Cal. GOV § 5302

(a) Wherever any statute requires that any bond issued by a public body be signed, manually by two or more officers or other individuals, all signatures and countersignatures may be printed, lithographed, engraved, or otherwise mechanically reproduced except that one of said signatures or countersignatures to the bonds shall be manually affixed. The signature may be affixed in accordance with the provisions of the Uniform Facsimile Signatures of Public Officials Act, Chapter 6 (commencing with Section 5500) of Title 1.

(b) Notwithstanding subdivision (a), the governing board of the public body may, in its discretion, determine that all of the required signatures and countersignatures shall be by facsimiles, provided, however, that the bonds shall not be valid or become obligatory for any purpose until manually signed by an authenticating agent duly appointed by the governing board or its authorized designee.