception      {          this.getText();          System.out.println("输入明文为: "+this.text);          //加密          this.secretword=this.colum(this.text,this.n,this.public_key);          System.out.println("所得的密文为："+this.secretword);          //解密          this.word=this.colum(this.secretword,this.n,this.private_key);          System.out.println("解密后所得的明文为："+this.word);                }      public static void main(String []args)throws Exception      {          Rsa t = new Rsa();          t.inputPQ();          t.getPublic_key();          t.getPrivate_key();          t.pascolum();      }    }