Support signing payload with 4096 bits RSA keys

The 32 bytes sha256 hash was padded to 256 bytes before payload signing
and verification. During the padding, we appended a hard coded header
according to RFC3447 spec.

As we want to support signing with 4096 bits keys, the format of the
padding doesn't change but the length needs adjustion. Now callers will
pass in the RSA size in bytes in the padding function. And the
verification function will now take the raw 32 bytes sha256 hash instead
of the padded value.

The new key for unittest is generated by:
openssl genrsa -out unittest_key_RSA4096.pem 4096

Bug: 129163830
Test: unit tests pass, create and install an update signed by 4096 bits key.
Change-Id: I8e0d02ddb1472e22976c0f170e8bf2b8b094c7d4

0 files changed, 0 insertions, 0 deletions