How to Authenticate Data With Digital Signatures

Digital signatures identify the sender of documents and emails for security purposes. By using public-key cryptology, a code known as a private key is attached to messages sent electronically. Receivers open and read the message with a public key. They know that the data they receive is authentic; often more so than with paper signatures. Follow these steps to authenticate data with digital signatures.

Difficulty: Moderate

Instructions

1. Obtain a digital certificate from an authorized digital authenticity or certification authority such as Verisign, Thawte, GlobalSign or BT. You need a digital certificate to create a digital signature. The use of digital certificates for digital signatures is also known as Secure MIME (SMIME) standard.

2. Look to PGP technology as an alternative to SMIME. PGP uses digital signatures and encrypts mail to authenticate data. The receiver must use the same standard that you do, SMIME or PGP.

3. Compose your message first if you're using PGP. When finished, click the PGPtray icon. Select "Current Window-Sign" to choose an available key. Type in your password. Click "Next" to digitally sign and encrypt the message.

4. Open a new message window if you're using SMIME, and click "Digitally Sign" under the Tools menu.

5. Copy and paste your document in the message window or compose a new message for a SMIME digital signature.

6. Send your message in the usual way with either standard.

7. Decode messages if you are the receiver. If using PGP, the receiver will click on the "Decode and verify" tool. When this process is complete, PGP will display it in a secure message viewer. If the message was altered in any way, there will a message in the viewer window attesting to the lack of authenticity.

Tips & Warnings

• Automatically add the digital ID's to contacts in your Outlook Express Address Book by clicking on the Tools menu. Choose "Options," and then click the "Security" tab. Choose "Advanced," and check "Add senders' certificates to my address book."
• The Microsoft Outlook Express Digital ID Web site provides links for getting your digital ID.
• If using PGP standards, consider plug-ins for an even easier way to use digital signatures.
• Protect your key with a password or passphrase to prevent it from being stolen from your computer. You should also consider storing it apart from the computer you use it with.
• Many web-based and older email clients are not compatible with SMIME standards, but many web-based programs can use PGP technology.