DES3 and differences between notations

Question

I want to decrypt some DES3 encrypted messages from other aplication. The problem is, that ruby uses backslash notation, which looks like that:

\xE7B8\xCF\xFC\x9Fu\fkΖ\xB3\u001As\x93\xFF

and I'm receiving something like that:

6613E58F24183FC60B2BB1A2EE9DA61A

I now how to use encryption in ruby, but I have no idea how to deal when I got notation as above. Do I need to convert it somehow? Any help would be greatly appreciated.

`\xE7B8\xCF\xFC\x9Fu\fkΖ\xB3\u001As\x93\xFF` is a specification of character encoded data. This is not what you want, what you want is bytes. So you should use a hexadecimal decoder. — Maarten Bodewes, Jan 28 '13 at 17:59

ichigolas · Accepted Answer · 2013-01-28T21:12:58.843

1

String#unpack should do the job:

> str = "\xE7B8\xCF\xFC\x9Fu\fkΖ\xB3\u001As\x93\xFF" # Use double-quotes
=> "\xE7B8\xCF\xFC\x9Fu\fkΖ\xB3\u001As\x93\xFF"
> str.unpack('H*')
=> ["e74238cffc9f750c6bce96b31a7393ff"]

The inverse workaround would be:

> str = ["6613E58F24183FC60B2BB1A2EE9DA61A"]
> str.pack 'H*'
=> "f\x13\xE5\x8F$\x18?\xC6\v+\xB1\xA2\xEE\x9D\xA6\x1A"

edited Jan 28 '13 at 21:12

answered Jan 28 '13 at 14:24

ichigolas

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I would vote this up, but it seems to be the wrong way around, the question was to go from `e74238cffc9f750c6bce96b31a7393ff` to `\xE7B8\xCF\xFC\x9Fu\fkΖ\xB3\u001As\x93\xFF`. I do think however that the user should go from `6613E58F24183FC60B2BB1A2EE9DA61A` to an internal representation of a byte array / octet string. – Maarten Bodewes Jan 28 '13 at 19:14
Edited for the inverse case. Sincerely, I'm not a guru at encodings, just offering an option. – ichigolas Jan 28 '13 at 21:13

score 0 · Answer 2 · answered Jan 28 '13 at 14:13

0

First notation is a string representation of raw binary data. Second one - is hex-encoded data, i.e. each byte is represented as two hex chars.

answered Jan 28 '13 at 14:13

Nickolay Olshevsky

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I don't get how the first one is supposed to be read. Looks broken to me. – CodesInChaos Jan 28 '13 at 14:16
Thanks! Could you give me a hint, how to convert second one to first? – zachar Jan 28 '13 at 14:16
Does [this](http://stackoverflow.com/questions/7735005/convert-hex-chars-into-a-string-of-bits-python-or-ruby) answer? – loopbackbee Jan 28 '13 at 14:19
Check this question: http://stackoverflow.com/questions/862140/hex-to-binary-in-ruby – Nickolay Olshevsky Jan 28 '13 at 17:47
@CodesInChaos according to wikipedia \xnn is used to represent "a character with hexadecimal value nn . Trick is knowing the internal encoding (which is per string in ruby). Seems like a flawed method to me too. – Maarten Bodewes Jan 28 '13 at 17:56

DES3 and differences between notations

2 Answers2