Government Code § 16.5.
(a) In any written communication with a public entity, as defined in Section 811.2, in which a signature is required or used, any party to the communication may affix a signature by use of a digital signature that complies with the requirements of this section. The use of a digital signature shall have the same force and effect as the use of a manual signature if and only if it embodies all of the following attributes:
(1) It is unique to the person using it.
(2) It is capable of verification.
(3) It is under the sole control of the person using it.
(4) It is linked to data in such a manner that if the data are changed, the digital signature is invalidated.
(5) It conforms to regulations adopted by the Secretary of State. Initial regulations shall be adopted no later than January 1, 1997. In developing these regulations, the secretary shall seek the advice of public and private entities, including, but not limited to, the Department of Information Technology, the California Environmental Protection Agency, and the Department of General Services. Before the secretary adopts the regulations, he or she shall hold at least one public hearing to receive comments.
(b) The use or acceptance of a digital signature shall be at the option of the parties. Nothing in this section shall require a public entity to use or permit the use of a digital signature.
(c) Digital signatures employed pursuant to Section 71066 of the Public Resources Code are exempted from this section.
(d) "Digital signature" means an electronic identifier, created by computer, intended by the party using it to have the same force and effect as the use of a manual signature.