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Diffstat (limited to 'doc/usage/fit/source_file_format.rst')
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1 files changed, 146 insertions, 1 deletions
diff --git a/doc/usage/fit/source_file_format.rst b/doc/usage/fit/source_file_format.rst index f1cc1bc..1f6c338 100644 --- a/doc/usage/fit/source_file_format.rst +++ b/doc/usage/fit/source_file_format.rst @@ -385,6 +385,10 @@ hash-1 Each hash sub-node represents separate hash or checksum calculated for node's data according to specified algorithm. +signature-1 + Each signature sub-node represents separate signature + calculated for node's data according to specified algorithm. + Hash nodes ---------- @@ -418,6 +422,91 @@ algo value Actual checksum or hash value. +Image-signature nodes +--------------------- + +:: + + o signature-1 + |- algo = "algorithm name" + |- key-name-hint = "key name" + |- value = [hash or checksum value] + + +Mandatory properties +~~~~~~~~~~~~~~~~~~~~ + +_`FIT Algorithm`: + +algo + Algorithm name. Supported algoriths and their value sizes are shown below. + Note that the hash is specified separately from the signing algorithm, so + it is possible to mix and match any SHA algorithm with any signing + algorithm. The size of the signature relates to the signing algorithm, not + the hash, since it is the hash that is signed. + + ==================== ============ ========================================= + Sub-image type Size (bytes) Meaning + ==================== ============ ========================================= + sha1,rsa2048 256 SHA1 hash signed with 2048-bit + Rivest–Shamir–Adleman algorithm + sha1,rsa3072 384 SHA1 hash signed with 2048-bit RSA + sha1,rsa4096 512 SHA1 hash signed with 2048-bit RSA + sha1,ecdsa256 32 SHA1 hash signed with 256-bit Elliptic + Curve Digital Signature Algorithm + sha256,... + sha384,... + sha512,... + ==================== ============ ========================================= + +key-name-hint + Name of key to use for signing. The keys will normally be in + a single directory (parameter -k to mkimage). For a given key <name>, its + private key is stored in <name>.key and the certificate is stored in + <name>.crt. + +sign-images + A list of images to sign, each being a property of the conf + node that contains then. The default is "kernel,fdt" which means that these + two images will be looked up in the config and signed if present. This is + used by mkimage to determine which images to sign. + +The following properies are added as part of signing, and are mandatory: + +value + Actual signature value. This is added by mkimage. + +hashed-nodes + A list of nodes which were hashed by the signer. Each is + a string - the full path to node. A typical value might be:: + + hashed-nodes = "/", "/configurations/conf-1", "/images/kernel", + "/images/kernel/hash-1", "/images/fdt-1", + "/images/fdt-1/hash-1"; + +hashed-strings + The start and size of the string region of the FIT that was hashed. The + start is normally 0, indicating the first byte of the string table. The size + indicates the number of bytes hashed as part of signing. + +The following properies are added as part of signing, and are optional: + +timestamp + Time when image was signed (standard Unix time_t format) + +signer-name + Name of the signer (e.g. "mkimage") + +signer-version + Version string of the signer (e.g. "2013.01") + +comment + Additional information about the signer or image + +padding + The padding algorithm, it may be pkcs-1.5 or pss, + if no value is provided we assume pkcs-1.5 + '/configurations' node ---------------------- @@ -447,6 +536,13 @@ Mandatory nodes configuration-sub-node-unit-name At least one of the configuration sub-nodes is required. +Optional nodes +~~~~~~~~~~~~~~ + +signature-1 + Each signature sub-node represents separate signature + calculated for the configuration according to specified algorithm. + Configuration nodes ------------------- @@ -460,7 +556,7 @@ Each configuration has the following structure:: |- loadables = "loadables sub-node unit-name" |- script = " |- compatible = "vendor,board-style device tree compatible string" - + o signature-1 {...} Mandatory properties ~~~~~~~~~~~~~~~~~~~~ @@ -512,6 +608,55 @@ Older, 2.4 kernel and 2.6 non-FDT kernel do not use FDT blob, in such cases 'struct bd_info' must be passed instead of FDT blob, thus fdt property *must not* be specified in a configuration node. +Configuration-signature nodes +----------------------------- + +:: + + o signature-1 + |- algo = "algorithm name" + |- key-name-hint = "key name" + |- sign-images = "path1", "path2"; + |- value = [hash or checksum value] + |- hashed-strings = <0 len> + + +Mandatory properties +~~~~~~~~~~~~~~~~~~~~ + +algo + See `FIT Algorithm`_. + +key-name-hint + Name of key to use for signing. The keys will normally be in + a single directory (parameter -k to mkimage). For a given key <name>, its + private key is stored in <name>.key and the certificate is stored in + <name>.crt. + +The following properies are added as part of signing, and are mandatory: + +value + Actual signature value. This is added by mkimage. + +The following properies are added as part of signing, and are optional: + +timestamp + Time when image was signed (standard Unix time_t format) + +signer-name + Name of the signer (e.g. "mkimage") + +signer-version + Version string of the signer (e.g. "2013.01") + +comment + Additional information about the signer or image + +padding + The padding algorithm, it may be pkcs-1.5 or pss, + if no value is provided we assume pkcs-1.5 + + Examples -------- |