diff --git a/docs_src/nfc_technical_details.md b/docs_src/nfc_technical_details.md
index 5ed9dbd..d7f5802 100644
--- a/docs_src/nfc_technical_details.md
+++ b/docs_src/nfc_technical_details.md
@@ -18,6 +18,10 @@
    - New keys can easily be introduced without breaking backwards compatibility.
    - Deprecated keys will never be reused.
    - If there would be substantial changes to the standard that would break backwards compatibility, a new MIME type will be used for the new format.
+1. The standard does not attempt to provide anti-counterfeiting or tag authenticity.
+   - A NFC tag can be cloned verbatim, or the contents of the container it is attached to can be changed, and no on-tag mechanism can prevent this.
+   - For these reasons the standard **does not define on-tag cryptographic signing**, which would cost scarce tag memory while providing marginal benefit.
+   - Additional authenticity measures (for example looking up the tag UID against a database) can be employed by the manufacturers, but are out of scope of this specification.
 
 ## 3. Tag operations
 The OpenPrintTag standard defines these types of operations with the tag:
diff --git a/docs_src/sample_data/sample_key.pem b/docs_src/sample_data/sample_key.pem
deleted file mode 100644
index 42eece4..0000000
--- a/docs_src/sample_data/sample_key.pem
+++ /dev/null
@@ -1,8 +0,0 @@
------BEGIN EC PARAMETERS-----
-BgUrgQQACg==
------END EC PARAMETERS-----
------BEGIN EC PRIVATE KEY-----
-MHQCAQEEICd7bXiTa8ktvMpx67MzJsJ7hy7UNGWi6tsZuY4E7/cZoAcGBSuBBAAK
-oUQDQgAEOlJ7w+cjw6+SMmimw/nm/VMDFN84Y9X7E9viE5L5TIi1Lhw6/nvcTBQY
-wfhve5oEiunX2MjxCvOpnlYroShb5w==
------END EC PRIVATE KEY-----
diff --git a/docs_src/sample_data/sample_key.pub b/docs_src/sample_data/sample_key.pub
deleted file mode 100644
index 6732d63..0000000
--- a/docs_src/sample_data/sample_key.pub
+++ /dev/null
@@ -1,4 +0,0 @@
------BEGIN PUBLIC KEY-----
-MFYwEAYHKoZIzj0CAQYFK4EEAAoDQgAEOlJ7w+cjw6+SMmimw/nm/VMDFN84Y9X7
-E9viE5L5TIi1Lhw6/nvcTBQYwfhve5oEiunX2MjxCvOpnlYroShb5w==
------END PUBLIC KEY-----