zephyr: Support RSA, and ECDSA P-256 signing
Make it clear in the top-level Makefile how to configure mcuboot for
Zephyr for a particular signing algorithm. Currently supported, are the
RSA signatures, and ECDSA with the P-256 curve. These configuration
lines will select the code built in the bootloader, as well as which
public key gets included with the image.
This also adds a demo public key for the P-256 signatures.
diff --git a/root-ec-p256.pem b/root-ec-p256.pem
new file mode 100644
index 0000000..2f4accf
--- /dev/null
+++ b/root-ec-p256.pem
@@ -0,0 +1,5 @@
+-----BEGIN EC PRIVATE KEY-----
+MHcCAQEEINeY1S+DASQ701QrflXtTHRhGQCw+VBagk/h6OwGO8/xoAoGCCqGSM49
+AwEHoUQDQgAEKstAPOj+7VukSZWhqR2u6Nu+GTfNFPsvJFc35ZU5iNmUudZa69fN
+1TCK1v5IskpqgQ7l8H2LaDTMOmr8U476wQ==
+-----END EC PRIVATE KEY-----