Design+impl: encrypted field annotations (for things like PII, etc.) on structs?

[alecthomas]

• Could also be a custom FTL type like ftl.Optional but instead ftl.Encrypted. That might have a Decrypt() func that could be used to get the underlying value explicitly when needed.
• Possibly add semantic type annotations to fields (compatible with https://prototype.sqprod.co/#/packages/squareup.governance.v0)
• Challenge, can we keep sensitive data encrypted as long as possible while processing it through FTL. Require explicit Decrypt or “Access” calls to retrieve plaintext.
• Ideally this should extend down to the database layer where possible, eg. types that represent that a field is encrypted, etc.
• Can we support Tink's associated data concept?

[alecthomas]

Challenge, can we keep sensitive data encrypted as long as possible while processing it through FTL. Require explicit Decrypt or “Access” calls to retrieve plaintext.

@AlexSzlavik we can do this (it's how FTL is doing it currently), but the ergonomics are pretty painful (in Go in particular) because of the need to check decryption/encryption errors on every field access.