imgtool: Update docs for new key format
Update the dependencies needed, as well as adding a blurb about how to
password protect the private key.
Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/docs/imgtool.md b/docs/imgtool.md
index 27f41b8..98ba831 100644
--- a/docs/imgtool.md
+++ b/docs/imgtool.md
@@ -8,13 +8,11 @@
This program is written for Python3, and has several dependencies on
Python libraries. These can be installed using 'pip3' manually:
- pip3 install --user pycrypto
- pip3 install --user pyasn1
- pip3 install --user ecdsa
+ pip3 install --user cryptography
or, on Ubuntu, using the package manager:
- sudo apt-get install python3-crypto python3-pyasn1 python3-ecdsa
+ sudo apt-get install python3-cryptography
## Managing keys
@@ -29,6 +27,10 @@
This key file is what is used to sign images, this file should be
protected, and not widely distributed.
+You can add the `-p` argument to `keygen`, which will cause it to
+prompt for a password. You will need to enter this password in every
+time you use the private key.
+
## Incorporating the public key into the code
There is a development key distributed with mcuboot that can be used