How can I compress or encrypt data on a CD-ROM?
(2003/01/13) The easiest way is to use your favorite compression or encryption utility and process the files before putting them on the CD. However, this isn’t transparent to the end user. CRI-X3 enables programs like DoubleSpace to work on a CD. It’s intended for a publisher or for significant internal use, and the licensing is priced accordingly. See http://www.cdrominc.com/. (Side note: the company filed patent infringement suits against Traxdata and CeQuadrat in Sep 1998 for distributing CD compression software. This might account for the dearth of similar applications.) A straightforward solution is to write all of the files onto the disc as .ZIP files, and then use ZipMagic (formerly ZipFolders) to view the contents. It can be found at http://www.ontrack.com/zipmagic/. PGP at http://www.nai.com/ (was http://www.pgp.com) has some good encryption software, but none of it seems directly applicable to software distribution. PGPdisk, available for the Mac, might be useful but it isn’t
(2002/12/09) The following was part of an e-mail message from Jeff Arnold back in mid-1997: “I do not recommend making “copies of copies” with SNAPSHOT. The reason this does not always work is because many CDROM readers do not perform error correction of the data when doing raw sectors reads. As a result, you end up with errors on the copy that may or may not be correctable. When you make a second-generation copy of the same disc, you will make a disc that has all of the errors of the first copy, plus all of the new errors from the second reading of the disc. The cumulative errors from multiple copies will result in a disc that is no longer readable.” This initially generated some confusion, so further explanation is needed. The heart of the problem is the way that that the data is read from the source device. When a program does “raw” sector reads, it gets the entire 2352-byte block, which includes the CD-ROM error correction data (ECC) for the sector. Instead of applying the ECC to t
