SilcIDCacheEntry
    silc_idcache_add(SilcIDCache cache, char *name, void *id, void *context);

    Add new entry to the cache.  Returns the allocated cache entry if the
    entry was added successfully, or NULL if error occurred.  The `name' is
    the name associated with the ID, the `id' the actual ID and the
    `context' a caller specific context.  The caller is responsible of
    freeing the `name' and `id' when the entry is deleted.