Delineation of the Number of MT51s Required to Complete a Single OTAR for a Specific Key
| Key Level | Security Level | Public Key Length | OTAR Bit Requirement | MT51s Req. |
|---|---|---|---|---|
| 1 | 256 | 512 | 128 | 1 |
| 2 | 128 | 256 | 1280 | 10 |
| TESLA | 128 | 128 | 640 | 5 |
Note: Level-1 keys require only the 128-bit AES decryption key, hence a single MT51. Level-2 keys require 256-bit key, and 1024 bits of authenticating pseudorandom data (twice the Level-1 public key length), hence, 1280 bits and 10 MT51s. TESLA Hash Path Ends require 128-bit Hash Point and 512 bits of authenticating pseudorandom data (twice the length of the level-2 public key), hence 640 bits and 5 MT51s. Each unique MT51 is required for OTAR.