Table 3 Comparison of storage and key derivation cost
From: Comprehensive evaluation of key management hierarchies for outsourced data
Hierarchy → | User-based hierarchies | Minimal vertex | ||
|---|---|---|---|---|
| Â | User | User | Minimal vertex | resource |
↓Attributes | graph | tree | user hierarchy | hierarchy |
# of keys/users | Single | Multiple | Single | Single |
# of nodes | 2|U| + 1 | min(|R|,2|U|) + 1 | |U|+|R| | |U|+|R| |
# of edges | O(|U||U|/2) | O(min(|R|,2|U|)) | O(|U||R|) | O(|U||R|) |
key derivation cost | O(|U|) | O(|U|) | O(|U|) | O(1) |