IText PDF Won't Permit Encryption?

I am attempting to encrypt the file that is generated by Itext:

def download
  str = Rjb::import("java.lang.String");
  pw = Rjb::import("com.lowagie.text.pdf.PdfWriter")
  d = Rjb::import("com.lowagie.text.Document")
  ba = Rjb::import("java.io.ByteArrayOutputStream")
  b = ba.new()
  p = Rjb::import("com.lowagie.text.Paragraph")
  document = d.new()
  s = str.new("user")
  pwd = s.getBytes()
  writer = pw.getInstance(document, b)
  writer.setEncryption(pwd, pwd,2052,1);
  document.open()
  document.add(p.new("Hello!!!"))
  document.close()
  bytes = b.toByteArray()
  send_data(bytes, {:filename => "Letters For Printing.pdf", :type =>
"application/pdf"})
  end

Every time I call the above method I get the error :

NoClassDefFoundError in LettersController#download

org/bouncycastle/asn1/ASN1OctetString

RAILS_ROOT: C:/ruby/letter4sure
Application Trace | Framework Trace | Full Trace

app/controllers/letters_controller.rb:184:in `method_missing'
app/controllers/letters_controller.rb:184:in `download'
-e:2:in `load'
-e:2

c:/ruby/lib/ruby/gems/1.8/gems/actionpack-2.0.2/lib/action_controller/base.rb:1158:in
`send'
c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
`require'
script/server:3
-e:2:in `load'
-e:2

Request

Parameters:

{"id"=>"77"}

Show session dump