lib: update RepeatingXOR

- Change input type to []byte.
- Change retur type to []byte.
- Update RepeatingXOR calls in challenge 5 an 6.

3 files changed, 15 insertions, 21 deletions

diff --git a/challenge/c05.go b/challenge/c05.go
index a9b1682..a1413ef 100644
--- a/challenge/c05.go
+++ b/challenge/c05.go
@@ -10,12 +10,12 @@ import (
 )
 
 func C5() {
-	icebaby := `Burning 'em, if you ain't quick and nimble
-I go crazy when I hear a cymbal`
-	key := "ICE"
-	es := lib.RepeatingXOR(icebaby, key)
-	hs := lib.AsciiStrToHexStr(es)
-	fmt.Printf("RepeatingXOR('%v', '%v') = %v\n", icebaby, key, hs)
+	icebaby := lib.StrToBytes(`Burning 'em, if you ain't quick and nimble
+I go crazy when I hear a cymbal`)
+	key := lib.StrToBytes("ICE")
+	eb := lib.RepeatingXOR(icebaby, key)
+	hs := lib.AsciiStrToHexStr(lib.BytesToStr(eb))
+	fmt.Printf("RepeatingXOR('%s', '%s') = %v\n", icebaby, key, hs)
 }
 
 // Output:
diff --git a/challenge/c06.go b/challenge/c06.go
index 589236b..5d19146 100644
--- a/challenge/c06.go
+++ b/challenge/c06.go
@@ -94,17 +94,17 @@ Jk8DCkkcC3hFMQIEC0EbAVIqCFZBO1IdBgZUVA4QTgUWSR4QJwwRTWM=`
 	}
 	// 'bs' is the data to decrypt.
 	// 'ks' is the key size.
-	crack := func(bs []byte, ks int) (string, string) {
+	crack := func(bs []byte, ks int) ([]byte, []byte) {
 		blocks := lib.BreakIntoBlocks(bs, ks)
 		blocks = lib.TransposeBlocks(blocks, ks)
 
-		key := ""
+		key := make([]byte, 0)
 		for i := 0; i < len(blocks); i++ {
 			k := findKey(blocks[i])
 
-			key += string(k)
+			key = append(key, k)
 		}
-		return key, lib.RepeatingXOR(string(bs), key)
+		return key, lib.RepeatingXOR(bs, key)
 	}
 
 	// Compute keysize.
diff --git a/lib/xor.go b/lib/xor.go
index 7b57d82..31a4b8b 100644
--- a/lib/xor.go
+++ b/lib/xor.go
@@ -35,29 +35,23 @@ func FixedXORBytes(as, bs []byte) []byte {
 }
 
 // Both 'data' and 'key' need to be plain ascii string.
-func RepeatingXOR(data, key string) string {
-	xs := ""
+func RepeatingXOR(data, key []byte) []byte {
+	xs := make([]byte, 0)
 	if len(data) < 1 || len(key) < 1 {
 		return xs
 	}
 
-	// data in bytes
-	db := []byte(data)
-
-	// key in bytes
-	dk := []byte(key)
-
 	lk := len(key)
-	for i, ki := 0, 0; i < len(db); i++ {
+	for i, ki := 0, 0; i < len(data); i++ {
 		if ki == lk {
 			ki = 0
 		}
 
 		// xor a byte
-		eb := db[i] ^ dk[ki]
+		eb := data[i] ^ key[ki]
 
 		// append to result
-		xs += string(eb)
+		xs = append(xs, eb)
 
 		ki += 1
 	}