From: Brian Candler <b.candler@...>
Date: 2008-10-18T01:04:59+09:00
Subject: Re: RSA public_encrypt bug?

Dani Pardo wrote:
>  Actually, what I've found out is that after populating the modulus
> and exponent, if I print the key:
> 
>  --
> rsa.n = OpenSSL::BN.new  f.gets
> rsa.e = OpenSSL::BN.new f.gets
> 
> puts rsa.to_text
> ---
> 
>  The modulus that #to_text reports doesn't ressemble what I have on
> the public key I've got on a text file.. :?

You want to post your n and e here? They are a *public* key, after all 
:-)

>  Also, the modulus reported by #to_text is 51 bytes (?), while the
> public modulus I've got in the text file is 128 characters in hex,
> which is 64 bytes.

Aha! OpenSSL::BN reads decimal, not hex! Remember that irb is your 
friend:

irb(main):001:0> require 'openssl'
=> true
irb(main):002:0> x = OpenSSL::BN.new("1234")
=> 1234
irb(main):003:0> x = OpenSSL::BN.new("12AB")
=> 12

So try changing your code to:

  rsa.n = OpenSSL::BN.new(f.gets.to_i(16).to_s)

Or more simply, you should just be able to write:

  rsa.n = f.gets.to_i(16)
-- 
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