Anvil.PII.Redactor (Anvil v0.1.1)

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Redaction strategies for PII fields during export.

This module applies various redaction policies to field values to protect sensitive information while preserving analytical value.

Redaction Strategies

  • :preserve - Keep field unchanged (explicit opt-in)
  • :strip - Remove field entirely (returns nil)
  • :truncate - Truncate to first N characters
  • :hash - Hash value (preserves uniqueness for grouping)
  • :regex_redact - Apply regex-based redaction patterns

Examples

iex> Anvil.PII.Redactor.redact("sensitive text", :strip)
nil

iex> Anvil.PII.Redactor.redact("long text here", :truncate, max_length: 10)
"long text "

iex> Anvil.PII.Redactor.redact("test@example.com", :hash)
"a7b2c3..." # SHA256 hash

Summary

Types

redaction_opts()
redaction_policy()

Functions

default_patterns()

Returns the default PII detection patterns.

detect_pii(value)

Detects potential PII in a string value using regex patterns.

redact(value, policy, opts \\ [])

Applies a redaction policy to a field value.

redact_payload(payload, field_metadata_map, redaction_mode, opts \\ [])

Redacts a map of field values based on field metadata.

Types

redaction_opts()

@type redaction_opts() :: keyword()

redaction_policy()

@type redaction_policy() :: :preserve | :strip | :truncate | :hash | :regex_redact

Functions

default_patterns()

@spec default_patterns() :: [{Regex.t(), String.t()}]

Returns the default PII detection patterns.

Each pattern is a tuple of {regex, replacement_text}.

detect_pii(value)

@spec detect_pii(String.t()) :: [atom()]

Detects potential PII in a string value using regex patterns.

Returns a list of detected PII types.

Examples

iex> Anvil.PII.Redactor.detect_pii("Contact me at test@example.com")
[:email]

iex> Anvil.PII.Redactor.detect_pii("Call 555-123-4567")
[:phone]

iex> Anvil.PII.Redactor.detect_pii("No PII here")
[]

redact(value, policy, opts \\ [])

@spec redact(any(), redaction_policy(), redaction_opts()) :: any()

Applies a redaction policy to a field value.

Options

  • :max_length - Maximum length for :truncate policy (default: 100)
  • :patterns - List of {regex, replacement} tuples for :regex_redact (default: common PII patterns)
  • :salt - Salt for hashing (default: nil)

Examples

iex> Anvil.PII.Redactor.redact("value", :preserve)
"value"

iex> Anvil.PII.Redactor.redact("value", :strip)
nil

iex> Anvil.PII.Redactor.redact("long text", :truncate, max_length: 4)
"long"

iex> Anvil.PII.Redactor.redact("test", :hash)
"9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08"

redact_payload(payload, field_metadata_map, redaction_mode, opts \\ [])

@spec redact_payload(map(), map(), :none | :automatic | :aggressive, keyword()) ::
  map()

Redacts a map of field values based on field metadata.

Parameters

  • payload - Map of field names to values
  • field_metadata_map - Map of field names to metadata maps
  • redaction_mode - Redaction mode (:none, :automatic, :aggressive)
  • opts - Additional options passed to redaction functions

Examples

iex> payload = %{"name" => "John", "age" => 30}
iex> metadata = %{
...>   "name" => %{pii: :definite, redaction_policy: :strip},
...>   "age" => %{pii: :none}
...> }
iex> Anvil.PII.Redactor.redact_payload(payload, metadata, :automatic)
%{"age" => 30}