Public keys should be stored as sub-nodes in a /signature node. Required
properties are:
-- algo: Algorithm name (e.g. "sha1,rsa2048")
+- algo: Algorithm name (e.g. "sha1,rsa2048" or "sha256,ecdsa256")
Optional properties are:
- rsa,r-squared: (2^num-bits)^2 as a big-endian multi-word integer
- rsa,n0-inverse: -1 / modulus[0] mod 2^32
+For ECDSA the following are mandatory:
+- ecdsa,curve: Name of ECDSA curve (e.g. "prime256v1")
+- ecdsa,x-point: Public key X coordinate as a big-endian multi-word integer
+- ecdsa,y-point: Public key Y coordinate as a big-endian multi-word integer
+
+These parameters can be added to a binary device tree using parameter -K of the
+mkimage command::
+
+ tools/mkimage -f fit.its -K control.dtb -k keys -r image.fit
+
+Here is an example of a generated device tree node::
+
+ signature {
+ key-dev {
+ required = "conf";
+ algo = "sha256,rsa2048";
+ rsa,r-squared = <0xb76d1acf 0xa1763ca5 0xeb2f126
+ 0x742edc80 0xd3f42177 0x9741d9d9
+ 0x35bb476e 0xff41c718 0xd3801430
+ 0xf22537cb 0xa7e79960 0xae32a043
+ 0x7da1427a 0x341d6492 0x3c2762f5
+ 0xaac04726 0x5b262d96 0xf984e86d
+ 0xb99443c7 0x17080c33 0x940f6892
+ 0xd57a95d1 0x6ea7b691 0xc5038fa8
+ 0x6bb48a6e 0x73f1b1ea 0x37160841
+ 0xe05715ce 0xa7c45bbd 0x690d82d5
+ 0x99c2454c 0x6ff117b3 0xd830683b
+ 0x3f81c9cf 0x1ca38a91 0x0c3392e4
+ 0xd817c625 0x7b8e9a24 0x175b89ea
+ 0xad79f3dc 0x4d50d7b4 0x9d4e90f8
+ 0xad9e2939 0xc165d6a4 0x0ada7e1b
+ 0xfb1bf495 0xfc3131c2 0xb8c6e604
+ 0xc2761124 0xf63de4a6 0x0e9565f9
+ 0xc8e53761 0x7e7a37a5 0xe99dcdae
+ 0x9aff7e1e 0xbd44b13d 0x6b0e6aa4
+ 0x038907e4 0x8e0d6850 0xef51bc20
+ 0xf73c94af 0x88bea7b1 0xcbbb1b30
+ 0xd024b7f3>;
+ rsa,modulus = <0xc0711d6cb 0x9e86db7f 0x45986dbe
+ 0x023f1e8c9 0xe1a4c4d0 0x8a0dfdc9
+ 0x023ba0c48 0x06815f6a 0x5caa0654
+ 0x07078c4b7 0x3d154853 0x40729023
+ 0x0b007c8fe 0x5a3647e5 0x23b41e20
+ 0x024720591 0x66915305 0x0e0b29b0
+ 0x0de2ad30d 0x8589430f 0xb1590325
+ 0x0fb9f5d5e 0x9eba752a 0xd88e6de9
+ 0x056b3dcc6 0x9a6b8e61 0x6784f61f
+ 0x000f39c21 0x5eec6b33 0xd78e4f78
+ 0x0921a305f 0xaa2cc27e 0x1ca917af
+ 0x06e1134f4 0xd48cac77 0x4e914d07
+ 0x0f707aa5a 0x0d141f41 0x84677f1d
+ 0x0ad47a049 0x028aedb6 0xd5536fcf
+ 0x03fef1e4f 0x133a03d2 0xfd7a750a
+ 0x0f9159732 0xd207812e 0x6a807375
+ 0x06434230d 0xc8e22dad 0x9f29b3d6
+ 0x07c44ac2b 0xfa2aad88 0xe2429504
+ 0x041febd41 0x85d0d142 0x7b194d65
+ 0x06e5d55ea 0x41116961 0xf3181dde
+ 0x068bf5fbc 0x3dd82047 0x00ee647e
+ 0x0d7a44ab3>;
+ rsa,exponent = <0x00 0x10001>;
+ rsa,n0-inverse = <0xb3928b85>;
+ rsa,num-bits = <0x800>;
+ key-name-hint = "dev";
+ };
+ };
+
Signed Configurations
---------------------
data = <data for fdt1>;
signature-1 {
algo = "sha1,rsa2048";
- vaue = <...fdt signature 1...>
+ value = <...fdt signature 1...>
};
};
fdt-2 {
data = <data for fdt2>;
signature-1 {
algo = "sha1,rsa2048";
- vaue = <...fdt signature 2...>
+ value = <...fdt signature 2...>
};
};
};
kernel = "kernel-1";
fdt = "fdt-1";
};
- conf-1 {
+ conf-2 {
kernel = "kernel-2";
fdt = "fdt-2";
};
kernel = "kernel-1";
fdt = "fdt-1";
};
- conf-1 {
+ conf-2 {
kernel = "kernel-2";
fdt = "fdt-2";
};
This happens automatically as part of a bootm command when FITs are used.
+For Signed Configurations, the default verification behavior can be changed by
+the following optional property in /signature node in U-Boot's control FDT.
+
+- required-mode: Valid values are "any" to allow verified boot to succeed if
+the selected configuration is signed by any of the 'required' keys, and "all"
+to allow verified boot to succeed if the selected configuration is signed by
+all of the 'required' keys.
+
+This property can be added to a binary device tree using fdtput as shown in
+below examples::
+
+ fdtput -t s control.dtb /signature required-mode any
+ fdtput -t s control.dtb /signature required-mode all
+
Enabling FIT Verification
-------------------------
WARNING: When relying on signed FIT images with required signature check
the legacy image format is default disabled by not defining
-CONFIG_IMAGE_FORMAT_LEGACY
+CONFIG_LEGACY_IMAGE_FORMAT
+
Testing
-------
$ make O=sandbox sandbox_config
$ make O=sandbox
$ O=sandbox ./test/vboot/vboot_test.sh
+
+
Simple Verified Boot Test
=========================
Test passed
-Hardware Signing with PKCS#11
------------------------------
+Software signing: keydir vs keyfile
+-----------------------------------
+
+In the simplest case, signing is done by giving mkimage the 'keyfile'. This is
+the path to a file containing the signing key.
+
+The alternative is to pass the 'keydir' argument. In this case the filename of
+the key is derived from the 'keydir' and the "key-name-hint" property in the
+FIT. In this case the "key-name-hint" property is mandatory, and the key must
+exist in "<keydir>/<key-name-hint>.<ext>" Here the extension "ext" is
+specific to the signing algorithm.
+
+
+Hardware Signing with PKCS#11 or with HSM
+-----------------------------------------
Securely managing private signing keys can challenging, especially when the
keys are stored on the file system of a computer that is connected to the
device.
Requirements:
-Smartcard/USB token/HSM which can work with the pkcs11 engine
+Smartcard/USB token/HSM which can work with some openssl engine
openssl
+
+For pkcs11 engine usage:
libp11 (provides pkcs11 engine)
p11-kit (recommended to simplify setup)
opensc (for smartcards and smartcard like USB devices)
gnutls (recommended for key generation, p11tool)
-The following examples use the Nitrokey Pro. Instructions for other devices may vary.
+For generic HSMs respective openssl engine must be installed and locateable by
+openssl. This may require setting up LD_LIBRARY_PATH if engine is not installed
+to openssl's default search paths.
+
+PKCS11 engine support forms "key id" based on "keydir" and with
+"key-name-hint". "key-name-hint" is used as "object" name (if not defined in
+keydir). "keydir" (if defined) is used to define (prefix for) which PKCS11 source
+is being used for lookup up for the key.
+
+PKCS11 engine key ids:
+ "pkcs11:<keydir>;object=<key-name-hint>;type=<public|private>"
+or, if keydir contains "object="
+ "pkcs11:<keydir>;type=<public|private>"
+or
+ "pkcs11:object=<key-name-hint>;type=<public|private>",
+
+Generic HSM engine support forms "key id" based on "keydir" and with
+"key-name-hint". If "keydir" is specified for mkimage it is used as a prefix in
+"key id" and is appended with "key-name-hint".
+
+Generic engine key ids:
+ "<keydir><key-name-hint>"
+or
+ "<key-name-hint>"
+
+In order to set the pin in the HSM, an environment variable "MKIMAGE_SIGN_PIN"
+can be specified.
+
+The following examples use the Nitrokey Pro using pkcs11 engine. Instructions
+for other devices may vary.
Notes on pkcs11 engine setup:
projects / platform / kernel / u-boot.git / blobdiff