A verification system randomly retrieves data from a removable data storage medium. The retrieved data is compared to corresponding verification data, which is known to be valid. The system determines that a legitimate removable data storage medium is present if the retrieved data matches the corresponding verification data. The removable data storage medium can be partitioned into multiple blocks of data. A cryptographic digest is calculated for each data block. The digests are compared to determine whether the retrieved data matches the verification data. The removable data storage medium may be a compact disc (CD) or a digital versatile disc (DVD).