The following SQL statement enables to generate a base64 uuid encoded on 96bits (12 octects).
SELECT (substr(chars, (first & 63)+1, 1) ||
substr(chars, ((first >> 6) & 63)+1, 1) ||
substr(chars, ((first >> 12) & 63)+1, 1) ||
substr(chars, ((first >> 18) & 63)+1, 1) ||
substr(chars, ((first >> 24) & 63)+1, 1) ||
substr(chars, ((first >> 30) & 63)+1, 1) ||
substr(chars, ((first >> 36) & 63)+1, 1) ||