fix(gcpkms): verify ciphertext_crc32c and AAD_crc32c on Decrypt response#5
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The two GcpKmsAead variants in this file (REST GcpKmsAead lines 106-135 and gRPC GcpKmsAeadGrpc lines 234-262) both set request-side CRC32C checksums on Decrypt but neither checks the response's verified_ciphertext_crc32c or verified_additional_authenticated_data_crc32c flags. The Encrypt paths in both variants already do these checks. Per Cloud KMS Data Integrity Guidelines (https://cloud.google.com/kms/docs/data-integrity-guidelines), the response must be rejected if the server did not confirm receipt of the request CRCs. This change adds the symmetric verified_*_crc32c response checks to both Decrypt variants, matching the existing Encrypt-side pattern in the same file. Sibling fixes: tink-go-gcpkms#21, tink-cc-gcpkms#2, tink-cc-gcpkms#3, tink-py PR #77 (Python had no CRC32C at all on either direction).
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Background
The two GcpKmsAead variants in
GcpKmsAead.java(RESTGcpKmsAeadat lines 106-135 and gRPCGcpKmsAeadGrpcat lines 234-262) both set request-side CRC32C checksums ondecrypt, but neither checks the response'sverified_ciphertext_crc32corverified_additional_authenticated_data_crc32cflags. TheEncryptpaths in both variants already perform these checks.Per the Cloud KMS Data Integrity Guidelines, the response must be rejected if the server did not confirm receipt of the request CRCs.
Change
Decryptnow fails closed on:!response.getVerifiedCiphertextCrc32c()!response.getVerifiedAdditionalAuthenticatedDataCrc32c()in both the REST variant (using boxed
Booleangetters with null-check) and the gRPC variant (using primitivebooleangetters), matching the existing Encrypt-side patterns in the same file.Sibling fixes
All five PRs converge on the same Cloud KMS Data Integrity Guidelines compliance.