diff options
Diffstat (limited to 'doc/uImage.FIT/signature.txt')
| -rw-r--r-- | doc/uImage.FIT/signature.txt | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/doc/uImage.FIT/signature.txt b/doc/uImage.FIT/signature.txt index c71280b63b..21eb3894aa 100644 --- a/doc/uImage.FIT/signature.txt +++ b/doc/uImage.FIT/signature.txt @@ -42,8 +42,8 @@ device. Algorithms ---------- In principle any suitable algorithm can be used to sign and verify a hash. -At present only one class of algorithms is supported: SHA1 hashing with RSA. -This works by hashing the image to produce a 20-byte hash. +U-Boot supports a few hashing and verification algorithms. See below for +details. While it is acceptable to bring in large cryptographic libraries such as openssl on the host side (e.g. mkimage), it is not desirable for U-Boot. @@ -56,10 +56,10 @@ of data from the FDT and exponentiation mod n. Code size impact is a little under 5KB on Tegra Seaboard, for example. It is relatively straightforward to add new algorithms if required. If -another RSA variant is needed, then it can be added to the table in -image-sig.c. If another algorithm is needed (such as DSA) then it can be -placed alongside rsa.c, and its functions added to the table in image-sig.c -also. +another RSA variant is needed, then it can be added with the +U_BOOT_CRYPTO_ALGO() macro. If another algorithm is needed (such as DSA) then +it can be placed in a directory alongside lib/rsa/, and its functions added +using U_BOOT_CRYPTO_ALGO(). Creating an RSA key pair and certificate @@ -439,6 +439,7 @@ be enabled: CONFIG_FIT_SIGNATURE - enable signing and verification in FITs CONFIG_RSA - enable RSA algorithm for signing +CONFIG_ECDSA - enable ECDSA algorithm for signing WARNING: When relying on signed FIT images with required signature check the legacy image format is default disabled by not defining @@ -694,8 +695,6 @@ bootm. Possible Future Work -------------------- -- Add support for other RSA/SHA variants, such as rsa4096,sha512. -- Other algorithms besides RSA - More sandbox tests for failure modes - Passwords for keys/certificates - Perhaps implement OAEP |