review https://github.com/Coldcard/firmware/blob/2021-01-14T1617-v3.2.2/stm32/COLDCARD/vcp_lockdown.c
vs.
https://github.com/Coldcard/firmware/commit/dac940cc893ace370738c0c4ce3f763036089a8f#diff-b14a0bb021c4ebd7f34d21aae7f7374e894c99008d99a225f14da4cf2fdc7c7e
In pre-4.0.0 firmware, the ckcc_vcp_enabled is set to false.
The 4.0.1 patch on top of 4.0.0 is:
- //XXX/bool ckcc_vcp_enabled = false;
- bool ckcc_vcp_enabled = true;
+ extern bool ckcc_vcp_enabled;
So pre 4.0.0, USB issue does not exist because this value was set to false. In 4.0.1, this is changed from "true" to "false", closing the issue that only appeared in the update from pre-4.
Does that make sense? there is a bug that didn't exist pre-4.0.0 that was introduced in the refactor, that isn't the entropy bug. Matt's guides were for air gap usage, so you would no be impacted by this bug if you followed the guide.
average_gary
npub160…zyjc9
2026-08-05 18:58:19 UTC
in reply to nevent1q…zrll
Author Public Key
npub160t5zfxalddaccdc7xx30sentwa5lrr3rq4rtm38x99ynf8t0vwsvzyjc9Seen on
wss://premium.primal.netPublished at
2026-08-05 18:58:19 UTCEvent JSON
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"content": "review https://github.com/Coldcard/firmware/blob/2021-01-14T1617-v3.2.2/stm32/COLDCARD/vcp_lockdown.c\nvs.\nhttps://github.com/Coldcard/firmware/commit/dac940cc893ace370738c0c4ce3f763036089a8f#diff-b14a0bb021c4ebd7f34d21aae7f7374e894c99008d99a225f14da4cf2fdc7c7e\n\nIn pre-4.0.0 firmware, the ckcc_vcp_enabled is set to false.\nThe 4.0.1 patch on top of 4.0.0 is:\n- //XXX/bool ckcc_vcp_enabled = false;\n- bool ckcc_vcp_enabled = true;\n+ extern bool ckcc_vcp_enabled;\n\nSo pre 4.0.0, USB issue does not exist because this value was set to false. In 4.0.1, this is changed from \"true\" to \"false\", closing the issue that only appeared in the update from pre-4.\n\nDoes that make sense? there is a bug that didn't exist pre-4.0.0 that was introduced in the refactor, that isn't the entropy bug. Matt's guides were for air gap usage, so you would no be impacted by this bug if you followed the guide.",
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