com.google.crypto.tink.aead

Class LegacyKmsEnvelopeAeadParameters

java.lang.Object

com.google.crypto.tink.Parameters

com.google.crypto.tink.aead.AeadParameters

com.google.crypto.tink.aead.LegacyKmsEnvelopeAeadParameters

public final class LegacyKmsEnvelopeAeadParameters
extends AeadParameters

Describes the parameters of an LegacyKmsEnvelopeAeadKey.

Usage of this key type is not recommended. Instead, we recommend to implement the idea of this class manually:

1. Create an remote Aead object for your KMS with an appropriate Tink extension (typically using a subclass of KmsClient).
2. Create an envelope AEAD with KmsEnvelopeAead.create(com.google.crypto.tink.aead.AeadParameters, com.google.crypto.tink.Aead).

Known Issues

Global registration

If a user uses a LegacyKmsEnvelopeAeadKey, when the corresponding Aead is created, Tink looks up the KmsClient in a global registry. This registry needs to store all the credentials and all the information. This is inappropriate in many situations.

Ciphertext format

The ciphertext format does not encode the key type of the key used. This can lead to unexpected results if a user changes the dekParametersForNewKeys or the dekParsingStrategy for the same remote key. In more details, the ciphertext contains a Tink key proto of newly generated key, but not the type URL. This means that if a user reuses the same remote Key with a different key type, it will be parsed with the wrong one.

Also, Tink does note compare the parameters of the parsed key with the parameters specified in dekParametersForNewKeys. For example, if the dekParametersForNewKeys is specified as AES_128_GCM in one binary, and AES_256_GCM in another binary, communication between the binaries succeeds in both directions.

Ciphertext malleability

Some KMS have malleable ciphertexts. This means that the Aeads corresponding to these keys may be malleable. See https://developers.google.com/tink/issues/envelope-aead-malleability

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LegacyKmsEnvelopeAeadParameters.Builder Builder for LegacyKmsEnvelopeAeadParameters.
static class	LegacyKmsEnvelopeAeadParameters.DekParsingStrategy Specifies how the DEK in received ciphertexts are parsed.
static class	LegacyKmsEnvelopeAeadParameters.Variant Describes how the prefix is computed.

Method Summary

Modifier and Type	Method and Description
static LegacyKmsEnvelopeAeadParameters.Builder	builder()
boolean	equals(Object o)
AeadParameters	getDekParametersForNewKeys() Parameters used when creating new keys.
LegacyKmsEnvelopeAeadParameters.DekParsingStrategy	getDekParsingStrategy() Returns the type URL which is used when parsing encrypted keys.
String	getKekUri() Returns the URI with the key of the remote AEAD used.
LegacyKmsEnvelopeAeadParameters.Variant	getVariant()
int	hashCode()
boolean	hasIdRequirement() Returns true if a key created with the parameters in this object has to have a certain ID when it is in a keyset.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Method Detail

builder

public static LegacyKmsEnvelopeAeadParameters.Builder builder()

getKekUri

public String getKekUri()

Returns the URI with the key of the remote AEAD used.

getVariant

public LegacyKmsEnvelopeAeadParameters.Variant getVariant()

hasIdRequirement

public boolean hasIdRequirement()

Description copied from class: Parameters

Returns true if a key created with the parameters in this object has to have a certain ID when it is in a keyset.

In Tink, certain keys change their behavior depending on the key id (for example, an Aead object can prefix the ciphertext with the big endian encoding of the key id). If this is the case, such a key should require a unique id in Key.getIdRequirementOrNull() and return true here.

Specified by:

hasIdRequirement in class Parameters

getDekParsingStrategy

public LegacyKmsEnvelopeAeadParameters.DekParsingStrategy getDekParsingStrategy()

Returns the type URL which is used when parsing encrypted keys.

See "Known Issues" section above.

getDekParametersForNewKeys

public AeadParameters getDekParametersForNewKeys()

Parameters used when creating new keys.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object