Convert a string of 0-F into a byte array in Ruby

Question

I am attempting to decrypt a number encrypted by another program that uses the BouncyCastle library for Java.

In Java, I can set the key like this: key = Hex.decode("5F3B603AFCE22359");

I am trying to figure out how to represent that same step in Ruby.

Nakilon · Accepted Answer · 2022-11-22 20:49:59Z

41

To get Integer — just str.hex. You may get byte array in several ways:

str.scan(/../).map(&:hex)
[str].pack('H*').unpack('C*')
[str].pack('H*').bytes.to_a

See other options for pack/unpack and examples (by codeweblog).

edited Nov 22, 2022 at 20:49

answered Sep 22, 2010 at 18:24

Nakilon

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1 Comment

Cadoiz Over a year ago

Isn't the .to_a superfluous? If someone cares about performance with huge Strings (10M hex digits): str.scan(/../).map(&:hex): 1.061567s, [str].pack('H*').unpack('C*'): 0.175744s [str].pack('H*').bytes.to_a: 0.149195s

ReWrite · Accepted Answer · 2014-10-06 22:36:13Z

3

For a string str:

"".tap {|binary| str.scan(/../) {|hn| binary << hn.to_i(16).chr}}

answered Oct 6, 2014 at 22:36

ReWrite

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2 Comments

Brandon Yarbrough Over a year ago

Nice! It's a style thing, but personally I'd rephrase it as: str.scan(/../).inject(""){|binary,hn| binary << hn.to_i(16).chr}.

Cadoiz Over a year ago

Note: str.scan(/../) performs way worse. This might be irrelevant for 'normal' numbers as of 1-16 bytes

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