ASR

Apple System Restore (also known as ASR) is an application found on the Ramdisks of an IPSW firmware file. It works by writing the rootfs image to the actual system drive (ASR RESTORE), then checksums it. (ASR VERIFY)

ASR Verify Disassembly
__text:00014204 loc_14204                              ; CODE XREF: sub_13AB4+61E�j __text:00014204                                        ; sub_13AB4+73E�j __text:00014204                LDR     R3, =(off_235E8 - 0x1420A) __text:00014206                ADD     R3, PC __text:00014208                 LDR     R3, [R3] __text:0001420A                LDR     R3, [R3] __text:0001420C                CMP     R3, #0 __text:0001420E                BEQ     loc_1427A __text:00014210                LDR     R0, =(aImagePassedSig - 0x14216) __text:00014212                ADD     R0, PC          ; "Image passed signature verification" __text:00014214                BLX     _warnx __text:00014218                B       loc_1427A __text:0001421A ; --- __text:0001421A __text:0001421A loc_1421A                              ; CODE XREF: sub_13AB4+622�j __text:0001421A                                        ; sub_13AB4+628�j ... __text:0001421A                LDR.W   R0, =(aImageFailedSig - 0x14222) __text:0001421E                ADD     R0, PC          ; "Image failed signature verification" __text:00014220                BLX     _warnx __text:00014224                MOVS    R2, #0x50 __text:00014226                B       loc_1426E __text:00014228 ; ---