Alicia Keys already has a lot of mystique to live up to for such a tender thing. On her debut, Songs in A Minor, she was acclaimed as a soul prodigy fusing Biggie and Chopin. Keys played piano, wrote the great “Fallin’,” wore a cool hat and won more Grammys than she’d had hot breakfasts. But success hasn’t spoiled her, because she’s clearly been woodshedding. The Diary of Alicia Keys is an assured, adult statement, steeped in the complicated love life and musical dreams of an ambitious young woman who has absorbed enough Nina Simone and Aretha Franklin records to live up to the soul promise of “Harlem’s Nocturne.” Keys evokes Gladys Knight (“If I Was Your Woman”) and Dionne Warwick (“Walk On By”), but the seductive adult spell of “You Don’t Know My Name” is all her own.