diff --git a/src/main/scala/uk/ac/soton/ecs/can/core/ChaChaBlock.scala b/src/main/scala/uk/ac/soton/ecs/can/core/ChaChaBlock.scala
index 4ee15ff90ec76b42d3fd76bb0afd6680153dc4fc..58350e9504257c5c56621ec5ac6635b3c6d01a72 100644
--- a/src/main/scala/uk/ac/soton/ecs/can/core/ChaChaBlock.scala
+++ b/src/main/scala/uk/ac/soton/ecs/can/core/ChaChaBlock.scala
@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2021 Minyong Li <ml10g20@soton.ac.uk>
+// SPDX-License-Identifier: CERN-OHL-W-2.0
+
 package uk.ac.soton.ecs.can.core
 
 import chisel3._
diff --git a/src/main/scala/uk/ac/soton/ecs/can/core/ChaChaInnerBlock.scala b/src/main/scala/uk/ac/soton/ecs/can/core/ChaChaInnerBlock.scala
index ad5ef01f78c972c6043d41c39d7e206b3e395317..9068d0c01df71f6b0c56738ff38b65f9bcb19b27 100644
--- a/src/main/scala/uk/ac/soton/ecs/can/core/ChaChaInnerBlock.scala
+++ b/src/main/scala/uk/ac/soton/ecs/can/core/ChaChaInnerBlock.scala
@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2021 Minyong Li <ml10g20@soton.ac.uk>
+// SPDX-License-Identifier: CERN-OHL-W-2.0
+
 package uk.ac.soton.ecs.can.core
 
 import chisel3._
diff --git a/src/main/scala/uk/ac/soton/ecs/can/core/ColumnRound.scala b/src/main/scala/uk/ac/soton/ecs/can/core/ColumnRound.scala
index 367d1253c3aa351788e1d16c86c61c81a5e615e3..edabce222447ad197ba510ed6788ecb61975d004 100644
--- a/src/main/scala/uk/ac/soton/ecs/can/core/ColumnRound.scala
+++ b/src/main/scala/uk/ac/soton/ecs/can/core/ColumnRound.scala
@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2021 Minyong Li <ml10g20@soton.ac.uk>
+// SPDX-License-Identifier: CERN-OHL-W-2.0
+
 package uk.ac.soton.ecs.can.core
 
 import chisel3._
diff --git a/src/main/scala/uk/ac/soton/ecs/can/core/DiagonalRound.scala b/src/main/scala/uk/ac/soton/ecs/can/core/DiagonalRound.scala
index 8e93499420e2c6902db00b58abc38a00dc548552..4d7b04e4de8b4ef93b7c94185011eed110af1dd9 100644
--- a/src/main/scala/uk/ac/soton/ecs/can/core/DiagonalRound.scala
+++ b/src/main/scala/uk/ac/soton/ecs/can/core/DiagonalRound.scala
@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2021 Minyong Li <ml10g20@soton.ac.uk>
+// SPDX-License-Identifier: CERN-OHL-W-2.0
+
 package uk.ac.soton.ecs.can.core
 
 import chisel3._
diff --git a/src/test/scala/uk/ac/soton/ecs/can/core/ChaChaBlockTest.scala b/src/test/scala/uk/ac/soton/ecs/can/core/ChaChaBlockTest.scala
index 5b0ffd9cea0f2511e0f6214fbf2da5fd640fe617..62f101f59f7548b9d611b51cff3298e53bdfe4ee 100644
--- a/src/test/scala/uk/ac/soton/ecs/can/core/ChaChaBlockTest.scala
+++ b/src/test/scala/uk/ac/soton/ecs/can/core/ChaChaBlockTest.scala
@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2021 Minyong Li <ml10g20@soton.ac.uk>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package uk.ac.soton.ecs.can.core
 
 import org.scalatest._