1 files changed, 111 insertions, 0 deletions
diff --git a/docs/development/custom-vectors/arc4/verify_arc4.go b/docs/development/custom-vectors/arc4/verify_arc4.go
new file mode 100644
index 00000000..508fe980
--- /dev/null
+++ b/docs/development/custom-vectors/arc4/verify_arc4.go
@@ -0,0 +1,111 @@
+package main
+
+import (
+	"bufio"
+	"bytes"
+	"crypto/rc4"
+	"encoding/hex"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func unhexlify(s string) []byte {
+	bytes, err := hex.DecodeString(s)
+	if err != nil {
+		panic(err)
+	}
+	return bytes
+}
+
+type vectorArgs struct {
+	count      string
+	offset     uint64
+	key        string
+	plaintext  string
+	ciphertext string
+}
+
+type vectorVerifier interface {
+	validate(count string, offset uint64, key, plaintext, expectedCiphertext []byte)
+}
+
+type arc4Verifier struct{}
+
+func (o arc4Verifier) validate(count string, offset uint64, key, plaintext, expectedCiphertext []byte) {
+	if offset%16 != 0 || len(plaintext) != 16 || len(expectedCiphertext) != 16 {
+		panic(fmt.Errorf("Unexpected input value encountered: offset=%v; len(plaintext)=%v; len(expectedCiphertext)=%v",
+			offset,
+			len(plaintext),
+			len(expectedCiphertext)))
+	}
+	stream, err := rc4.NewCipher(key)
+	if err != nil {
+		panic(err)
+	}
+
+	var currentOffset uint64 = 0
+	ciphertext := make([]byte, len(plaintext))
+	for currentOffset <= offset {
+		stream.XORKeyStream(ciphertext, plaintext)
+		currentOffset += uint64(len(plaintext))
+	}
+	if !bytes.Equal(ciphertext, expectedCiphertext) {
+		panic(fmt.Errorf("vector mismatch @ COUNT = %s:\n  %s != %s\n",
+			count,
+			hex.EncodeToString(expectedCiphertext),
+			hex.EncodeToString(ciphertext)))
+	}
+}
+
+func validateVectors(verifier vectorVerifier, filename string) {
+	vectors, err := os.Open(filename)
+	if err != nil {
+		panic(err)
+	}
+	defer vectors.Close()
+
+	var segments []string
+	var vector *vectorArgs
+
+	scanner := bufio.NewScanner(vectors)
+	for scanner.Scan() {
+		segments = strings.Split(scanner.Text(), " = ")
+
+		switch {
+		case strings.ToUpper(segments[0]) == "COUNT":
+			if vector != nil {
+				verifier.validate(vector.count,
+					vector.offset,
+					unhexlify(vector.key),
+					unhexlify(vector.plaintext),
+					unhexlify(vector.ciphertext))
+			}
+			vector = &vectorArgs{count: segments[1]}
+		case strings.ToUpper(segments[0]) == "OFFSET":
+			vector.offset, err = strconv.ParseUint(segments[1], 10, 64)
+			if err != nil {
+				panic(err)
+			}
+		case strings.ToUpper(segments[0]) == "KEY":
+			vector.key = segments[1]
+		case strings.ToUpper(segments[0]) == "PLAINTEXT":
+			vector.plaintext = segments[1]
+		case strings.ToUpper(segments[0]) == "CIPHERTEXT":
+			vector.ciphertext = segments[1]
+		}
+	}
+	if vector != nil {
+		verifier.validate(vector.count,
+			vector.offset,
+			unhexlify(vector.key),
+			unhexlify(vector.plaintext),
+			unhexlify(vector.ciphertext))
+	}
+}
+
+func main() {
+	validateVectors(arc4Verifier{}, "vectors/cryptography_vectors/ciphers/ARC4/arc4.txt")
+	fmt.Println("ARC4 OK.")
+}