diff --git a/year4/semester2/CT437/exam b/year4/semester2/CT437/exam
index f2252899..005c4706 100644
--- a/year4/semester2/CT437/exam
+++ b/year4/semester2/CT437/exam
@@ -1,3 +1,4 @@
 - always question about rsa and diffie helman
 - don't expecct any diffie helman calculations on the exam, that would be ridiciulous
+- "double ratchet algorithm will be covered in exam paper"
 
diff --git a/year4/semester2/CT437/materials/ct437_06 - Public Key Cryptography.pdf b/year4/semester2/CT437/materials/ct437_06 - Public Key Cryptography.pdf
index d40706a2..c9d2f012 100644
Binary files a/year4/semester2/CT437/materials/ct437_06 - Public Key Cryptography.pdf and b/year4/semester2/CT437/materials/ct437_06 - Public Key Cryptography.pdf differ