The San Francisco Municipal Transportation Authority, or SF MTA, was hacked on Friday. “You Hacked, All Data Encrypted,” was the message reportedly displayed on computer screens at the authority’s stations throughout the city. “Contact for Key (cryptom27@yandex.com)ID:681 , Enter.” Fare payment machines at underground stations were out of order, resulting in free rides on the subway and light rail system known locally as “SF Muni.” Some SF MTA employees’ email systems reportedly did not work.