Which masking technique produces deterministic results for the same source and seed value?

Key masking is a technique that utilizes a specific key or seed value to ensure that the same input data consistently produces the same masked output. This deterministic nature allows for predictable results, which can be crucial for certain applications where data consistency is necessary, such as in testing or data analysis scenarios.

In key masking, the algorithm applies a cryptographic key or seed to the masking process, meaning that each distinct combination of source data and seed generates a specific, reproducible output. This predictability is beneficial when you need to ensure that the masked data can be matched back to the original format under secure conditions, allowing for testing while protecting sensitive information.

For other techniques such as random masking, the results can differ across executions due to the use of randomness, thus not ensuring the same output for identical inputs. Substitution masking can involve variable replacements and wouldn't necessarily provide the same output values consistently without a deterministic approach. Consequently, the predictability and reproducibility of key masking make it the right choice for this question.