hs-v3: Simplify decrypt_desc_layer interface
Here is how
decrypt_desc_layer is called:
superencrypted_len = decrypt_desc_layer(desc, desc->plaintext_data.superencrypted_blob, desc->plaintext_data.superencrypted_blob_size, NULL, 1, &superencrypted_plaintext);
encrypted_len = decrypt_desc_layer(desc, desc->superencrypted_data.encrypted_blob, desc->superencrypted_data.encrypted_blob_size, descriptor_cookie, 0, &encrypted_plaintext);
There is no point in passing
desc->superencrypted_data.encrypted_blob_size since we are already passing the whole
is_superencrypted_layer which should be enough to figure out which fields to use.
We could either of the following two things:
descas an argument and pass
encrypted_blob_sizeas arguments and get them off desc.
I prefer the first, but I'm fine with either, since it will make the interface cleaner.