new packages

crypto/crypto.go

@@ -0,0 +1,75 @@
+package crypto
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"encoding/hex"
+	"github.com/aead/cmac"
+)
+
+func Create_k1() (string, error) {
+
+	// 16 bytes = 128 bits
+	b := make([]byte, 16)
+	_, err := rand.Read(b)
+	if err != nil {
+		return "", err
+	}
+
+	str := hex.EncodeToString(b)
+
+	return str, nil
+}
+
+// decrypt p with aes_dec
+func Aes_decrypt(key_sdm_file_read []byte, ba_p []byte) ([]byte, error) {
+
+	dec_p := make([]byte, 16)
+	iv := make([]byte, 16)
+	c1, err := aes.NewCipher(key_sdm_file_read)
+	if err != nil {
+		return dec_p, err
+	}
+	mode := cipher.NewCBCDecrypter(c1, iv)
+	mode.CryptBlocks(dec_p, ba_p)
+
+	return dec_p, nil
+}
+
+func Aes_cmac(key_sdm_file_read_mac []byte, sv2 []byte, ba_c []byte) (bool, error) {
+
+	c2, err := aes.NewCipher(key_sdm_file_read_mac)
+	if err != nil {
+		return false, err
+	}
+	ks, err := cmac.Sum(sv2, c2, 16)
+	if err != nil {
+		return false, err
+	}
+	c3, err := aes.NewCipher(ks)
+	if err != nil {
+		return false, err
+	}
+	cm, err := cmac.Sum([]byte{}, c3, 16)
+	if err != nil {
+		return false, err
+	}
+	ct := make([]byte, 8)
+	ct[0] = cm[1]
+	ct[1] = cm[3]
+	ct[2] = cm[5]
+	ct[3] = cm[7]
+	ct[4] = cm[9]
+	ct[5] = cm[11]
+	ct[6] = cm[13]
+	ct[7] = cm[15]
+
+	res_cmac := bytes.Compare(ct, ba_c)
+	if res_cmac != 0 {
+		return false, nil
+	}
+
+	return true, nil
+}