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factor out key routine, fail early on MFM disks for now

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4am 2022-09-29 18:58:27 -04:00
parent 74e8e994c9
commit cfadf05a96
1 changed files with 26 additions and 20 deletions
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46
moofimage.py
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@ -206,9 +206,31 @@ class MoofRWTS:
def verify_data_epilogue_at_point(self, track):
return self.verify_nibbles_at_point(track, self.data_epilogue)
def get_pace_key_at_point(rwts, track, bit_index):
track.bit_index, bit_index = bit_index, track.bit_index
key = []
prologue = (0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xAB, 0xCD, 0xEF, 0xEF)
if rwts.verify_nibbles_at_point(track, prologue):
for i in range(4):
next(track.nibble())
for i in range(4):
x = (next(track.nibble()) << 8) + next(track.nibble())
x = x & 0x5555
x = (x | (x >> 1)) & 0x3333
x = (x | (x >> 2)) & 0x0f0f
x = (x | (x >> 4)) & 0x00ff
x = (x | (x >> 8)) & 0xffff
key.append(x)
key.reverse()
track.bit_index, bit_index = bit_index, track.bit_index
return "".join(map(myhex, key))
def driver(filename):
with open(filename, 'rb') as f:
mdisk = MoofDiskImage(f)
if not mdisk.info["disk_type"] in (1,2):
print("/!\ MFM disks not supported yet")
return
rwts = MoofRWTS()
for track_index in mdisk.tmap:
if track_index == 0xFF: continue
@ -231,27 +253,11 @@ def driver(filename):
continue
if address_field.sector_id in seen_sectors: break
seen_sectors.append(address_field.sector_id)
bit_index = track.bit_index
old_bit_index = track.bit_index
if not rwts.find_data_prologue(track):
track.bit_index = bit_index
if rwts.verify_nibbles_at_point(track, (0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xAB, 0xCD, 0xEF, 0xEF)):
print(f'/!\ track {myhex(address_field.track_id)}, sector {myhex(address_field.sector_id)}: found PACE decryption key ', end='')
# extract PACE decryption key
for i in range(4):
next(track.nibble())
key = []
for i in range(4):
x = (next(track.nibble()) << 8) + next(track.nibble())
x = x & 0x5555
x = (x | (x >> 1)) & 0x3333
x = (x | (x >> 2)) & 0x0f0f
x = (x | (x >> 4)) & 0x00ff
x = (x | (x >> 8)) & 0xffff
key.append(x)
key.reverse()
for x in key:
print(myhex(x), end='')
print()
key = get_pace_key_at_point(rwts, track, old_bit_index)
if key:
print(f'/!\ track {myhex(address_field.track_id)}, sector {myhex(address_field.sector_id)}: found PACE decryption key {key}')
continue
try:
valid, sector_id, tags, decoded_bytes = rwts.data_field_at_point(track)