Dirk Petersen a7759387d6 hash: add CRC-32C (Castagnoli) support ...

Add the hash type crc32c. It is the checksum that AWS S3 stores for
objects uploaded with x-amz-checksum-crc32c (FULL_OBJECT checksum),
and the checksum that iSCSI, ext4 and Btrfs use. Go calculates it with
the SSE 4.2 and ARMv8 CRC32 instructions where they are available.

With it, rclone can calculate the value that S3 returns in
ChecksumCRC32C for a local file:

    rclone hashsum crc32c file

prints it as hex; `--base64` prints it in the URL-safe base64 alphabet
that rclone uses for every hash (`-` and `_` where S3 prints `+` and
`/`).

The new type is registered after the existing core types, so their
Type values do not change. The types that backends register (dropbox,
hidrive, mailru, quickxor) move up one bit, as they did when blake3,
xxh3 and xxh128 were added; no Type value is persisted (the hasher
cache and bisync listings store hash names).

2026-10-27 14:40:02 +00:00

..

hash_test.go

hash: add CRC-32C (Castagnoli) support

2026-10-27 14:40:02 +00:00

hash.go

hash: add CRC-32C (Castagnoli) support

2026-10-27 14:40:02 +00:00