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  1. BUILD.bazel

Java Google Cloud Storage (GCS) client-side encryption example

This example shows how to encrypt/decrypt GCS blobs with Tink using Envelope Encryption.

It shows how you can use Tink to encrypt data with a newly generated data encryption key (DEK) which is wrapped with a KMS key. The data will be encrypted with AES256 GCM using the DEK and the DEK will be encrypted with the KMS key and stored alongside the ciphertext in GCS.

The CLI takes the following required arguments:

  • mode: “encrypt” or “decrypt” to indicate if you want to encrypt or decrypt.
  • kek-uri: The URI for the Cloud KMS key to be used for envelope encryption.
  • gcp-credential-file: Name of the file with the Google Cloud Platform (GCP) credentials (in JSON format) that can access the Cloud KMS key and the GCS input/output blobs.
  • gcp-project-id: The ID of the GCP project hosting the GCS blobs that you want to encrypt or decrypt.

When mode is “encrypt”, it takes the following additional arguments:

  • local-input-file: Read the plaintext from this local file.
  • gcs-output-blob: Write the encryption result to this blob in GCS. The encryption result is bound to the location of this blob. That is, if you rename or move it to a different bucket, decryption will fail.

When mode is “decrypt”, it takes the following additional arguments:

  • gcs-input-blob: Read the ciphertext from this blob in GCS.
  • local-output-file: Write the decryption result to this local file.

gcs-input-blob and gcs-output-blob have this format: gs://my-bucket-name/my-object-name.

Build and Run


This envelope encryption example uses a Cloud KMS key as a key-encryption key (KEK). In order to run it, you need to:

  • Create a symmetric key on Cloud KMS. Copy the key URI which is in this format: projects/<my-project>/locations/global/keyRings/<my-key-ring>/cryptoKeys/<my-key>.

  • Create a bucket on GCS.

  • Create and download a service account that is allowed to encrypt and decrypt with the Cloud KMS key, and read/write to the GCS bucket.


git clone
cd tink/examples/java_src
bazel build ...

Encrypt a file and upload it to GCS:

echo "some data" > testdata.txt

./bazel-bin/gcs/gcs_envelope_aead_example \
    encrypt \
    gcp-kms://my-cloud-kms-key-uri \
    my-service-account.json \
    my-gcp-project-id \
    testdata.txt gs://my-bucket-name/my-blob-name

Download a file from GCS and decrypt it:

./bazel-bin/gcs/gcs_envelope_aead_example \
    decrypt \
    gcp-kms://my-key-uri \
    my-service-account.json \
    my-gcp-project-id \
    gs://my-bucket-name/my-blob-name testdata.txt.decrypted