The table below defines the associated data as it is stored in the ECC token in the clear. Associated data is data whose integrity but not confidentiality is protected by a key wrap mechanism.
| Offset (Dec) | Number of Bytes | Description |
|---|---|---|
| 000 | 001 | Associated Data Version. 0 for ECC |
| 001 | 001 | Length of Key Label, kl |
| 002 | 002 | IBM Associated Data length, 16 + kl + xxx |
| 004 | 002 | IBM Extended Associated Data length, xxx |
| 006 | 001 | User Definable Associated Data length, yyy. User definable lengths are from 0 bytes to 100 bytes. |
| 007 | 001 | Curve Type |
| 008 | 002 | Length of p in bits |
| 010 | 001 | Usage flag |
| 011 | 001 | Format and Security flag |
| 012 | 004 | reserved |
| 016 | kl | Key Label (optional) |
| 016 + kl | xxx | IBM Extended Associated Data |
| 016 + kl + xxx | yyy | User-definable Associated Data |