Pseudonymization method that generates surrogates via cryptographic
hashing. Uses SHA-256. The key size must be either 32 or 64 bytes.
Outputs a base64 encoded representation of the hashed output (for
example, L7k0BHmF1ha5U3NfGykjro4xWi1MPVQPjhMAZbSV9mM=). Currently,
only string and integer values can be hashed. See
https://cloud.google.com/dlp/docs/pseudonymization to learn more.
.. attribute:: crypto_key