When you can configure key masking for datetime values, the Data Masking transformation requires a random number as a seed. You can change the seed to match the seed value for another column in order to return repeatable datetime values between the columns.
The Data Masking transformation can mask dates between 1753 and 2400 with key masking. If the source year is in a leap year, the Data Masking transformation returns a year that is also a leap year. If the source month contains 31 days, the Data Masking transformation returns a month that has 31 days. If the source month is February, the Data Masking transformation returns February.
The Data Masking transformation always generates valid dates.