The process of step "b" has multiple variations.
The following is a preferred embodiment which provides
optional steps for additional security and efficiency.


/--------------\
| Start of "b" |
\--------------/
    |
    |
    v
-------------------------------------------
| (7) Obtain a copy of the content to be  |
|     validated and store it in the cache |
-------------------------------------------
    |
    |
    v
----------------------------------------------
| (8) While the copy of the content is being |
|     obtained, recalculate its digest       |
----------------------------------------------
    |
    |
    v
-----------------------------------------------------
| (9) Store the recalculated digest as a key for    |
|     association with the cached content for later |
|     retrieval                                     |
-----------------------------------------------------
    |
    |
    v
/------------\
| End of "b" |
\------------/