Cell Level Encryption

Cell level encryption can do finer-grained encryption than modular encryption(Parquet-1178) or file encryption. The idea is only some fields inside the column are encrypted based on a filter expression. For example, a table with column a, b, c.x, c.y, d, we can encrypt column a, c.x where d == 5 and c.y > 0.

**Reporter**: [Xinli Shang](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=shangx@uber.com) / @shangxinli
**Assignee**: [Xinli Shang](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=shangx@uber.com) / @shangxinli
#### Externally tracked issue: [https://docs.google.com/document/d/1PUonl9i_fVlRhUmqEmWBQJ8zesX7mlvnu3ubemT11rk/edit#heading=h.kkuoyw5u0ywe](https://docs.google.com/document/d/1PUonl9i_fVlRhUmqEmWBQJ8zesX7mlvnu3ubemT11rk/edit#heading=h.kkuoyw5u0ywe)

_{**Note**: *This issue was originally created as [PARQUET-2116](https://issues.apache.org/jira/browse/PARQUET-2116). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

Iniziare con il documento di progettazione Google tracciato esternamente e il contesto di PARQUET-1178 a cui si fa riferimento nell’issue. Definire l’ambito dell’implementazione e i criteri di accettazione per la crittografia dei campi selezionati, inclusi i campi annidati, in base alle espressioni di filtro; l’issue non fornisce file del repository né test da eseguire.

Scritto dal modello di indicizzazione a partire dal testo della issue.