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Forum Index : Microcontroller and PC projects : CMM2: XXTEA file encryption with 'spcrypt'
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thwill Guru  Joined: 16/09/2019 Location: United KingdomPosts: 4311 |
Hi folks, I'm not sure why you'd want to, but with 'spcrypt' you can do XXTEA/CBC/PKCS#7 encryption/decryption of files - or at least that's what I'm saying it does until someone who knows more about encryption can tell me otherwise. 400MHz Colour Maximite 2 MMBasic Version 5.07.00b33 Copyright 2011-2021 Geoff Graham Copyright 2016-2021 Peter Mather > *cd sptools/src/spcrypt > *spcrypt spcrypt: no command specified Usage *spcrypt [OPTION]... <command> "input file" ["output file"] Options: -p, --password=<password> Use <password> for encryption/decryption. If omitted then user will be prompted. --version Output version information and exit. Commands: decrypt Decrypt "input file" using XXTEA algorithm. encrypt Encrypt "input file" using XXTEA algorithm. md5 Calculate MD5 checksum for "input file". > *spcrypt md5 spcrypt.bas 7ed827543e2e6cbb3aa00c19562dcb76 OK > *spcrypt encrypt -p=wombat spcrypt.bas Overwrite existing 'spcrypt.bas.encrypt' [y|N] ? y Encrypting from 'spcrypt.bas' to 'spcrypt.bas.encrypt' ... OK > *spcrypt decrypt -p=wombat spcrypt.bas.encrypt Overwrite existing 'spcrypt.bas.encrypt.decrypt' [y|N] ? y Decrypting from 'spcrypt.bas.encrypt' to 'spcrypt.bas.encrypt.decrypt' ... OK spcrypt.zip Notes: 1. This above .zip contains a "flattened" version of the source with all the dependencies (and some other random stuff it doesn't depend on) inlined, if you want to read the code I'd check my github repo for the original source instead: - https://github.com/thwill1000/sptools/blob/develop-r1b3/src/spcrypt/spcrypt.bas - https://github.com/thwill1000/sptools/blob/develop-r1b3/src/splib/crypt.inc 2. 'spcrypt' uses a random initialisation vector, so if you encrypt the same file twice you get two different output files, both of which should decrypt to the original file. 3. Whilst almost certainly "better" than any adhoc encryption this isn't on a par with AES-256. I'm using MD5 to convert a password to a 128-bit key, which isn't particularly recommended (https://en.wikipedia.org/wiki/MD5) and XXTEA is also not the most secure (https://en.wikipedia.org/wiki/XXTEA). Best wishes, Tom Edited 2021-06-01 01:11 by thwill MMBasic for Linux, Game*Mite, CMM2 Welcome Tape, Creaky old text adventures |
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CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2170 |
or this... http://www.fruitoftheshed.com/MMBasic.RC4-Encryption-and-Decryption-Functions.ashx Edited 2021-06-01 05:32 by CaptainBoing |
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| thwill Guru Joined: 16/09/2019 Location: United KingdomPosts: 4311 |
Thanks Captain, Indeed, I was aware of this implementation and it is undoubtedly faster but I would have learnt a great deal less. It's an obsolete stream cipher as opposed to an obsolete block cipher and the implementation provided doesn't have quite the bells and whistles supplied by spcrypt. Best wishes, Tom MMBasic for Linux, Game*Mite, CMM2 Welcome Tape, Creaky old text adventures |
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