;; mzcrypto: libcrypto bindings for PLT-scheme
;; BN interface
;;
;; (C) Copyright 2007-2009 Dimitris Vyzovitis <vyzo at media.mit.edu>
;;
;; mzcrypto is free software: you can redistribute it and/or modify
;; it under the terms of the GNU Lesser General Public License as published
;; by the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;;
;; mzcrypto is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU Lesser General Public License for more details.
;;
;; You should have received a copy of the GNU Lesser General Public License
;; along with mzcrypto.  If not, see <http://www.gnu.org/licenses/>.
#lang scheme/base

(require scheme/foreign
         "libcrypto.ss"
         "macros.ss"
         "error.ss"
         "util.ss")

(provide (all-defined-out))

(define/alloc BN)
(define/ffi (BN_add_word _pointer _ulong) -> _int : check-error)
(define/ffi (BN_dup _pointer) -> _pointer : pointer/error)
(define/ffi (BN_num_bits _pointer) -> _int)
(define/ffi (BN_bn2bin _pointer _bytes) -> _int)
(define/ffi (BN_bin2bn (bs : _bytes) (_int = (bytes-length bs)) 
                       (_pointer = #f) ) 
  -> _pointer : pointer/error)

(define (bn-size bn)
  (ceiling (/ (BN_num_bits bn) 8)))

(define (bn->bytes bn)
  (let ((bs (make-bytes (bn-size bn))))
    (shrink-bytes bs (BN_bn2bin bn bs))))
  
(define (bytes->bn bs)
  (BN_bin2bn bs))