diff --git a/samples/zephyr/bad-keys/README.md b/samples/zephyr/bad-keys/README.md
new file mode 100644
index 0000000..621ce96
--- /dev/null
+++ b/samples/zephyr/bad-keys/README.md
@@ -0,0 +1,6 @@
+# Bad keys for testing
+
+This directory contains some alternate keys that can be used for
+testing.  Signing the images with either of these keys, but leaving
+the demo keys's public keys in the bootloader should result in it not
+upgrading, or not booting.
diff --git a/samples/zephyr/bad-keys/bad-ec-p256.pem b/samples/zephyr/bad-keys/bad-ec-p256.pem
new file mode 100644
index 0000000..333f41f
--- /dev/null
+++ b/samples/zephyr/bad-keys/bad-ec-p256.pem
@@ -0,0 +1,5 @@
+-----BEGIN EC PRIVATE KEY-----
+MHcCAQEEILmqmiH6y3EGhLkTcnNtU7hZ1wnc51MIL53npseRX7vJoAoGCCqGSM49
+AwEHoUQDQgAEcX9ExNjZfsckp6AdutjPjVJsvP6ZZkKfLsGnRpKR+9OpO9/qmJHs
+ks+ZXo70SEANjWnNlxKNAVci8aUm8UskLw==
+-----END EC PRIVATE KEY-----
diff --git a/samples/zephyr/bad-keys/bad-rsa-2048.pem b/samples/zephyr/bad-keys/bad-rsa-2048.pem
new file mode 100644
index 0000000..755f95b
--- /dev/null
+++ b/samples/zephyr/bad-keys/bad-rsa-2048.pem
@@ -0,0 +1,27 @@
+-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----
\ No newline at end of file