(ql:quickload :cl-base64)
(ql:quickload :iterate)
(ql:quickload :fiveam)

(use-package :iterate)
(use-package :fiveam)

(def-suite cryptopals)
(in-suite cryptopals)

(defun hex-to-dec (hex-chr)
  (cond
    ((char<= #\0 hex-chr #\9)
     (- (char-code hex-chr) (char-code #\0)))
    ((char<= #\a hex-chr #\f)
     (+ (- (char-code hex-chr) (char-code #\a)) 10))
    ((char<= #\A hex-chr #\F)
     (+ (- (char-code hex-chr) (char-code #\A)) 10))))

(defun dec-to-hex (dec-chr)
  (cond
    ((<= 0 dec-chr 9) (code-char (+ (char-code #\0) dec-chr)))
    ((<= 10 dec-chr 15) (code-char (+ (char-code #\a) (- dec-chr 10))))))

(defun hex-to-bytes (hex-str)
  (iter
    (for i below (length hex-str) by 2)
    (let ((c1 (hex-to-dec (aref hex-str i)))
          (c2 (hex-to-dec (aref hex-str (1+ i)))))
        (collect (+ (* 16 c1) c2) result-type (vector (unsigned-byte 8)))))) 

(defun bytes-to-hex (bytes)
  (iter
    (for i in-vector bytes)
    (collect (dec-to-hex (ash (logand i #xff) -4)) result-type string)
    (collect (dec-to-hex (logand i #xf)) result-type string)))

;; set 1 challenge 1
(defun hex-to-base64 (hex-str)
  (cl-base64:usb8-array-to-base64-string (hex-to-bytes hex-str)))

(test s1c1
  (let ((in "49276d206b696c6c696e6720796f757220627261696e206c696b65206120706f69736f6e6f7573206d757368726f6f6d")
        (out "SSdtIGtpbGxpbmcgeW91ciBicmFpbiBsaWtlIGEgcG9pc29ub3VzIG11c2hyb29t"))
    (is (string= (hex-to-base64 in) out))))

;; set 1 challenge 2
(defun fixed-xor (s1 s2)
  (bytes-to-hex 
    (iter
      (for x in-vector (hex-to-bytes s1))
      (for y in-vector (hex-to-bytes s2))
      (collect (logxor x y) result-type (vector (unsigned-byte 8))))))

(test s1c2
  (let ((in1 "1c0111001f010100061a024b53535009181c")
        (in2 "686974207468652062756c6c277320657965")
        (out "746865206b696420646f6e277420706c6179"))
    (is (string= (fixed-xor in1 in2) out))))

(run! 'cryptopals)