:sig
bool password_needs_rehash(String encoded)

:params
encoded : stored password credential
return value : true when the encoding is malformed or does not use UCE's current parameters

:content
Checks whether a stored UCE password encoding should be replaced. Call it only after successful verification, then hash the known-correct password again and atomically replace the old credential. Non-UCE legacy formats are reported as needing rehash but must be verified by the application before upgrade.

:example
String old = "$uce$scrypt$16384$8$1$00112233445566778899aabbccddeeff$29fdfb3d991961e926a19c1136a07e252afa5fdb8d3a0fb74cdcfa5016956f34";
print(password_verify("legacy password", old) && password_needs_rehash(old) ? "upgrade" : "keep", "\n");

:see
>sys
password_hash
password_verify