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change anti-tamper patch logic to skip calculating checksums only #26

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change anti-tamper patch logic to skip calculating checksums only #26

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1467a87
change anti-tamper patch logic to skip calculating checksums only
m-kozlowski Feb 24, 2026
93affe6
Add support for Lumis SX584-0204 in patch_tamper and bypass_startcheck
m-kozlowski Feb 25, 2026
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34 changes: 31 additions & 3 deletions patch-airsense
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Original file line number Diff line number Diff line change
Expand Up @@ -69,9 +69,37 @@ check_hash() {
cp "$IN" "$OUT" || die "$OUT: copy failed"

patch_tamper() {
# patch the jump instruction that checks for tamper
printf '\xc0\x46' | patch 0xf0 \
|| die "startup patch failed"
# All firmware versions across airsense and aircurve devices have BID=SX577-0200
# But Lumis running on SX585-0200 is unique

local version=$(dd if="$OUT" bs=1 skip=$((0x3f80)) count=10 2>/dev/null)

case "$version" in
"SX577-0200")
echo -n "Patching firmware integrity checks... "
# Skip BLX check
printf '\x01\x20\xc0\x46' | patch 0x310e && echo -n "BLX ok " || die "patch failed (BLX)"
# Skip CCX check
printf '\x00\x20\xc0\x46' | patch 0x313e && echo -n "CCX ok " || die "patch failed (CCX)"
# Skip CDX check
printf '\x00\x20\xc0\x46' | patch 0x3130 && echo -n "CDX ok " || die "patch failed (CDX)"
echo
;;
"SX585-0200")
# Skip BLX check
printf '\x01\x20\xc0\x46' | patch 0x316e && echo -n "BLX ok " || die "patch failed (BLX)"
# Skip CCX check
printf '\x00\x20\xc0\x46' | patch 0x319e && echo -n "CCX ok " || die "patch failed (CCX)"
# Skip CDX check
printf '\x00\x20\xc0\x46' | patch 0x3190 && echo -n "CDX ok " || die "patch failed (CDX)"
echo
;;
*)
die "Unknown bootloader version: '$version'"
# or try previous method if you know what you're doing
# printf '\xc0\x46' | patch 0xf0 || die "startup patch failed"
;;
esac
}

patch_strings() {
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16 changes: 13 additions & 3 deletions python/patch-airsense.py
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Original file line number Diff line number Diff line change
Expand Up @@ -260,10 +260,20 @@ def __init__(self, asf):

def bypass_startcheck(self):
#Start-up check for CRC etc, bypass it to avoid (might not be needed)
if self.asf.hash == self.known_units[0].hash:
asf.patch(b'\xc0\x46', 0xF0, clobber=True)
loader = self.asf.str_loader_ver.strip('\x00')

if loader.startswith('SX577-0200'):
# AirSense / AirCurve variant
asf.patch(b'\x01\x20\xc0\x46', 0x310e, clobber=True) # BLX
asf.patch(b'\x00\x20\xc0\x46', 0x313e, clobber=True) # CCX
asf.patch(b'\x00\x20\xc0\x46', 0x3130, clobber=True) # CDX
elif loader.startswith('SX585-0200'):
# Lumis
self.asf.patch(b'\x01\x20\xc0\x46', 0x316e, clobber=True) # BLX
self.asf.patch(b'\x00\x20\xc0\x46', 0x319e, clobber=True) # CCX
self.asf.patch(b'\x00\x20\xc0\x46', 0x3190, clobber=True) # CDX
else:
raise IOError("Unknown hash: %s"%self.asf.hash)
raise IOError("Unknown bootloader version: '%s' (hash: %s)" % (loader, self.asf.hash))

def change_text(self):
if self.asf.hash == self.known_units[0].hash:
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