signaturedata.java

java写的文件加密算法

package com._21cn.cryptto; 
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.spec.PKCS8EncodedKeySpec;


public class SignatureData {


public void run() {
try { 
String prikeyvalue = "";//这是GenerateKeyPair输出的私钥编码
PKCS8EncodedKeySpec priPKCS8=new PKCS8EncodedKeySpec(hexStrToBytes(prikeyvalue)); 
KeyFactory keyf=KeyFactory.getInstance("RSA");
PrivateKey myprikey=keyf.generatePrivate(priPKCS8);

String myinfo = "orderId=10dkfadsfksdkssdkd&amount=80&orderTime=20060509"; // 要签名的信息
// 用私钥对信息生成数字签名
java.security.Signature signet = java.security.Signature
.getInstance("MD5withRSA");
signet.initSign(myprikey);
signet.update(myinfo.getBytes("ISO-8859-1"));
byte[] signed = signet.sign(); // 对信息的数字签名

System.out.println("signed(签名内容)原值=" + bytesToHexStr(signed));
System.out.println("info（原值）=" + myinfo);


System.out.println("签名并生成文件成功");
} catch (java.lang.Exception e) {
e.printStackTrace();
System.out.println("签名并生成文件失败");
}
;

}
/**
* Transform the specified byte into a Hex String form.
*/
public static final String bytesToHexStr(byte[] bcd) {
StringBuffer s = new StringBuffer(bcd.length * 2);

for (int i = 0; i < bcd.length; i++) {
s.append(bcdLookup[(bcd[i] >>> 4) & 0x0f]);
s.append(bcdLookup[bcd[i] & 0x0f]);
}

return s.toString();
}

/**
* Transform the specified Hex String into a byte array.
*/
public static final byte[] hexStrToBytes(String s) {
byte[] bytes;

bytes = new byte[s.length() / 2];

for (int i = 0; i < bytes.length; i++) {
bytes[i] = (byte) Integer.parseInt(s.substring(2 * i, 2 * i + 2),
16);
}

return bytes;
}

private static final char[] bcdLookup = { '0', '1', '2', '3', '4', '5',
'6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
SignatureData s = new SignatureData();
s.run();

}
}