Envelope AEAD Malleability
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- Affected Versions
- All Tink versions
- Affected Key Types
- All Envelope AEAD key types
Description
Envelope encryption uses a third-party provider
(such as GCP or AWS) to encrypt a data encryption key (DEK).
It is possible to modify certain parts of the encrypted DEK without detection
when using KmsEnvelopeAead with AwsKmsAead or GcpKmsAead as the remote
provider. This is due to the inclusion of unauthenticated metadata (for instance
version numbers). Modifications to this unauthenticated data are not detected by
the provider.
Note that this violates the adaptive chosen-ciphertext attack property
(IND-CCA-2) for this interface, although the ciphertext can still decrypt to
the correct DEK. When using this interface don't presume that each DEK only
corresponds to a single encrypted DEK.
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Last updated 2024-11-14 UTC.
[null,null,["Last updated 2024-11-14 UTC."],[[["\u003cp\u003eAll versions of Tink and all Envelope AEAD key types are affected by a security vulnerability.\u003c/p\u003e\n"],["\u003cp\u003eThe vulnerability allows modification of unauthenticated metadata within encrypted data encryption keys when using KmsEnvelopeAead with AwsKmsAead or GcpKmsAead.\u003c/p\u003e\n"],["\u003cp\u003eWhile the ciphertext can still be decrypted, this vulnerability violates the adaptive chosen-ciphertext attack property (IND-CCA-2).\u003c/p\u003e\n"],["\u003cp\u003eDevelopers should be aware that a single data encryption key might correspond to multiple encrypted data encryption keys due to this issue.\u003c/p\u003e\n"]]],["Envelope encryption, using `KmsEnvelopeAead` with `AwsKmsAead` or `GcpKmsAead`, allows undetectable modifications to the encrypted data encryption key (DEK) due to unauthenticated metadata. All Tink versions and Envelope AEAD key types are affected. While decryption still yields the correct DEK, this violates the adaptive chosen-ciphertext attack property (IND-CCA-2). Each DEK may correspond to multiple encrypted DEKs; users shouldn't assume a one-to-one mapping.\n"],null,["# Envelope AEAD Malleability\n\nAffected Versions\n: All Tink versions\n\nAffected Key Types\n: All Envelope AEAD key types\n\nDescription\n-----------\n\n[Envelope encryption](/tink/client-side-encryption) uses a third-party provider\n(such as GCP or AWS) to encrypt a data encryption key (DEK).\n\nIt is possible to modify certain parts of the encrypted DEK without detection\nwhen using `KmsEnvelopeAead` with `AwsKmsAead` or `GcpKmsAead` as the remote\nprovider. This is due to the inclusion of unauthenticated metadata (for instance\nversion numbers). Modifications to this unauthenticated data are not detected by\nthe provider.\n\nNote that this violates the adaptive chosen-ciphertext attack property\n(IND-CCA-2) for this interface, although the ciphertext can still decrypt to\nthe correct DEK. When using this interface don't presume that each DEK only\ncorresponds to a single *encrypted DEK*."]]
