The disclosure relates to storing a blockchain private key on a SIM device and securing the blockchain private key through multi-factor authentication. Various layers of security that controls access to the blockchain private key on the SIM device may be employed. These layers may include authentication of the user device on the cellular network using the SIM device, storage on a hidden partition of the SIM device that only a key applet executing on the SIM device or on a user device processor is aware of, storage of the blockchain private key in encrypted form, and/or use of the key applet to enforce credentialed access to the blockchain private key (e.g., the key applet obtains from the hidden partition and/or decrypts the blockchain private key only if a valid passcode is supplied to it).