san francisco facebook inc fb.o twitter inc twtr.n two silicon valley powerful company thursday back apple inc aapl.o refusal help fbi break iphone use shooter san bernardino attack say comply would set dangerous precedent privacy take two days company entry solidify small powerful band tech giants support apple quest buck government demand say would irreparably damage security erode consumer trust among first come apple defense chief rival chief executive officer sundar pichai alphabet inc googl.o google tweet support apple wednesday company stay mum yahoo inc yhoo.o microsoft corp msft.o yet weigh case characteristic fashion twitter ceo jack dorsey use service lend support apple ceo tim cook tweet `` stand tim_cook apple thank leadership `` bit.ly/1rbfi5j statement facebook say continue fight aggressively requirements company weaken security systems case intensify rift tech company law enforcement limit encryption law enforcement group vocal support justice department although firm remain silent industry firmly apple side say aaron levie ceo cloud-based storage provider box inc box.n company choose use political capital really important relevant levie say individually press would see message essentially internet hardware enterprise software ceo company fundamental security model technology would break comply kind order levie say unequivocally support cook stance whole ground apple stand super important say center case iphone use rizwan farook along wife tashfeen malik kill 14 people wound 22 shoot rampage san bernardino california young marry couple sympathize islamic state militants government investigators want data phone learn activities day shoot contact either accomplices islamic state apple cook say court demand threaten security apple customers implications far beyond legal case hand facebook twitter support apple encryption dispute fbi