opentitanlib: accept ECDSA signatures as ASN.1 blobs #26010
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When processing ECDSA signatures consider the input file to be either a raw signature, with 32 bytes R and S values in little endian format concatenated into a single 64 bytes blob, or an ASN.1 encoded ECDSA signature, which is a sequence of two big endian big number values, which could be anywhere from one to 33 bytes long. In case input is in ASN .1 format Convert the values into little endian and truncate/expand as necessary to generated the internal representation of R and S of exactly 32 bytes each. Tested by attaching the Crypto4a HSM produced ECDSA signature to an owner binary image and verifying the signature, both using opentitantool. Signed-off-by: Vadim Bendebury <vbendeb@google.com>
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take two, after more thorough testing. Support processing of ECDSA signatures represented as ASN.1 DER blobs. |
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When processing ECDSA signatures consider the input file to be either a raw signature, with 32 bytes R and S values in little endian format concatenated into a single 64 bytes blob, or an ASN.1 encoded ECDSA signature, which is a sequence of two big endian big number values, which could be anywhere from one to 33 bytes long.
In case input is in ASN .1 format Convert the values into little endian and truncate/expand as necessary to generated the internal representation of R and S of exactly 32 bytes each.
Tested by attaching the Crypto4a HSM produced ECDSA signature to an owner binary image and verifying the signature, both using opentitantool.