diff --git a/src/protocol/CryptionHandler.cpp b/src/protocol/CryptionHandler.cpp
index 18c6e1c..1cd73f6 100644
--- a/src/protocol/CryptionHandler.cpp
+++ b/src/protocol/CryptionHandler.cpp
@@ -108,7 +108,7 @@ void _fe_neg(fe h, const fe f) {
 	h[9] = h9;
 }
 
-inline std::string keyMul(const uint8_t* publicKey /* compressed */, const uint8_t* privateKey /* uncompressed */, bool negate){
+inline void keyMul(uint8_t* target_buffer, const uint8_t* publicKey /* compressed */, const uint8_t* privateKey /* uncompressed */, bool negate){
 	ge_p3 keyA{};
 	ge_p2 result{};
 
@@ -119,9 +119,7 @@ inline std::string keyMul(const uint8_t* publicKey /* compressed */, const uint8
 	}
 	ge_scalarmult_vartime(&result, privateKey, &keyA);
 
-	char buffer[32];
-	ge_tobytes((uint8_t*) buffer, &result);
-	return string(buffer, 32);
+	ge_tobytes(target_buffer, &result);
 }
 
 bool CryptionHandler::setupSharedSecretNew(const std::string &alpha, const std::string &beta, const char* privateKey /* uncompressed */, const char* publicKey /* compressed */) {
@@ -132,7 +130,7 @@ bool CryptionHandler::setupSharedSecretNew(const std::string &alpha, const std::
 	string sharedIv;
 	shared.resize(32, '\0');
 	sharedIv.resize(64, '\0');
-	shared = keyMul(reinterpret_cast<const uint8_t *>(publicKey), reinterpret_cast<const uint8_t *>(privateKey), true); //Remote key get negated
+	keyMul((uint8_t*) shared.data(), reinterpret_cast<const uint8_t *>(publicKey), reinterpret_cast<const uint8_t *>(privateKey), true); //Remote key get negated
 	sharedIv = digest::sha512(shared);
 
 	auto xor_key = alpha + beta;