KEY_BITS replaces UNSPEC which caused internal implementation problems. It is used by a redesigned KID {(kid)} to provide economical identification of keys.

KEY_BITS(0;K==>c,((4,v),(n,kbits));) returns kbits, a value that depends on the key K. Different keys that exist in slots at one time produce different kbits values.

n will probably never exceed 16 bytes.

v will grow at most a few per week.

If the first call preceeded the second call then v1 <= v2.

If v1=v2 then n1=n2 and (if K1=K2 then kb1=kb2) and (if kb1 = kb2 then K1=K2 or K1 = dk(0) or K2 = dk(0)).