Remove the key_id field from the image header. There are two problems
with this field. First, it is only an integer offset, and so causes an
unnecessarily tight coupling between the particular keys built into the
bootloader, and the key that is used to sign. Second, it makes the
key_id part of the image header, which is included in the signature.
This makes it impossible to later sign the image with a different
signature.
Instead of the key-id, add a TLV KEYHASH entry. This will hold the
SHA256 of the public key that the signature is against. Each signature
placed in the TLV should be preceeded by this entry to indicate the
public key used.
The signature check will check each signature, and if the KEYHASH is
known and the signature type is supported, it will be checked. As long
as at least one signature is considered valid, the image will be
considered signed. This also allows the image to be signed with
multiple signatures to support having different devices with possibly
different keys compiled into the bootloaders.
Based on work by Marko Kiiskila <marko@runtime.io>
Signed-off-by: Marko Kiiskila <marko@runtime.io>
Signed-off-by: David Brown <david.brown@linaro.org>
Add a `--rust` flag to the getpub subcommand to output the public key in
Rust format rather than C.
Signed-off-by: David Brown <david.brown@linaro.org>
In preparation for moving the signature related values out of the main
image header and into the TLV, renumber the existing TLV values to be
grouped together better.
The SHA256 is moved into the first group, at 0x10, and the signature
values themselves are moved to start with 0x20.
This change is the first in a series of changes toward the new v1.0
image format. The intermediate results are all internally consistent
(meaning that the simulator, and the builtin imgtool.py will all work
together), but until all patches are applied, the image format is not
valid with any external tools.
Based on work by Marko Kiiskila <marko@runtime.io>.
Signed-off-by: Marko Kiiskila <marko@runtime.io>
Signed-off-by: David Brown <david.brown@linaro.org>
Adding an os.unlink() call to remove the outfile results in an exception
being thrown if the file does not exist. Fix this by trapping, and
checking for the specific error we get on a missing file.
Signed-off-by: David Brown <david.brown@linaro.org>
This full.bin target demonstrates how to assemble all of the images into
a single file which can be flashed to the device. As it is, it will
then boot into the first "primary" image. The second image will be
present, but will not ever be run.
Signed-off-by: David Brown <david.brown@linaro.org>
Now that script/imgtool.py contains all of the functionality of these
tools, remove the old tools from the tree. The zep2newt.py was only
able to perform a limited set of signatures. The 'imgtool' requires a
'Go' toolchain, which has been a hinderance to many users.
Please see `doc/imgtool.md` for directions on how to use this new tool
for image signing.
Signed-off-by: David Brown <david.brown@linaro.org>
The imgtool.py program has been assuming that the input image for
signing has a zero padded place for the header at the beginning of the
image. This is only true for some platforms.
Instead, make this included header space optional. By default, prepend
the header to the image. If `--included-header` is specified to the
sign command, consider the bytes at the beginning of the image to be
padded space for the header. This option is required for Zephyr builds.
If the --key is not specified, only the SHA256 hash is added to the TLV.
This is useful for testing configurations, where the crypto has not been
fully configured. Note that this configuration is not secure, and this
only verifies that the image has not been corrupted.
When parsing versions for the --version argument, allow a field to be
zero. Also, restrict the build to just an integer to match what we
allow (rather than allow alphabetic, and then failing to parse as an
integer).
In addition, add the missing import of argparse, so that when the
version is invalid, we get nice usage rather than an error about a
missing module.
Jira: MCUB-58
Changing the name of the command line argument changes the name of the
fields used to access it. Change the keysigning code to reflect this,
avoiding a stack dump when trying to generate keys.
Add support for the RSA-PSS signature algorithm to imgtool.py. This
algorithm has a strong security proof, and is recommended for all new
designs. The new algorithm is enabled by default for RSA signatures to
match the default in the bootloader also being changed.
This is the start of a python implementation of imgtool. This
implements all of the functionality that was missing in the zep2newt.py
tool, namely creation of keypairs, and converting the public version of
these keys into C code.
Add an --image-version argument to zep2newt.py to allow the major
version number to be set. This helps make testing easier by having
differing version numbers.
These are some simple scripts for signing images (with an example with a
hardcoded path), a fixed root key that matches the one checked into the
code, and a few scripts to use the Segger debugger to flash the images.
David Brown