diff --git a/dh.pem b/dh.pem
new file mode 100644
index 0000000..c453fde
--- /dev/null
+++ b/dh.pem
@@ -0,0 +1,29 @@
+    DH Parameters: (2048 bit)
+    P:   
+        00:f8:21:85:5e:de:b1:ef:7e:e5:d1:77:c3:13:cc:
+        6f:36:82:61:19:36:50:11:c7:16:19:a8:b3:52:2c:
+        47:9c:4d:ee:42:4d:ac:16:61:90:2e:1e:cf:23:22:
+        af:75:53:e8:03:27:5b:b4:0f:0e:bc:97:04:a2:b4:
+        f4:6f:00:07:c7:eb:c4:f4:11:a1:c1:88:4b:99:ab:
+        48:f4:23:e5:d9:ed:60:48:a6:f5:91:c4:4b:03:90:
+        75:21:9b:99:66:84:30:76:a9:ad:6c:dc:47:08:05:
+        b8:ce:b4:2b:e1:56:a0:63:ad:ab:74:87:a3:b8:fa:
+        12:5f:a5:f6:d4:e4:b6:ab:fe:95:7f:1f:fd:05:66:
+        87:d4:a2:8f:97:fb:4b:d6:f2:3d:ea:b7:0a:59:1f:
+        cb:77:66:9c:80:8e:20:b5:b1:a2:71:c9:63:f0:d7:
+        8e:ec:9f:57:23:1f:e4:73:c8:27:b0:a1:5b:81:b9:
+        aa:22:af:c9:b0:3c:95:b4:14:fb:7b:91:88:1d:de:
+        2e:1f:18:18:5d:4a:35:cb:4d:80:ae:c4:4b:9c:ac:
+        e5:e7:02:ac:dc:9e:10:bc:2f:e7:91:d7:7b:51:b3:
+        01:30:e4:5c:20:5d:ac:18:7a:a9:ca:16:f6:eb:4f:
+        85:6b:d9:66:c3:cd:39:2f:5b:7c:ed:d0:f0:8e:a3:
+        4b:cf
+    G:    2 (0x2)
+-----BEGIN DH PARAMETERS-----
+MIIBCAKCAQEA+CGFXt6x737l0XfDE8xvNoJhGTZQEccWGaizUixHnE3uQk2sFmGQ
+Lh7PIyKvdVPoAydbtA8OvJcEorT0bwAHx+vE9BGhwYhLmatI9CPl2e1gSKb1kcRL
+A5B1IZuZZoQwdqmtbNxHCAW4zrQr4VagY62rdIejuPoSX6X21OS2q/6Vfx/9BWaH
+1KKPl/tL1vI96rcKWR/Ld2acgI4gtbGicclj8NeO7J9XIx/kc8gnsKFbgbmqIq/J
+sDyVtBT7e5GIHd4uHxgYXUo1y02ArsRLnKzl5wKs3J4QvC/nkdd7UbMBMORcIF2s
+GHqpyhb260+Fa9lmw805L1t87dDwjqNLzwIBAg==
+-----END DH PARAMETERS-----
diff --git a/dhparams.pem b/dhparams.pem
new file mode 100644
index 0000000..b95be33
--- /dev/null
+++ b/dhparams.pem
@@ -0,0 +1,15 @@
+    DH Parameters: (768 bit)
+    P:   
+        00:f4:4d:66:fc:65:d8:fd:43:3f:38:b2:9b:98:85:
+        4d:d4:7b:09:32:13:0c:50:d1:78:d2:6e:65:a2:bf:
+        2c:75:23:94:46:ea:95:9c:c7:6d:d5:8c:87:53:03:
+        b4:5e:f6:9e:86:91:26:b2:a8:d7:69:40:c4:cd:54:
+        5f:39:64:42:e8:bb:3f:84:20:76:57:54:c6:0b:b6:
+        77:16:0e:52:9f:fc:d8:ad:3d:da:71:2f:d3:c5:2b:
+        70:aa:55:f5:2d:4f:cf
+    G:    2 (0x2)
+-----BEGIN DH PARAMETERS-----
+MGYCYQD0TWb8Zdj9Qz84spuYhU3UewkyEwxQ0XjSbmWivyx1I5RG6pWcx23VjIdT
+A7Re9p6GkSayqNdpQMTNVF85ZELouz+EIHZXVMYLtncWDlKf/NitPdpxL9PFK3Cq
+VfUtT88CAQI=
+-----END DH PARAMETERS-----
diff --git a/secp256k1.pem b/secp256k1.pem
new file mode 100644
index 0000000..32d952e
--- /dev/null
+++ b/secp256k1.pem
@@ -0,0 +1,3 @@
+-----BEGIN EC PARAMETERS-----
+BgUrgQQACg==
+-----END EC PARAMETERS-----
diff --git a/unit04_public_key/lab/gpg/hello.txt.asc b/unit04_public_key/lab/gpg/hello.txt.asc
index 0014fa5..47dfd7c 100644
--- a/unit04_public_key/lab/gpg/hello.txt.asc
+++ b/unit04_public_key/lab/gpg/hello.txt.asc
@@ -1,15 +1,10 @@
 -----BEGIN PGP MESSAGE-----
 
-hQGMA3Cdd8yfcY0gAQv/Xb5KUhugnVJMB67lzy4B15BZw3eCb3zUM8vXSUZ/0hKq
-xiAIgfNNTwbiThiwHGM74moTBfDCMhi4lVa1ooxhNgHr5e6UtxeoQ9sew7vnrrM+
-sHRwhl+KRL+wD6oiQU+OE/nPk8yY3FkDCY0JfMkfzB6AbNZcgknSuiGEAbxtxVOq
-3KJensnToO2eaNDZKXeheIT68XP+ik3O5SAsKUAhDK2GRvEfvRyA18IWWCVKNwzH
-iyyJJheXfESgmwvcxFF0aQmZGyU+6g8gzR1IJyKA8JtzCuFLJyJXn3zPxbCw9YrU
-1DUwLeOH2/OJTJ1VM+ZQSinhySp3i5bk/eQwQsua+oe6emzhlmZRFfIhCIcgiBh3
-+7DL7ZWd+goi4/4OEa47I2WMuDG8ypm0pyaD8qaZl6337c94daNYpBnbUAbK90Ya
-JOwD03hOW18yPqSImtXSQ9h037OC7Szhg4LwrMRusn8kR+KDnryVWHjvIez7kWQa
-lwkAeND1q4jEhHBHUWvD0mkBFo1NmuXHafx83ZnWA5QDzqzQSN0vCsjkoNhvQIq9
-orEBkcYKfAC4Q0U9RM2IvAsEnWpW2nSq3I0+zYYlrLCIkintEBZ9WZDyRzeSB0kj
-eXTXwO2A0ypvfjXh7b3phYl0HxKrjEeN9X8=
-=wCBU
+hIwDr3F+ZV20YI8BBACBbtF1HV4FX29DfsIVfoY6UIjDxHvSZ49GgmiuZg4Z1S7K
+g8+I9iBsJKBFfThZ0HD/xVsMd4Q/VH4vq/P1kLnP60DNq4m8Ka3N72e01bZZ/u2t
+bN2cay2W+iArfB/a3ng7Ic+4hhiPfnqRgBFPMBgszsIBaAgX23JfK9tkAWZlaNJp
+AXw5I3DXu5FWVuxeZyp65uJEj01jQcowt3Q7NGTHLmsSkv2b3M2Qvh8UEmbvvJTj
+uWeNdv2oY79W7SSFMSTD5IpoUeMD1FRjlx6f8MQm0nK9nKO8oUGEUfD6ErTmO9Es
+b6huSmHsMfBW
+=8Bs8
 -----END PGP MESSAGE-----
diff --git a/unit05_key_exchange/.DS_Store b/unit05_key_exchange/.DS_Store
index 6721e67..7e84495 100644
Binary files a/unit05_key_exchange/.DS_Store and b/unit05_key_exchange/.DS_Store differ
diff --git a/unit05_key_exchange/lecture/unit05_key_exchange.pptx b/unit05_key_exchange/lecture/unit05_key_exchange.pptx
index 7b8beec..a539413 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_ctf/README.md b/z_ctf/README.md
new file mode 100644
index 0000000..8d379df
--- /dev/null
+++ b/z_ctf/README.md
@@ -0,0 +1,12 @@
+-----BEGIN ENCRYPTED PRIVATE KEY-----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+-----END ENCRYPTED PRIVATE KEY-----