According to John Gilmore, when the EFF published the book about the "Deep Crack" DES cracker hardware titled "Cracking DES: Secrets of Encryption Research, Wiretap Politics, and Chip Design" [1], the US Government would not allow them to publish the software source code on a floppy or CDROM along with the book, because the export control laws considered DES software in machine readable form to be a munition.
However, they figured out that First Amendment protected their free speech to the extent that they were allowed to publish human readable listings of their source code in the book, even though a floppy disk was right out.
So just for that book, they invented a machine readable easy-to-scan "paper floppy disk" system that printed hex checksums of each line in the left column (which coincidentally looked enough like line numbers that it flew under the radar unnoticed), so you could scan and OCR the source code and checksums from the book, then validate it against the checksums to correct all the scanning errors.
> "Cracking DES" has been published only in print because US export controls on encryption make it a crime to publish such information on the Internet, but the book is designed to be easy to scan into computers. (EFF is also sponsoring a lawsuit by Professor Daniel Bernstein to overturn the law and regulations that make Internet publication of such research results illegal. The case now rests with the Ninth Circuit Court of Appeals.) [2]
However, they figured out that First Amendment protected their free speech to the extent that they were allowed to publish human readable listings of their source code in the book, even though a floppy disk was right out.
So just for that book, they invented a machine readable easy-to-scan "paper floppy disk" system that printed hex checksums of each line in the left column (which coincidentally looked enough like line numbers that it flew under the radar unnoticed), so you could scan and OCR the source code and checksums from the book, then validate it against the checksums to correct all the scanning errors.
> "Cracking DES" has been published only in print because US export controls on encryption make it a crime to publish such information on the Internet, but the book is designed to be easy to scan into computers. (EFF is also sponsoring a lawsuit by Professor Daniel Bernstein to overturn the law and regulations that make Internet publication of such research results illegal. The case now rests with the Ninth Circuit Court of Appeals.) [2]
[1] https://w2.eff.org/Privacy/Crypto/Crypto_misc/DESCracker
[2] http://www.oreilly.com/pub/pr/584