Attributes Overview

Tayra uses attributes to declaratively mark personal data on your model classes. At runtime, the metadata cache scans your types via reflection and drives the encryption engine automatically.

Fluent API Alternative

All attributes have fluent API equivalents that can be used instead of (or alongside) attributes. The fluent API is useful when you cannot modify the model classes directly, or when you prefer centralized configuration.

Attribute	Fluent Equivalent	Builder Options
`[DataSubjectId]`	`e.DataSubjectId(x => x.Prop)`	`.WithGroup()`, `.WithPrefix()`
`[PersonalData]`	`e.PersonalData(x => x.Prop)`	`.WithGroup()`, `.WithMaskValue()`, `.WithMaskAfter()`, `.WithMaskBefore()`, `.WithMaskEmailDomain()`, `.WithMask()`
`[DeepPersonalData]`	`e.DeepPersonalData(x => x.Prop)`	--
`[SerializedPersonalData]`	`e.SerializedPersonalData(x => x.Prop)`	`.WithGroup()`, `.StoredIn()`
`[BlindIndex]`	`e.BlindIndex(x => x.Prop)`	`.WithLowercase()`, `.WithTrim()`, `.WithTransform()`, `.StoredIn()`, `.WithScope()`, `.WithBitLength()`
`[CompoundBlindIndex]`	`e.CompoundBlindIndex("name")`	`.Field()`, `.StoredIn()`, `.WithScope()`, `.WithBitLength()`

See Fluent API for complete documentation.

Attribute Summary

Attribute	Target	Purpose
`[PersonalData]`	`string` properties	Marks a field for AES-256-GCM encryption
`[DataSubjectId]`	`Guid` or `string` properties	Identifies the data owner; derives the encryption key ID
`[DeepPersonalData]`	Class-type properties	Recurses into nested objects to encrypt their `[PersonalData]` fields
`[SerializedPersonalData]`	Non-string properties (`int`, `DateTime`, etc.)	Serializes to binary, encrypts, and stores in a companion `byte[]` field
`[BlindIndex]`	`string` properties with `[PersonalData]`	Computes an HMAC hash for equality queries on encrypted fields
`[CompoundBlindIndex]`	Classes	Combines multiple fields into a single HMAC hash for multi-field lookups

Example

Here is a typical annotated model:

public class Customer
{
    [DataSubjectId]
    public Guid Id { get; set; }

    [PersonalData]
    public string Name { get; set; } = "";

    [PersonalData(MaskValue = "redacted@example.com")]
    public string Email { get; set; } = "";

    /// <summary>
    /// Not annotated — stored and retrieved as plaintext.
    /// </summary>
    public string AccountType { get; set; } = "";
}

^anchor

In this example:

Id is the data subject identifier. Tayra derives the encryption key ID from this property's value.
Name and Email are personal data fields that will be encrypted in-place.
Email specifies a custom replacement value for after crypto-shredding.
AccountType has no annotation and is never encrypted.

How Metadata Discovery Works

When Tayra first encounters a type (via EncryptAsync<T> or DecryptAsync<T>), the PersonalDataMetadataCache scans the type using reflection:

Property scan -- All public instance properties are inspected for attributes.
Subject resolution -- Properties with [DataSubjectId] are recorded, including their group and prefix.
Field classification -- Properties with [PersonalData], [DeepPersonalData], or [SerializedPersonalData] are classified by kind: Text, Deep, Serialized, TextCollection, or DeepCollection.
Caching -- The result is stored in a ConcurrentDictionary keyed by Type. Subsequent calls for the same type return the cached metadata with no reflection overhead.

The metadata cache is thread-safe and is registered as a singleton. The reflection cost is paid only once per type for the lifetime of the application.

Roslyn Analyzers

The Tayra.Core package includes Roslyn analyzers that validate attribute usage at compile time:

Rule	Severity	Description
TAYRA001	Warning	Entity with `[PersonalData]` must have a `[DataSubjectId]` property
TAYRA002	Info	`[DataSubjectId]` without `[PersonalData]` fields is unused
TAYRA003	Error	`[DeepPersonalData]` must be on a class or record type
TAYRA004	Warning	Multiple `[DataSubjectId]` properties require `Group`
TAYRA005	Warning	`[BlindIndex]` without companion property (e.g. `EmailIndex`)
TAYRA006	Warning	`[BlindIndex]` on a non-string property

These analyzers catch common mistakes before your code runs. No separate package installation is needed.

Attributes Overview ​

Fluent API Alternative ​

Attribute Summary ​

Example ​

How Metadata Discovery Works ​

Roslyn Analyzers ​

See Also ​