diff --git a/src/UDPC_Defines.hpp b/src/UDPC_Defines.hpp
index e43d189..16c3c29 100644
--- a/src/UDPC_Defines.hpp
+++ b/src/UDPC_Defines.hpp
@@ -39,7 +39,7 @@
 
 #define UDPC_MIN_HEADER_SIZE 20
 #define UDPC_CON_HEADER_SIZE (UDPC_MIN_HEADER_SIZE+4)
-#define UDPC_CCL_HEADER_SIZE (UDPC_MIN_HEADER_SIZE+4+crypto_sign_PUBLICKEYBYTES+8)
+#define UDPC_CCL_HEADER_SIZE (UDPC_MIN_HEADER_SIZE+4+crypto_sign_PUBLICKEYBYTES+12)
 #define UDPC_CSR_HEADER_SIZE (UDPC_MIN_HEADER_SIZE+4+crypto_sign_PUBLICKEYBYTES+crypto_sign_BYTES)
 #define UDPC_LSFULL_HEADER_SIZE (UDPC_MIN_HEADER_SIZE+1+crypto_sign_BYTES)
 #define UDPC_NSFULL_HEADER_SIZE (UDPC_MIN_HEADER_SIZE+1)
diff --git a/src/UDPConnection.cpp b/src/UDPConnection.cpp
index 01055b0..360bf84 100644
--- a/src/UDPConnection.cpp
+++ b/src/UDPConnection.cpp
@@ -671,6 +671,7 @@ void UDPC::Context::update_impl() {
                             iter->second.pk,
                             crypto_sign_PUBLICKEYBYTES);
                         // set verify message
+                        // time in seconds from epoch
                         std::time_t time = std::time(nullptr);
                         if(time <= 0) {
                             UDPC_CHECK_LOG(this, UDPC_LoggingType::UDPC_ERROR,
@@ -685,15 +686,21 @@ void UDPC::Context::update_impl() {
 # endif
                         UDPC::be64((char*)&timeInt);
                         iter->second.verifyMessage =
-                            std::unique_ptr<char[]>(new char[8]);
+                            std::unique_ptr<char[]>(new char[12]);
+                        // prepend with random data generated by client
+                        uint32_t rdata = randombytes_random();
                         std::memcpy(
                             iter->second.verifyMessage.get(),
+                            &rdata,
+                            4);
+                        std::memcpy(
+                            iter->second.verifyMessage.get() + 4,
                             &timeInt,
                             8);
                         std::memcpy(
                             buf.get() + UDPC_MIN_HEADER_SIZE + 4 + crypto_sign_PUBLICKEYBYTES,
-                            &timeInt,
-                            8);
+                            iter->second.verifyMessage.get(),
+                            12);
 #else
                         assert(!"libsodium is disabled, invalid state");
                         UDPC_CHECK_LOG(this, UDPC_LoggingType::UDPC_ERROR,
@@ -1264,7 +1271,10 @@ void UDPC::Context::update_impl() {
                 newConnection.verifyMessage = std::unique_ptr<char[]>(new char[crypto_sign_BYTES]);
                 std::time_t currentTime = std::time(nullptr);
                 uint64_t receivedTime;
-                std::memcpy(&receivedTime, recvBuf + UDPC_MIN_HEADER_SIZE + 4 + crypto_sign_PUBLICKEYBYTES, 8);
+                std::memcpy(
+                    &receivedTime,
+                    recvBuf + UDPC_MIN_HEADER_SIZE + 4 + crypto_sign_PUBLICKEYBYTES + 4,
+                    8);
                 UDPC::be64((char*)&receivedTime);
 # ifndef NDEBUG
                 if(willLog(UDPC_LoggingType::UDPC_DEBUG)) {
@@ -1283,7 +1293,7 @@ void UDPC::Context::update_impl() {
                     (unsigned char*)newConnection.verifyMessage.get(),
                     nullptr,
                     (unsigned char*)(recvBuf + UDPC_MIN_HEADER_SIZE + 4 + crypto_sign_PUBLICKEYBYTES),
-                    8,
+                    12,
                     newConnection.sk);
 #else
                 assert(!"libsodium disabled, invalid state");
@@ -1377,7 +1387,7 @@ void UDPC::Context::update_impl() {
                 if(crypto_sign_verify_detached(
                     (unsigned char*)(recvBuf + UDPC_MIN_HEADER_SIZE + 4 + crypto_sign_PUBLICKEYBYTES),
                     (unsigned char*)(iter->second.verifyMessage.get()),
-                    8,
+                    12,
                     iter->second.peer_pk) != 0) {
                     UDPC_CHECK_LOG(this, UDPC_LoggingType::UDPC_WARNING,
                         "Failed to verify peer (server) ",