Class AesGcmEnvelope

Namespace

MailFathom.Common

Assembly

MailFathom.Common.dll

Seals a value with AES-256-GCM so that reading where it is stored does not disclose it.

public static class AesGcmEnvelope

Inheritance

object

AesGcmEnvelope

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Remarks

The sealed form is nonce ‖ tag ‖ ciphertext: a fresh 96-bit nonce, the 128-bit authentication tag, and the ciphertext, in that order and in one buffer. The layout is fixed rather than configurable, because a reader has to be able to open a value written by an older build.

Every operation takes associated data, which is authenticated but not encrypted. It is what binds a sealed value to where it belongs — a credential to its endpoint, a column value to its row — so a value moved somewhere else fails to open instead of quietly decrypting under the wrong meaning. There is no overload without it: a caller with nothing to bind is a caller who has not yet worked out what the value is for.

This type holds no key. It is handed one and forgets it, which is deliberate: where a key comes from, how long it lives, and what protects it at rest differ per consumer, and folding a single answer in here would give two consumers with different threat models the weaker of the two.

Fields

KeySizeInBytes

The key length this envelope uses, in bytes.

Methods

CreateKey()

Generates a key of the length this envelope expects.

Open(ReadOnlySpan<byte>, ReadOnlySpan<byte>, ReadOnlySpan<byte>)

Opens a sealed value.

OpenText(ReadOnlySpan<byte>, string, string)

Opens text sealed by SealText(ReadOnlySpan<byte>, string, string).

Seal(ReadOnlySpan<byte>, ReadOnlySpan<byte>, ReadOnlySpan<byte>)

Seals a value.

SealText(ReadOnlySpan<byte>, string, string)

Seals text into a form that can be written where only text fits.