From: x1 <caldridge@...>
Date: 2005-09-28T10:47:43+09:00
Subject: Re: How do I (really) encrypt a string in ruby?

 :- )

Absolutely Excellent!!

You sir, are the man!

On 9/27/05, NAKAMURA, Hiroshi <nakahiro@sarion.co.jp> wrote:
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> Hi,
>
> Michal Suchanek wrote:
> > However, encrypting 2.0M file gives 2.1M file.
>
> It may be caused by PKCS#5 padding.
>
> > Since doing encryption in C makes 2.0M ciphertext from 2.0M plaintext,
> > and it is also possible to decrypt the 2.0M ciphertext to the original
> > plaintext, something is rotten here.
> >
> > Am I missing something?
> >
> > require "openssl"
> >
> > CHLEN = 256
> > KBITS = 256
> > KLEN = 32
> > IVLEN = 16 # God knows why
>
> AES is a 128 bits (16 bytes) block cipher.
>
> > f=File.open("testkey");
> > key=f.read(KLEN)
> > f.close
> > f=File.open("testiv")
> > iv=f.read(IVLEN)
> > f.close
>
> > while (chunk=STDIN.read(CHLEN))
> >   cipher=OpenSSL::Cipher::Cipher.new("AES-256-CBC")
> >   cipher.encrypt(key,iv)
> >   cipher.key=key
> >   cipher.iv=iv
> >   STDOUT << cipher.update(chunk)
> >   STDOUT << cipher.final()
> > end
>
> This block should be:
>
> cipher=OpenSSL::Cipher::Cipher.new("AES-256-CBC")
> cipher.encrypt(key,iv)
> cipher.padding=0 # avoid PKCS#5 padding
> cipher.key=key
> cipher.iv=iv
> ciphertext = []
> while (chunk=STDIN.read(CHLEN))
>   ciphertext << cipher.update(chunk)
> end
> ciphertext << cipher.final() rescue nil # no need to call final if
> padding = 0
> print ciphertext.join
>
> Regards,
> // NaHi
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