Security features

passc tries to keep plaintext passwords and secret keys in memory for as little time as possible. Deriving the secret key uses crypto_pwhash_OPSLIMIT_MODERATE and crypto_pwhash_MEMLIMIT_MODERATE by default, which requires 256MiB of RAM and takes around 2 seconds on an M3 Pro chip. This can be increased upon creation of a passphrase. To hash the secret key (used for verification), INTERACTIVE is used. This is much faster.

sodium_mlock

Sensitive data in memory is locked using sodium_mlock. Some systems do not support this. Enabling verbose logging (-V) will show whether it is supported. This helps avoid swapping sensitive memory to disk. See libsodium's secure memory docs for more information.

sodium_memzero is always called regardless of whether sodium_mlock fails, attempting to overwrite sensitive memory after use.

Key rotation

Keys can be rotated using the rotate subcommand. This requests the current passphrase used for the vault, derives the vault's secret key, decrypts all passwords and re-encrypts them with a new passphrase. This can be used to change the hash parameters.