A computer-implemented technique processes a potentially sensitive item of data (e.g., data which may be either a credit card number or a token having a similar format). The technique involves, after the potentially sensitive item of data is properly received within a physical memory location, generating a token result which indicates whether the potentially sensitive item of data satisfies a valid-token requirement. The technique further involves preserving the potentially sensitive item of data in an unaltered form within the physical memory location when the token result indicates that the potentially sensitive item of data satisfies the valid-token requirement. The technique further involves replacing the potentially sensitive item of data within the physical memory location with a token when the token result indicates that the potentially sensitive item of data does not satisfy the valid-token requirement.