Appendix A Command-Line Demos 333
Command-Line Demo User’s Guide
Once a key pair has been generated, the following top-level menu is displayed:
S - Sign a file using DSA/SHA
V - Verify a DSA signed file
Q - Quit
Enter choice:
Commands may be entered in either upper or lower case, and all but the initial letter
of a command is ignored. So, for example, to sign a file you may either type “s” or
“sign”.
The commands on this top-level menu are described below.
Sign a File
To sign a file:
1. Enter s.
2. You will be prompted in succession for:
•the name and location of the file to be signed
•the name of the file that will hold the signature
3. BDEMODSA uses the private key generated at the beginning of the session to
create a signature and places the result in the specified file.
Verify a Signed File
To verify the signature for a file:
1. Enter v.
2. You will be prompted in succession for:
•the name and location of the file that was signed
•the name and location of the file containing the digital signature
3. BDEMODSA uses the public key generated at the beginning of the session to
verify the signature. If the signature is valid, BDEMODSA prints “Signature
verified.”; otherwise, BDEMODSA prints “ERROR: Invalid signature
while verifying file.”
Note: If the signature was generated during a previous execution of BDEMODSA, it
is necessary to re-use the seed from signature signing, otherwise verification
will fail.