diff --git a/.DS_Store b/.DS_Store
index 1546f92..32fce50 100644
Binary files a/.DS_Store and b/.DS_Store differ
diff --git a/dhparams.pem b/dhparams.pem
new file mode 100644
index 0000000..8532b61
--- /dev/null
+++ b/dhparams.pem
@@ -0,0 +1,15 @@
+    DH Parameters: (738 bit)
+    P:   
+        02:53:0a:a9:d3:a8:05:b6:40:0b:8c:30:ed:d9:37:
+        26:f7:a4:ac:9f:4f:e2:8b:25:6f:af:34:a5:fa:48:
+        d1:50:b0:ad:16:19:e4:06:dd:5d:12:fa:6a:70:87:
+        55:02:c9:bb:58:1c:9f:3f:15:75:d3:35:24:49:a8:
+        20:85:05:1c:69:c5:61:d7:49:45:28:91:65:65:58:
+        1b:86:1f:6a:be:15:81:67:bf:f0:43:68:a5:61:2b:
+        13:87:db
+    G:    5 (0x5)
+-----BEGIN DH PARAMETERS-----
+MGICXQJTCqnTqAW2QAuMMO3ZNyb3pKyfT+KLJW+vNKX6SNFQsK0WGeQG3V0S+mpw
+h1UCybtYHJ8/FXXTNSRJqCCFBRxpxWHXSUUokWVlWBuGH2q+FYFnv/BDaKVhKxOH
+2wIBBQ==
+-----END DH PARAMETERS-----
diff --git a/unit04_public_key/lab/gpg/hello1.txt b/unit04_public_key/lab/gpg/hello1.txt
new file mode 100644
index 0000000..b13970a
--- /dev/null
+++ b/unit04_public_key/lab/gpg/hello1.txt
@@ -0,0 +1 @@
+It is getting so difficult to tell online what is real and what is not; we really have to move towards public key signing of messages and content.
diff --git a/unit04_public_key/lab/gpg/hello1.txt.asc b/unit04_public_key/lab/gpg/hello1.txt.asc
new file mode 100644
index 0000000..2aa2102
--- /dev/null
+++ b/unit04_public_key/lab/gpg/hello1.txt.asc
@@ -0,0 +1,20 @@
+-----BEGIN PGP MESSAGE-----
+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+=qMBi
+-----END PGP MESSAGE-----
diff --git a/unit05_key_exchange/lecture/unit05_key_exchange.pptx b/unit05_key_exchange/lecture/unit05_key_exchange.pptx
index e483ab4..76344e3 100644
Binary files a/unit05_key_exchange/lecture/unit05_key_exchange.pptx and b/unit05_key_exchange/lecture/unit05_key_exchange.pptx differ
diff --git a/z_assessments/.DS_Store b/z_assessments/.DS_Store
index 56d3685..7d446b8 100644
Binary files a/z_assessments/.DS_Store and b/z_assessments/.DS_Store differ
diff --git a/z_assessments/test01/.DS_Store b/z_assessments/test01/.DS_Store
index bebc553..a202c70 100644
Binary files a/z_assessments/test01/.DS_Store and b/z_assessments/test01/.DS_Store differ
diff --git a/z_assessments/test01/slides/applied_crypto_revision01.pptx b/z_assessments/test01/slides/applied_crypto_revision01.pptx
index 9577526..44e6d2e 100644
Binary files a/z_assessments/test01/slides/applied_crypto_revision01.pptx and b/z_assessments/test01/slides/applied_crypto_revision01.pptx differ