EAC - Voluntary Voting System Guidelines

Name : | Hank Dietz
Organization : | University of Kentucky
Post Date : | 9/30/2005
Section Comments
Section : | 6.4.4.5
Page no. : | 11
Line no.: | 24
Comment : | The use of "write-once" here and throughout this document is intended to mean "unalterable storage". It would be appropriate to define and use "unalterable storage" as write-once media that once written shall not contain "blank" writeable blocks and shall incorporate appropriate checksums or other mechanisms that make attempts to overwrite data ineffective or detectable with high probability. Discussion: For example, a CD-R is write-once media, but unless the entire CD-R is written (often called "finalizing" the CD-R) the blank portion can have data added to it at a later time. Even once a CD-R has been finalized or a PROM filled, it typically is still possible to change the values of bits -- but only in one direction. For example, a "blank" PROM might have all bits 1 and writing selectively makes some 0; however, unless there is an internal write-enabling fuse that can be deliberately blown, it is usually possible to convert other 1 bits into 0 bits at a later date. However, given appropriate checksums, it becomes very difficult to corrupt data in this way without the corruption being detectable by examining the checksum.