MRAM Random Number Generator via Magnetic Relaxation
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Solution Overview
Problem
Current pseudo random number generators in wireless communications lack true randomness and are susceptible to external attacks, posing security risks in applications like secure bank cards and SIM cards.
Innovation Solution
A MRAM-based programmable magnetic device utilizing an array of magnetic tunnel junctions, where the storage magnetization is oriented in an unstable configuration and relaxed randomly to one of several stable or metastable configurations through heating and cooling, generating a true random number.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pseudo random number generators based on CMOS ring oscillators are used, then device complexity is reduced and ease of manufacture is improved, but true randomness is lost and security reliability deteriorates
Solution Approach 1:
The patent replaces the electronic CMOS ring oscillator system with a magnetic physical system based on magnetic tunnel junctions. The random number generation is achieved through physical magnetic domain switching and thermal fluctuation mechanisms rather than electronic oscillation, providing true randomness while maintaining manufacturability through standard MRAM fabrication processes
Solution Approach 2:
The patent utilizes temperature as a control parameter to induce random magnetic switching. By heating the magnetic tunnel junction above the blocking temperature and then cooling it, the system exploits thermal fluctuations to create unpredictable magnetization states, generating true random numbers through physical parameter changes rather than deterministic electronic processes
2Reliability
If magnetic tunnel junctions are heated to high temperature to orient storage magnetization in unstable configuration, then random number generation capability is improved, but energy consumption increases
Solution Approach 1:
The patent employs periodic heating and cooling cycles to the magnetic tunnel junction to generate random numbers. The system heats the junction above the blocking temperature to create an unstable magnetic state, then allows controlled cooling to let the magnetization relax into a random stable configuration. This periodic thermal cycling enables continuous random number generation with manageable energy consumption by resetting the system in discrete cycles
Solution Approach 2:
The patent exploits the phase transition of the storage layer magnetization at the blocking temperature. By heating above this critical temperature point, the magnetic anisotropy is suppressed and the magnetization becomes unstable. During subsequent cooling, the magnetization randomly selects one of multiple stable configurations, generating entropy through this thermal phase transition process
3Reliability
If the storage magnetization is orientable in unstable magnetization configuration, then true random number generation is achieved, but device stability deteriorates
Solution Approach 1:
The patent creates a dynamically controllable magnetic system where the stability of the storage layer magnetization can be switched between stable and unstable states. By applying thermal energy (heating above blocking temperature) or magnetic field, the system transitions from a stable magnetized state to an unstable demagnetized state suitable for random number generation. After generating the random state, the system can be returned to stability through controlled cooling or field application, enabling repeated use
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a secure, energy-efficient, and compact method for generating random numbers, allowing for nonvolatile data retention and integration into various devices, enhancing security in wireless communications.
Implementation Method 1
heating the magnetic tunnel junction to a predetermined high temperature such as to orient the storage magnetization in the unstable magnetization configuration
Implementation Method 2
cooling the magnetic tunnel junction to a predetermined low temperature such as to let the storage magnetization relax randomly in one of said plurality of stable or metastable configurations
Implementation Method 3
The insulating layer is so thin that electrons can tunnel through the barrier if a bias voltage is applied between the two metal electrodes. In magnetic tunnel junctions the tunneling current, and thus the resistance of the magnetic tunnel junction, depends on the relative orientation of magnetizations of the two ferromagnetic layers
Data Source
AI summary
A programmable magnetic device for generating random numbers during a programming operation, including an array of a plurality of magnetic tunnel junctions. Each magnetic tunnel junction includes a reference layer having a reference magnetization; a tunnel barrier layer; and a storage layer having a storage magnetization. The programmable magnetic device is arranged such that, during the programming operation, the storage magnetization is orientable in an unstable magnetization configuration and relaxable randomly in one of a plurality of stable or metastable configurations from the unstable magnetization configuration.