diff --git a/cpr/auth.cpp b/cpr/auth.cpp
index b3576f5c1..841c1f5a9 100644
--- a/cpr/auth.cpp
+++ b/cpr/auth.cpp
@@ -1,7 +1,29 @@
 #include "cpr/auth.h"
 #include "cpr/util.h"
 
+#include <utility>
+
 namespace cpr {
+
+Authentication::Authentication(std::string_view username, std::string_view password, AuthMode auth_mode) : auth_mode_{auth_mode} {
+    auth_string_.reserve(username.size() + 1 + password.size());
+    auth_string_ += username;
+    auth_string_ += ':';
+    auth_string_ += password;
+}
+
+Authentication::Authentication(Authentication&& old) noexcept : auth_string_{std::move(old.auth_string_)}, auth_mode_{old.auth_mode_} {
+    old.auth_string_.resize(old.auth_string_.capacity());
+}
+
+Authentication& Authentication::operator=(Authentication&& old) noexcept {
+    auth_mode_ = old.auth_mode_;
+    util::secureStringClear(auth_string_);
+    auth_string_ = std::move(old.auth_string_);
+    old.auth_string_.resize(old.auth_string_.capacity());
+    return *this;
+}
+
 Authentication::~Authentication() noexcept {
     util::secureStringClear(auth_string_);
 }
diff --git a/include/cpr/auth.h b/include/cpr/auth.h
index e78396944..55ea0fb84 100644
--- a/include/cpr/auth.h
+++ b/include/cpr/auth.h
@@ -2,8 +2,7 @@
 #define CPR_AUTH_H
 
 #include <string>
-
-#include <utility>
+#include <string_view>
 
 namespace cpr {
 
@@ -11,12 +10,12 @@ enum class AuthMode { BASIC, DIGEST, NTLM };
 
 class Authentication {
   public:
-    Authentication(std::string username, std::string password, AuthMode auth_mode) : auth_string_{std::move(username) + ":" + std::move(password)}, auth_mode_{std::move(auth_mode)} {}
+    Authentication(std::string_view username, std::string_view password, AuthMode auth_mode);
     Authentication(const Authentication& other) = default;
-    Authentication(Authentication&& old) noexcept = default;
+    Authentication(Authentication&& old) noexcept;
     ~Authentication() noexcept;
 
-    Authentication& operator=(Authentication&& old) noexcept = default;
+    Authentication& operator=(Authentication&& old) noexcept;
     Authentication& operator=(const Authentication& other) = default;
 
     const char* GetAuthString() const noexcept;