Task 6.3: Apply anonymization and pseudonymization methods — such as hashing, tokenization, suppression, and generalization — to confidential data (e.g., using column masks and related Unity Catalog features).

• Asha2(email, 256), applied identically in every table and every load

  Incorrect

  An unkeyed hash is consistent, but anyone can hash known emails and match the results.

• Bmask(email), the built-in masking function

  Incorrect

  Masking replaces letters and digits with placeholders, so different emails collide and the value no longer works as a join key.

• Cuuid(), generated for each row at load time

  Incorrect

  A random value per load changes between loads and tables, so joins break.

• Dhex(hmac(secret key, email)) with a key from a secret scope

  Correct

  A keyed hash gives the same value for the same email, and without the secret key nobody can recompute it from candidate emails.

hmac computes a keyed hash with a secret key, so values are consistent but cannot be reproduced without the key. sha2 alone is unkeyed, mask replaces characters, and random values are not stable across loads.

• AGeneralization, with a column mask that returns only the year

  Correct

  Generalization replaces a value with a coarser one, and a column mask can return it based on group membership.

• BSuppression, with a column mask that returns NULL for analysts

  Incorrect

  Suppression hides the value entirely, losing the age band.

• CTokenization, replacing each date with a random token per row

  Incorrect

  A token hides the value but keeps no age information.

• DEncryption of the date with aes_encrypt for the analysts

  Incorrect

  Ciphertext keeps no usable age information for analysts.

Column masks are SQL UDFs that return a value per row based on the querying user. Returning a coarser value, such as the year, generalizes the data for some groups while others see the full value.

• ACASE WHEN is_account_group_member('payroll') THEN ssn ELSE mask(ssn) END

  Incorrect

  A partly masked string still exposes the shape of the value.

• Bsha2(ssn, 256) for everyone

  Incorrect

  Payroll would lose the real value, and hashes can be matched.

• CCASE WHEN current_user() = 'payroll' THEN ssn ELSE NULL END

  Incorrect

  current_user() returns a user, not a group name.

• DCASE WHEN is_account_group_member('payroll') THEN ssn ELSE NULL END

  Correct

  Returning NULL for others suppresses the value entirely.

A column mask function receives the column value and returns what each user sees. Checking group membership with is_account_group_member and returning NULL otherwise suppresses the value.

• A'XX-XX'

  Incorrect

  Each class has its own default replacement character.

• B'Xx-nn'

  Correct

  Upper case becomes X, lower case x and digits n; other characters stay as they are by default.

• C'*****'

  Incorrect

  The default does not use asterisks or mask the separator.

• DNULL

  Incorrect

  mask returns a masked string, not NULL.

mask(str) replaces upper-case letters with X, lower-case letters with x and digits with n. Other characters are left unmasked unless otherChar is given.

• Asha2(account_number, 512), with the hash stored instead of the number

  Incorrect

  A hash cannot be reversed to the original number.

• Bmask(account_number), with the masked value stored instead

  Incorrect

  Masking discards the original digits.

• Caes_encrypt with a secret-scope key; the fraud team uses aes_decrypt

  Correct

  AES encryption is reversible for whoever holds the key.

• DA column mask that returns NULL on every read

  Incorrect

  NULL keeps no recoverable value.

Encryption with aes_encrypt is reversible with aes_decrypt and the same key, which should be kept in a secret scope. Hashing and masking are one way.