The Java TM Tutorial

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Trail: Security in JDK 1.2
Lesson: Generating and Verifying Signatures

## Prepare Initial Program Structure

> Here's the basic structure of the `GenSig` program. Place it in a file called `GenSig.java`.

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

>     class GenSig {

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

>             /* Generate a DSA signature */

>             if (args.length != 1) {
>                 System.out.println("Usage: GenSig nameOfFileToSign");
>                 }
>             else try {

>             // the rest of the code goes here

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

>     }

> Notes:
> - The methods for signing data are in the `java.security` package, so the program imports everything from that package. The program also imports the `java.io` package, which contains the methods needed to input the file data to be signed.

> - A single argument is expected, specifying the data file to be signed.

> - The code written in subsequent steps will go between the `try` and the `catch` blocks.

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