Java 签名 initSign()方法，带示例
原文:https://www . geesforgeks . org/Java-signature-initsign-method-with-examples/
initSign(私钥)
java.security.Provider 类的 initSign() 方法用于初始化这个对象进行签名。如果使用不同的参数再次调用此方法，它会否定此调用的效果。
语法:
public final void
initSign(PrivateKey privateKey)
throws InvalidKeyException
参数:该方法将身份的私钥作为将要生成签名的参数 异常:该方法在密钥无效的情况下抛出 InvalidKeyException 。
以下是说明 initSign()方法的示例:
注意:以下程序不会在联机 IDE 中运行
例 1:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to demonstrate
// initSign() method
import java.security.*;
import java.util.*;
import sun.misc.BASE64Encoder;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// calling getKeyPair() method and assigning in keypair
KeyPair keyPair = getKeyPair();
// creating byte array object
byte[] outbuff = new byte[1000];
// data to be updated
byte[] data = "test".getBytes("UTF8");
// creating the object of Signature
Signature sr = Signature.getInstance("SHA1WithRSA");
// initializing the signature object with key pair
// for signing
// Using method initSign
sr.initSign(keyPair.getPrivate());
// updating the data
sr.update(data);
// getting the signature byte
// of an signing operation
// by using method sign()
byte[] bytes = sr.sign();
// printing the number of byte
System.out.println("Signature:" + Arrays.toString(bytes));
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (SignatureException e) {
System.out.println("Exception thrown : " + e);
}
}
// defining getKeyPair method
private static KeyPair getKeyPair() throws NoSuchAlgorithmException
{
// creating the object of KeyPairGenerator
KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
// initializing with 1024
kpg.initialize(1024);
// returning the key pairs
return kpg.genKeyPair();
}
}
输出:
Signature:[-109, -21, 90, -114, -22,
....
....
...., 92, 1]
示例 2: 显示无效关键异常
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to demonstrate
// initSign() method
import java.security.*;
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// data to be updated
byte[] data = "test".getBytes("UTF8");
// creating the object of Signature
Signature sr = Signature.getInstance("SHA1WithRSA");
// initializing the signature object with key pair
// for signing
// Using method initSign
System.out.println("Trying to put null as private key ");
sr.initSign(null);
// updating the data
sr.update(data);
// getting the signature byte
// of an signing operation
// by using method sign()
byte[] bytes = sr.sign();
// printing the number of byte
System.out.println("Signature:" + Arrays.toString(bytes));
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (SignatureException e) {
System.out.println("Exception thrown : " + e);
}
catch (InvalidKeyException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
Trying to put null as private key
Exception thrown : java.security.InvalidKeyException: Key must not be null
initSign(私钥，SecureRandom)
java.security.Provider 类的 initSign() 方法用于初始化这个对象进行签名。如果使用不同的参数再次调用此方法，它会否定此调用的效果。
语法:
public final void
initSign(PrivateKey privateKey, SecureRandom random)
throws InvalidKeyException
参数:该方法取以下参数:
- 私钥–将要生成签名的身份的私钥。
- 随机–该签名的随机来源。
异常:如果密钥无效，此方法抛出invaliddkeexception。
下面是举例说明 sign()方法的例子:
注意:以下程序不会在联机 IDE 中运行
例 1:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to demonstrate
// sign() method
import java.security.*;
import java.util.*;
import sun.misc.BASE64Encoder;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// calling getKeyPair() method and assigning in keypair
KeyPair keyPair = getKeyPair();
// creating byte array object
byte[] outbuff = new byte[1000];
// data to be updated
byte[] data = "test".getBytes("UTF8");
// creating the object of Signature
Signature sr = Signature.getInstance("SHA1WithRSA");
// creating the object of SecureRandom
SecureRandom sb = SecureRandom.getInstance("SHA1PRNG");
// initializing the signature object with key pair
// for signing
sr.initSign(keyPair.getPrivate(), sb);
// updating the data
sr.update(data);
// getting the signature byte
// of an signing operation
// by using method sign()
byte[] bytes = sr.sign();
// printing the number of byte
System.out.println("Signature:" + Arrays.toString(bytes));
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (SignatureException e) {
System.out.println("Exception thrown : " + e);
}
}
// defining getKeyPair method
private static KeyPair getKeyPair() throws NoSuchAlgorithmException
{
// creating the object of KeyPairGenerator
KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
// initializing with 1024
kpg.initialize(1024);
// returning the key pairs
return kpg.genKeyPair();
}
}
输出:
Signature:[-121, -82, ....
....
....104, 114, -67]
示例 2: 显示无效关键异常
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to demonstrate
// initSign() method
import java.security.*;
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// creating byte array object
byte[] outbuff = new byte[1000];
// data to be updated
byte[] data = "test".getBytes("UTF8");
// creating the object of Signature
Signature sr = Signature.getInstance("SHA1WithRSA");
// creating the object of SecureRandom
SecureRandom sb = SecureRandom.getInstance("SHA1PRNG");
// initializing the signature object with null key pair
// for signing using initSign() method
System.out.println("Trying to put the null as key");
sr.initSign(null, sb);
// updating the data
sr.update(data);
// getting the signature byte
// of an signing operation
// by using method sign()
byte[] bytes = sr.sign();
// printing the number of byte
System.out.println("Signature:" + Arrays.toString(bytes));
}
catch (NoSuchAlgorithmException e) {
System.out.println("Exception thrown : " + e);
}
catch (InvalidKeyException e) {
System.out.println("Exception thrown : " + e);
}
}
}
输出:
Trying to put the null as key
Exception thrown : java.security.InvalidKeyException: Key must not be null
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