Move previous cryptopals work into an Erlang subfolder, start cryptopals in Python 3

[sandbox] / cryptopals-erlang / 01.02 / hex.erl

diff --git a/cryptopals-erlang/01.02/hex.erl b/cryptopals-erlang/01.02/hex.erl
new file mode 100644 (file)
index 0000000..9c39538
--- /dev/null
+++ b/cryptopals-erlang/01.02/hex.erl
@@ -0,0 +1,23 @@
+-module(hex).
+-export([decode/1,encode/1,fixed_xor/2]).
+
+data_in_pairs([]) -> [];
+data_in_pairs([C1,C2|Tail]) -> [ [C1] ++ [C2] | data_in_pairs(Tail) ].
+
+decode(Data) -> [ list_to_integer(P,16) || P <- data_in_pairs(Data) ]. 
+
+fixed_xor(Data1,Data2) ->
+    DecodedData1 = decode(Data1),
+    DecodedData2 = decode(Data2),
+    XoredData = lists:zipwith(
+        fun(P1,P2) -> P1 bxor P2 end,
+        DecodedData1,
+        DecodedData2),
+    encode(XoredData).
+
+encode(L) -> string:join(lists:map(fun(X) -> int_to_hex(X) end, L), "").
+ 
+int_to_hex(N) when N < 256 -> [hex(N div 16), hex(N rem 16)].
+ 
+hex(N) when (0  =< N) and (N < 10) -> $0 + N;
+hex(N) when (10 =< N) and (N < 16) -> $a + (N-10).