DCipher5/4
Dcipher5 Keyless Cryptographic Image Cipher for Filter Forge:
Video tutorial: DCipher5
DCipher5 Filter Forge file (.ffxml) and the above graphic zipped:
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Dcipher 4 Text only stand alone app:
Last updated in 2002
Free, keyless exchange, and flexible, privacy software
according to yahoo search results (2007):
keyless privacy software -hardware -entry free cipher
this may be among the few 'pure software' ciphers that can do what:
http://www.vectorsite.net/ttcode_10.html
say's can't be done:
"The actual scenario with the useful ciphers available was not like having a box that could be fitted with two padlocks. It was like Alice having a small box that could be padlocked, and Bob having a bigger box that could be padlocked as well. Alice could send her small locked box to Bob, who would be able to put it inside his own big box and lock it, but then Alice would have no access to her own locked box when she received Bob's box. This neat-sounding keyless exchange scheme broke down in the real world."
Minor discussion on the ecrypt.eu.org eSTREAM forum (June 2, 2008):
http://www.ecrypt.eu.org/stream/phorum/read.php?1,1223
one of the first versions available was online way back in June of 2001, fwiw:
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