Strategy for comparing source and destination files.
The sha1 mode compares 40-character hexadecimal SHA-1 digests as a practical drift
detector. Digest case is normalized before comparison. Missing, null, unavailable, or
non-verifiable metadata cannot prove equality: the high-level synchronizer either transfers
conservatively for untrusted metadata or skips action generation with a surfaced event when a
B2 file has no comparable digest. Untrusted B2 metadata may require downloading the selected
B2 version to hash its bytes before equality can be trusted. This is not a cryptographic
integrity or tamper-proofing guarantee, because SHA-1 collisions are possible.
Strategy for comparing source and destination files.
The
sha1mode compares 40-character hexadecimal SHA-1 digests as a practical drift detector. Digest case is normalized before comparison. Missing, null, unavailable, or non-verifiable metadata cannot prove equality: the high-level synchronizer either transfers conservatively for untrusted metadata or skips action generation with a surfaced event when a B2 file has no comparable digest. Untrusted B2 metadata may require downloading the selected B2 version to hash its bytes before equality can be trusted. This is not a cryptographic integrity or tamper-proofing guarantee, because SHA-1 collisions are possible.