Generating a Digital Signature

The GenSig program you are about to create will use the JDK Security API to generate keys and a digital signature for data using the private key and to export the public key and the signature to files. The application gets the data file name from the command line.

The following steps create the GenSig sample program.

1. Prepare Initial Program Structure

   Create a text file named GenSig.java. Type in the initial program structure (import statements, class name, main method, and so on).

2. Generate Public and Private Keys

   Generate a key pair (public key and private key). The private key is needed for signing the data. The public key will be used by the VerSig program for verifying the signature.

3. Sign the Data

   Get a Signature object and initialize it for signing. Supply it with the data to be signed, and generate the signature.

4. Save the Signature and the Public Key in Files

   Save the signature bytes in one file and the public key bytes in another.

5. Compile and Run the Program