According to the report, 2.5 million Californians' personal information was put at risk through data breaches in 2012. The average breach involved 22,500 individuals' personal information, and five breaches affected 100,000 people or more.
The retail industry reported the most data breaches (26 percent), followed by finance and insurance (23 percent), and health care (15 percent).
Fully 56 percent of the breaches involved Social Security numbers.
Still, the report says 28 percent of the data breaches would not have required notification, and more than 1.4 million Californians' personal information would not have been put at risk, if the affected data had been encrypted.
"Data breaches are a serious threat to individuals' privacy, finances and even personal security," Harris said in a statement. "Companies and government agencies must do more to protect people by protecting data."