Digital signatures provide assurance of the identities of parties to electronic messages. Digital signatures are accomplished by encrypting an electronic message with a private encryption key, kept secret by the owner. Verifying a digital signature involves decrypting the encrypted data using a related public encryption key.
The quality that digital signatures provide is known as nonrepudiation. A digital signature enables a pharmacist to verify that the prescription has not been intentionally or accidentally altered during transmission. This is known as "message integrity."
Certificates are digitally signed electronic documents held by a certification authority that can attest to the legitimacy of the public encryption key.