1. A method of validating and authenticating a voter-marked paper ballot, the method comprising: calculating a unique authentication value based on election information provided on the voter-marked paper ballot; printing the authentication value on the voter-marked paper ballot as an encrypted security code in a printed security feature, the authentication value encrypted using a private-public key pair; associating the authentication value with a scanner that is configured to receive and scan ballots having been completed by voters; scanning each voter-completed ballot to obtain the encrypted security code from the voter-marked paper ballot; decrypting the encrypted security code using the private-public key pair to obtain the authentication value; comparing the authentication value obtained from the ballot with the authentication value associated with the scanner; and physically marking the voter-marked paper ballot as invalid when the ballot-obtained authentication value does not match the authentication value associated with the scanner.