The cert_create tool calculates the hash of each BL image and includes
it as an ASN.1 OCTET STRING in the corresponding certificate extension.
Without additional information, the firmware running on the platform
has to know in advance the algorithm used to generate the hash.
This patch modifies the cert_create tool so the certificate extensions
that include an image hash are generated according to the following
ASN.1 structure:
DigestInfo ::= SEQUENCE {
digestAlgorithm AlgorithmIdentifier,
digest OCTET STRING
}
AlgorithmIdentifier ::= SEQUENCE {
algorithm OBJECT IDENTIFIER,
parameters ANY DEFINED BY algorithm OPTIONAL
}
The PolarSSL module has been updated to extract the image hash
from the certificate extension according to this structure.
Change-Id: I6d83430f12a8a0eea8447bec7c936e903f644c85
This patch adds a tool that generates all the necessary elements
to establish the chain of trust (CoT) between the images.
The tool reads the binary images and signing keys and outputs the
corresponding certificates that will be used by the target at run
time to verify the authenticity of the images.
Note: the platform port must provide the file platform_oid.h. This
file will define the OIDs of the x509 extensions that will be added
to the certificates in order to establish the CoT.
Change-Id: I2734d6808b964a2107ab3a4805110698066a04be
Juan Castillo