doc: signature.txt: Document devicetree format for ECDSA keys
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/doc/uImage.FIT/signature.txt b/doc/uImage.FIT/signature.txt
index a345588..0139295 100644
--- a/doc/uImage.FIT/signature.txt
+++ b/doc/uImage.FIT/signature.txt
@@ -142,7 +142,7 @@
Public keys should be stored as sub-nodes in a /signature node. Required
properties are:
-- algo: Algorithm name (e.g. "sha1,rsa2048")
+- algo: Algorithm name (e.g. "sha1,rsa2048" or "sha256,ecdsa256")
Optional properties are:
@@ -167,6 +167,11 @@
- rsa,r-squared: (2^num-bits)^2 as a big-endian multi-word integer
- rsa,n0-inverse: -1 / modulus[0] mod 2^32
+For ECDSA the following are mandatory:
+- ecdsa,curve: Name of ECDSA curve (e.g. "prime256v1")
+- ecdsa,x-point: Public key X coordinate as a big-endian multi-word integer
+- ecdsa,y-point: Public key Y coordinate as a big-endian multi-word integer
+
These parameters can be added to a binary device tree using parameter -K of the
mkimage command::