Some platforms prefer images in the Intel Hex (.hex) format. Implement
support for signing images in this format in imgtool.
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
Until we fix the padding problem, pad the ecdsa signatures with zeros to
always be 72 bytes long. Add a 'raw_sign' method so that the unit test
can use the real signature.
Signed-off-by: David Brown <david.brown@linaro.org>
Replace the (now broken) ECDSA code with code using the python
'cryptography' library.
Similar to the change to RSA, this changes the format that private keys
are stored, again using PKCS#8. This supports the stronger password
protection as well.
Again, this code will still support reading the older style of public
keys, but other tools that use keys generated by this change will need
to be updated to work with the new format.
Signed-off-by: David Brown <david.brown@linaro.org>
The verification code requires a fixed 32-byte salt, which seems is what
the old crypto library did. Use this same value to avoid having to
modify the code.
Signed-off-by: David Brown <david.brown@linaro.org>
The keygen command allows the `-p` argument which will prompt for a
password, and protect the private key with this password. When loading
keys, it will prompt for a password if it detects a password protected
key.
Signed-off-by: David Brown <david.brown@linaro.org>
The 'cryptography' library is pickier about the data it is asked to
sign. Get the bytes value out of the bytearray for doing the actual
signature.
Signed-off-by: David Brown <david.brown@linaro.org>
Replace RSA code with one using the python 'cryptography' library. This
library is much more complete, and will make adding support for password
protected keys, and separate public keys easier.
There is, however, a significant change brought about by this change:
the private keys are stored in PKCS#8 format, instead of the raw format
that was used previously. This is a more modern format that has a few
advantages, including: supporting stronger password protection, and
allowing the key type to be determined upon read.
This tool will still support reading the old style public keys, but
other tools that use these keys will need to be updated in order to work
with the new format.
This new code has some unit tests to go along with it for some basic
sanity testing of the code.
Signed-off-by: David Brown <david.brown@linaro.org>
Although these files are likely implicitly licensed under the Apache 2.0
license because of the LICENSE file for this project, make this explicit
in these files.
Signed-off-by: David Brown <david.brown@linaro.org>
Earlier refactoring created a call for get_public_bytes() that was added
to the RSA class, but missed on the ECDSA class. Add this call so that
ECDSA signatures will work again.
Signed-off-by: David Brown <david.brown@linaro.org>
Since we've changed the meaning of several fields in the header, bump
the header to a new magic number. The fields that are still present are
in the same place, but all of the signature and TLV information is moved
into the TLV itself, which is still immediately after the image.
As of this commit, this defines the new image header/TLV format used for
1.0.
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>
To allow the signatures to be replaced, move the size of the TLV into a
small "info" header at the start of the TLV.
Note that this causes image swapping to lose robustness. This is fixed
by a later commit.
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>
JIRA: MCUB-65
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>
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
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.
Carles Cufi