In this post, I am going to explain how to read the keystore file content as base 64 encoded string and write the base64 encoded string to a new key store file.
To demonstrate the application, let’s create a new keystore file by executing beow command.
keytool -genkey -keyalg RSA -keystore myKeystore.jks -keysize 2048
$keytool -genkey -keyalg RSA -keystore myKeystore.jks -keysize 2048
Enter keystore password:
Re-enter new password:
What is your first and last name?
[Unknown]: Ram
What is the name of your organizational unit?
[Unknown]: hr
What is the name of your organization?
[Unknown]: abcCorp
What is the name of your City or Locality?
[Unknown]: Bangalore
What is the name of your State or Province?
[Unknown]: Karnataka
What is the two-letter country code for this unit?
[Unknown]: IN
Is CN=Ram, OU=hr, O=abcCorp, L=Bangalore, ST=Karnataka, C=IN correct?
[no]: y
Generating 2,048 bit RSA key pair and self-signed certificate (SHA256withRSA) with a validity of 90 days
for: CN=Ram, OU=hr, O=abcCorp, L=Bangalore, ST=Karnataka, C=IN
$
Let’s print the content of keystore file.
$keytool -list -keystore myKeystore.jks
Enter keystore password:
Keystore type: PKCS12
Keystore provider: SUN
Your keystore contains 1 entry
mykey, 8 Feb 2023, PrivateKeyEntry,
Certificate fingerprint (SHA-256): 7E:2E:8F:1A:6F:94:FA:2A:41:80:0E:39:EA:11:52:2F:A1:64:C0:70:7D:5B:26:3C:39:8A:E6:50:B7:57:60:D6
Find the below working application.
FileUtil.java
package com.sample.app.util;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Base64;
public class FileUtil {
public static String readFileContentAsBase64EncodedString(String filePath)
throws FileNotFoundException, IOException {
byte[] byteContent = getByteArray(filePath);
byte[] encoded = Base64.getEncoder().encode(byteContent);
return new String(encoded);
}
public static void writeBase64EncodedStringToFile(final String filePath, final String encodedContent) {
if (encodedContent == null) {
throw new IllegalArgumentException("encodedContent is null");
}
byte[] decocedBytes = Base64.getDecoder().decode(encodedContent.getBytes());
writeToFile(filePath, decocedBytes);
}
public static boolean writeToFile(final String filePath, final byte[] content) {
if (filePath == null) {
throw new IllegalArgumentException("filePath is null");
}
if (content == null || content.length == 0) {
throw new IllegalArgumentException("content is null or empty");
}
try (FileOutputStream out = new FileOutputStream(filePath);) {
out.write(content);
} catch (Exception e) {
return false;
}
return true;
}
public static byte[] getByteArray(final String filePath) throws FileNotFoundException, IOException {
if (filePath == null) {
throw new IllegalArgumentException("filePath is null");
}
try (final FileInputStream fis = new FileInputStream(new File(filePath))) {
return getByteArray(fis);
}
}
/**
* Methods which are calling this method are responsible to close the
* InputStream.
*
* @param inputStream
* @return
* @throws IOException
*/
private static byte[] getByteArray(final InputStream inputStream) throws IOException {
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
int nRead;
byte[] data = new byte[16384];
try {
while ((nRead = inputStream.read(data, 0, data.length)) != -1) {
byteArrayOutputStream.write(data, 0, nRead);
}
} catch (IOException e) {
e.printStackTrace();
if (inputStream != null) {
inputStream.close();
}
}
return byteArrayOutputStream.toByteArray();
}
}
App.java
package com.sample.app;
import java.io.FileNotFoundException;
import java.io.IOException;
import com.sample.app.util.FileUtil;
public class App {
public static void main(String[] args) throws FileNotFoundException, IOException {
String filePath = "/Users/Shared/keystore/myKeystore.jks";
String encodedString = FileUtil.readFileContentAsBase64EncodedString(filePath);
System.out.println(encodedString);
String destinationFilePath = "/Users/Shared/keystore/myKeystore1.jks";
FileUtil.writeBase64EncodedStringToFile(destinationFilePath, encodedString);
}
}
Run the above application, you will see a file myKeystore1.jks file is created.
Let’s print the content of myKeystore1.jks file to confirm the same.
$keytool -list -keystore myKeystore1.jks
Enter keystore password:
Keystore type: PKCS12
Keystore provider: SUN
Your keystore contains 1 entry
mykey, 8 Feb 2023, PrivateKeyEntry,
Certificate fingerprint (SHA-256): 7E:2E:8F:1A:6F:94:FA:2A:41:80:0E:39:EA:11:52:2F:A1:64:C0:70:7D:5B:26:3C:39:8A:E6:50:B7:57:60:D6
