Compare with previous MK3 version here
- Connector: USB-C
- # of Secure Elements: 2
- CPU Speed: 120 MHz
- Memory: 840 kB + 8 MB RAM
- Flash Memory (Firmware): ≈ 1.5 MB
- Settings Memory: 512 kB
- Additional Secure Storage: 216 (3 x 72) bytes
- USB-In-Use LED ✅
- Debug Serial Port: Physical (Pins)
- Sliding Cover ✅
- NFC-V Compatible ✅
- PSBT Location: PSRAM
- Trick PINs: ✅
- USB Virtual Disk Mode: ✅
- Firmware Upgrade Time: 15 seconds
- Bitcoin Transaction Size Limit: 2 MB
NFC is the technology behind tap-to-pay and keyless entry. You’ll soon be able to sign a transaction with a tap of your COLDCARD, but only if you choose to.
The NFC feature is turned off by default and can be rendered unusable — permanently — by cutting a trace on the board. No other functions use the destructible trace.
Those who opt to enable NFC can use it for all PSBT, transaction, address sharing, and similar data.
USB Virtual Disk Mode
Another data transfer option is Virtual Disk Mode: connect the Mk4 to a computer or mobile phone and it sees the Mk4 as a 4 MB USB stick. Using your COLDCARD Mk4 with web browsers and other PSBT sources is effortless because you can save directly to your Mk4.
Increased Performance and Security
The Mk4 takes advantage of its new hardware to provide faster and more secure transactions:
- MCU implements SHA-256 and AES natively for quicker encryption/decryption.
- PSRAM provides a faster workspace than flash memory. PSBTs and other transaction data are now held in PSRAM.
- Boot ROM incorporates anti-chip shouting/glitching protections which reduce timing certainty.
- Settings are now in the MCU, rather than an external settings chip, allowing more space for settings and quicker response times.
- Second Secure Element expands the duress labyrinth to keep your secrets safe:
Highly customizable Trick PINs can be configured to temporarily or permanently disable your COLDCARD, or just wipe the stored seed, in an instant.
- Fast Wipe (immediate clearing of seed words) added to Countdown to Login feature.
- New Kill Key option – select a key to press when anti-phishing words are displayed which will trigger a Fast Wipe during login.