add code to Hash and Verify the PIN

common/pin.go

@@ -1,6 +1,10 @@
 package common
 
-import "regexp"
+import (
+	"regexp"
+
+	"golang.org/x/crypto/bcrypt"
+)
 
 // Define the regex pattern as a constant
 const (
@@ -12,3 +16,18 @@ func IsValidPIN(pin string) bool {
 	match, _ := regexp.MatchString(pinPattern, pin)
 	return match
 }
+
+// HashPIN uses bcrypt with 8 salt rounds to hash the PIN
+func HashPIN(pin string) (string, error) {
+	hash, err := bcrypt.GenerateFromPassword([]byte(pin), 8)
+	if err != nil {
+		return "", err
+	}
+	return string(hash), nil
+}
+
+// VerifyPIN compareS the hashed PIN with the plaintext PIN
+func VerifyPIN(hashedPIN, pin string) bool {
+	err := bcrypt.CompareHashAndPassword([]byte(hashedPIN), []byte(pin))
+	return err == nil
+}