Md. Code, Election Law § 13–234

(a) A contribution of money may be made only by:

(1) check;

(2) credit card;

(3) cash, if the contribution does not exceed $100 in an election cycle; or

(4) an electronic method that the State Board authorizes by regulation.

(b) An electronic method of making a contribution that the State Board authorizes under this section shall ensure that:

(1) the identity of the person making the contribution may be verified;

(2) the transaction is secure; and

(3) there is an adequate record of the transaction.