Add ed25519 signing support to imgtool
This adds ed25519 signature support using the "prehash" method. Instead
of using the direct contents of the image and header payloads, a sha256
is generated and signed (SHA256-Ed25519). This allows for compatibility
with already existing tools that use the sha256 hash, like mcumgr, etc.
Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/docs/imgtool.md b/docs/imgtool.md
index dd6eed0..9d71746 100644
--- a/docs/imgtool.md
+++ b/docs/imgtool.md
@@ -12,13 +12,13 @@
## Managing keys
-This tool currently supports rsa-2048, rsa-3072 and ecdsa-p256 keys. You
-can generate a keypair for one of these types using the 'keygen' command:
+This tool currently supports rsa-2048, rsa-3072, ecdsa-p256 and ed25519 keys.
+You can generate a keypair for one of these types using the 'keygen' command:
./scripts/imgtool.py keygen -k filename.pem -t rsa-2048
-or use ecdsa-p256 for the type. The key type used should match what
-mcuboot is configured to verify.
+or use rsa-3072, ecdsa-p256, or ed25519 for the type. The key type used
+should match what mcuboot is configured to verify.
This key file is what is used to sign images, this file should be
protected, and not widely distributed.