What is an MD-5 Checksum?
MD-5 stands for MessageDigest Algorithm 5; typically expressed as a 32-character hexadecimal number used for file security. The MD-5 checksums (in eCTDs) are provided in the eCTD backbone and used to check the integrity of the individual documents during validation. In theory, the MD-5 checksum generated for one document will be different if changes are made. Similarly, no two documents would have identical MD-5 checksums unless the documents themselves were identical. In other words, the MD-5 for a document before and after even a small change (to the same document) would be different. In eCTDs, if the calculated MD-5 during validation does not match the MD-5 listed in the eCTD backbone, the submission is not valid. Depending on how the eCTD submission is created, MD-5 Checksums may be automatically generated when documents change or they may have to be updated.
