How to use the command 'gcloud kms decrypt' (with examples)
This article will guide you through the various use cases of the command ‘gcloud kms decrypt’, which is used to decrypt a ciphertext file using a Cloud KMS key. The ‘gcloud kms decrypt’ command is a part of the Google Cloud SDK and can be used to securely decrypt data stored in Google Cloud Storage or any other storage system. It provides a reliable and easy-to-use method for decrypting data with the help of Cloud KMS keys.
Use case 1: Decrypt a file using a specified key, key ring, and location
Code:
gcloud kms decrypt --key=key_name --keyring=keyring_name --location=global --ciphertext-file=path/to/ciphertext --plaintext-file=path/to/plaintext
Motivation: This use case is suitable when you have a ciphertext file that you want to decrypt with a specific Cloud KMS key, key ring, and location. It is essential for security reasons to ensure that only authorized users can access the decrypted plaintext.
Explanation:
--key=key_name: Specifies the name of the Cloud KMS key to be used for decryption.--keyring=keyring_name: Specifies the name of the key ring where the specified key is stored.--location=global: Specifies the location of the key ring and key.--ciphertext-file=path/to/ciphertext: Specifies the path to the ciphertext file that needs to be decrypted.--plaintext-file=path/to/plaintext: Specifies the path where the decrypted plaintext will be stored.
Example output: An output file named “plaintext” will be created at the specified location, containing the decrypted plaintext data from the ciphertext file.
Use case 2: Decrypt a file with additional authenticated data (AAD) and write the decrypted plaintext to stdout
Code:
gcloud kms decrypt --key=key_name --keyring=keyring_name --location=global --additional-authenticated-data-file=path/to/file.aad --ciphertext-file=path/to/ciphertext --plaintext-file=-
Motivation: This use case is valuable when you want to decrypt a file with the help of a Cloud KMS key, key ring, and location while using additional authenticated data (AAD). With AAD, you can ensure the integrity and authenticity of the ciphertext and provide an extra level of security.
Explanation:
--key=key_name: Specifies the name of the Cloud KMS key to be used for decryption.--keyring=keyring_name: Specifies the name of the key ring where the specified key is stored.--location=global: Specifies the location of the key ring and key.--additional-authenticated-data-file=path/to/file.aad: Specifies the path to the additional authenticated data file (AAD).--ciphertext-file=path/to/ciphertext: Specifies the path to the ciphertext file that needs to be decrypted.--plaintext-file=-: Writes the decrypted plaintext to stdout.
Example output: The decrypted plaintext will be printed to the terminal rather than saving it to a file.
Conclusion:
As demonstrated in this article, the ‘gcloud kms decrypt’ command provides various use cases for decrypting ciphertext files using Cloud KMS keys. It offers flexibility, security, and ease of use for decrypting sensitive data in a reliable manner. By following the examples provided, you can confidently use this command to decrypt your data stored in Google Cloud Storage or other storage systems.
