HMAC mismatch when mounting volume

[samhocevar]

I created a securefs filesystem on Windows 11 back in August, using the official 1.1.0 release, and today I can no longer mount it:

# echo "$GOODPASS" | securefs m .secrets.sfs/ .secrets
[Error] [0000000000007030] [2025-11-12 12:45:35.118788800 UTC] [int __cdecl securefs::commands_main(int,const char *const *):1466]
    class securefs::internal::InvalidHMACStreamException: HMAC mismatch
#

I tried 1.1.0 as well as the more recent 2.0.0 release, with the same results. I am using the correct password (when I don’t, the error is securefs::PasswordOrKeyfileIncorrectException). I am able to use chpass and info successfully:

# echo "$GOODPASS" | securefs i .secrets.sfs/
{
 "size_params": {
  "block_size": 4096,
  "iv_size": 12,
  "max_padding_size": 0
 },
 "full_format_params": {
  "master_key": "",
  "store_time": false,
  "legacy_file_table_io": false,
  "case_insensitive": true,
  "unicode_normalization_agnostic": false
 }
}

#

I don’t remember when the last successful mount was, but I know it did work back in August. I am not aware of any relevant changes to my system since August, except for the Windows 11 automatic updates.

Any hints on how I could debug the problem?

[netheril96]

The exception indicates that the data is corrupted. A potential cause is the Windows 11 update.