In V2 version each file encrypted using separate CEK (wrapped with AES Keywrap RFC3394). Truncation protection uses last byte of nonce to indicate last encryption block.
Added MD5 hash support for crypt.go (only if V2 cipher is used), MD5 of plaintext is encrypted and authenticated at the end of file.
Added 4 reserved bytes at the beginning for future use.
Added 1 hash type byte in the footer to allow upgrade to different than MD5 hash.
cipher_version setting determines hash version used for writes.
For reads we determine cipher version by reading header magic bytes, that's regardless of cipher_version setting. A
Added TestNewEncrypterV2 test to demonstrate the outputs and make sure that outputs match the expected hardcoded values.
Modified other tests to satisfy newly added params (e.g. cek).
Related to: https://github.com/rclone/rclone/issues/7192