docs/design/auth-framework.rst

9    terms of certificate hierarchy and the mechanisms used to verify a
14    -  The mechanism used to encode and transport information, e.g. DER encoded
18    -  The mechanism used to verify the transported information i.e. the
142 #. Authenticate the image as per the cryptographic algorithms used.
145    be used to authenticate the next image in the CoT.
167    also specifies the authentication methods and the parsing method used for
171    used for verifying the CoT, e.g. memory for public keys, hashes etc.
188 #. Export a custom IPM if a proprietary image format is being used (described
245                             /* SHA256, SHA384 and SHA512 can be used. */
282 ``_name`` must be a string containing the name of the CL. This name is used for
285 The ``_init`` function is used to perform any initialization required for
288 The ``_verify_signature`` function is used to verify certificates,
289 and ``_verify_hash`` is used to verify raw images.
291 The ``_calc_hash`` function is mainly used in the ``MEASURED_BOOT``
296 of encrypted data. This function is used when the optional encrypted
302 (_convert_pk). It is only used if the platform saves a hash of the ROTPK.
305 Defining this function allows to transform the ROTPK used to verify
326 #. Extracting parameters used for authenticating an image based upon a
332 used in the CoT. This library must implement the specific methods to parse the
374    type of hash algorithm used as this information accompanies the hash. This
437 single parsing method. There has to be one IPL for every method used by the
441    is treated as being in raw binary format e.g. boot loader images used by
442    TF-A. This method should only be used by data images.
446    libraries will be available which can be used to parse an image represented
447    by this method. Such libraries can be used to write the corresponding IPL
457 The following enum can be used to define these three methods.
490 The ``init()`` function will be used to initialize the IPL.
501 be used to verify either the current or the next image in the CoT sequence.
504 will be used by the IPM to find the right parser descriptor for the image.
510 which will be used to verify it. As described in the Section "Authentication
522 The AM defines the type of each parameter used by an authentication method. It
557 ``cookie`` is used by the platform to specify additional information to the IPM
564 the ``cookie`` field means that it is not used.
629 field is used to specify the length of the data in the memory.
636 parameters that should be extracted from it and used to verify the next image
656 #. A parsing method which is used by the AM to find the appropriate IPM.
659    section. These are used to verify the current image.
661 #. Parameters which are used to verify the next image in the current CoT. These
693 and ``drivers/auth/tbbr/tbbr_cot_bl2.c`` respectively. The common CoT used across
768       -  ``alg``: the signature algorithm used (obtained from current image)
784 be used to extract the parameter data from the corresponding image.
929    is used to extract a public key from the parent image. If the cookie is an
934 -  ``sig``: parameter descriptor of type ``AUTH_PARAM_SIG``. It is used to extract
936 -  ``sig_alg``: parameter descriptor of type ``AUTH_PARAM_SIG``. It is used to
938 -  ``raw_data``: parameter descriptor of type ``AUTH_PARAM_RAW_DATA``. It is used
946 descriptor is used to extract the public key from an x509v3 extension with OID
977 depend on the images used in the CoT. Raw images do not need a library, so