The Java TM Tutorial

| Start of Tutorial > Start of Trail > Start of Lesson | Search

Trail: Security in JDK 1.1
Lesson: Using the Security API to Generate and Verify a Signature

## Step 1: Prepare Initial Program Structure

> To start the creation of our example application:
> 1. Create a text file named `testSig.java`.

> 2. Add `import` statements.

>    The methods for signing data are in the `java.security` package, so we import everything from that package. We also need to import the `java.io` package since it contains the methods we need to input the file data to be signed.

>        import java.io.*;
>        import java.security.*;

> 3. Start the class definition:

>        class testSig {

> 4. Type the signature for the `main` method (which we need, since this is an application), and write a comment about what this program does:

>            public static void main(String[] args) {

>                /* Test generating and verifying a DSA signature */

> 5. Write the exception-handling blocks.

>    These are needed because many methods called by the program throw exceptions that we must catch. Note: The code we write in subsequent steps of this lesson to generate and verify a signature will go between the `try` and `catch` blocks.

>                try {

>                } catch (Exception e) {
>                    System.err.println("Caught exception " + e.toString());
>                }

> 6. Write the closing braces for the main method and the testSig class:

>            }

>        }

> What We've Got So Far

> Now we've got the basic structure of our program. It looks like this:

>     import java.io.*;
>     import java.security.*;

>     class testSig {

>         public static void main(String[] args) {

>             /* Test generating and verifying a DSA signature */

>             try {

>             } catch (Exception e) {
>                 System.err.println("Caught exception " + e.toString());
>             }
>         }

>     }

| Start of Tutorial > Start of Trail > Start of Lesson | Search