Innovative Encryption Solutions to Help Prevent Side Channel Attacks

Encryption is an essential element of effective cybersecurity and data protection. Only systems or individuals with the correct encryption keys are able to decipher and view the encrypted data. Of course, attackers know that too—which is why they work diligently to find ways to steal secret encryption keys and digital identities. Side channel attacks (SCA) are a creative way for hackers to try and capture keys and break encryption, but two potential new solutions from Intel are designed to raise the bar and show promise to help prevent these attacks from succeeding.

Secure public key encryption is essential for maintaining the integrity of key exchange and digital signatures and maintaining the efficacy and viability of encryption. The length and complexity of the keys offer protection against most brute force or other cracking attempts, but increasingly attackers are working to leverage side channel attacks to undermine encryption. Secure public key encryption is part of the foundation of online security, so it is crucial to take steps to protect it. Intel’s researchers recognize the importance of collaborating within the cybersecurity community to continuously investigate new ways to address these attacks and help protect users from potential vulnerabilities.

Side Channel Attacks

If an attacker can get the keys used for encryption, they can gain access to the system or data. Getting the keys directly would be great, but most organizations are vigilant about safeguarding encryption keys. Cyber criminals work diligently to come up with innovative solutions when they need to, though, and for that reason may look to side channel attacks as an alternative strategy to attempt to access secret information.

The challenge is that side channels are intrinsic to any system, and do not represent flaws or vulnerabilities—a “side channel” is simply a strategy to observe and infer information from normal operations. Thus, a physical side channel attack essentially attempts to outflank security measures by using information gained regarding the implementation of an encryption system, rather than trying to directly attack the encryption algorithm itself. Observable factors of the encryption system may provide useful insight that can help enable an attacker to compromise the encryption. Information that seems innocuous like timing information, power consumption, electromagnetic activity, and sound reveal clues that can be exploited to crack the encryption.

More Resilient Encryption

As attackers come up with more clever ways to gather information to break encryption, vendors need to develop innovative ways to make it more challenging and make the encryption more resilient to those attacks. As a part of its effort to promote transparency and information sharing within the security community, Intel recently published two papers about encryption and resilience against electromagnetic-emission side-channel attacks / verifying digital signatures (attestation). One paper describes a side channel attack resistant crypto processor for secure RSA encryption, and the other describes a side channel attack resistant AES engine. Both solutions are designed to further raise the bar for protecting the security and integrity of encryption.

SCA Resistant Crypto Processor for Secure RSA Encryption

Conventional RSA encryption implementations may be vulnerable to power and electromagnetic (EM) side channel attacks, and traditional countermeasures may not be fully effective. Intel’s paper presents a SCA resistant approach that uses exponent timing randomization, exponent magnitude randomization, register file address space randomization. The result is lower means-separation in current/EM trace magnitudes, which is intended to reduce the accuracy of a side-channel attack to essentially a random guess.

SCA Resistant AES Engine

AES is one of the most popular encryption algorithms in use today. It is commonly used to encrypt data on hard drives, as well as applications and across the internet. It is imperative that the AES encryption key is not leaked. The more data an attacker can gather, the more powerful an attack will be and the greater the chances of breaking the encryption and compromising the system or data.

Power / EM side channel attacks seek to exploit data-dependent current or electromagnetic signatures from cryptographic engines to extract secret keys. There are preventive measures that work on a limited basis, but they are less effective against frequency-domain attacks. Using a combination of a randomized non-linear digital low-dropout regulator (ND-DLDO) with arithmetic countermeasures improves protection exponentially. Analysis of this AES engine revealed that it increases the minimum time to disclosure (MTD) by more than 250,000 times in both time and frequency-domains.

These engines scramble the electromagnetic power consumption of engines so that whatever leakages exist in current consumptions are now taken care of. For more technical details on these implementations and how they work to protect against side channel attacks, take a look at the papers from Intel.

As hardware and software security improves in general, attackers will continue to find creative ways to subvert or circumvent security controls. Side channel attacks that take advantage of the normal operation of a system are insidious because the system is working the way it should. The initiatives being developed by Intel demonstrate Intel’s continuous commitment to its security-first pledge—learning from and sharing with the security community – and could have a major impact in helping to protect users from these types of attacks.