Crypto-agility ('cryptographic agility') allows an information security system to switch to alternative cryptographic primitives and algorithms without making significant changes to the system's infrastructure. Crypto-agility facilitates system upgrades and evolution.
Crypto-agility can act as a safety measure or an incident response mechanism when the encryption algorithms of a system are discovered to be vulnerable. A security system is considered crypto agile if its encryption algorithms can be replaced with ease and is at least partly automated.
The retirement of the X.509 public key certificate illustrates crypto-agility. A public key certificate has cryptographic parameters including key type, key length, and a hash algorithm. X.509 version v.3, with key type RSA, a 1024-bit key length, and the SHA-1 hash algorithm were found by NIST to have a key length that made it vulnerable to attacks, thus prompting the transition to SHA-2.
Cryptographic techniques are widely incorporated to protect applications and business transactions. Since the 2010s, public key infrastructure (PKI) has been progressively integrated into business applications via public key certificates, which were used as trust foundations between network entities. PKI has better security features than traditional access control mechanisms, which incorporate cryptographic technologies such as digital certificates and signatures. Public key certificates acting as digital credentials are the core component for strong authentication and secure communication between entities through public networks. With a continuing increase in users and threats, crypto-agility has emerged as key for business security 58% of cyber attacks target small business because of their security system vulnerabilities.
Quantum computing is expected to be able to defeat existing public key cryptography algorithms. The overwhelming majority of the existing public key infrastructure rely on the computational hardness of problems such as large integer factorization and discrete logarithm problems (which includes elliptic-curve cryptography as a special case). Quantum computers running Shor's algorithm can solve these problems exponentially faster than the best known algorithms for conventional computers. Post-quantum cryptography is the subfield of cryptography that aims to replace algorithms broken with new ones that are believed hard to break even for a quantum computer. The main families of post-quantum alternatives to factoring and discrete logarithm include lattice-based cryptography, multivariate cryptography, hash-based cryptography and code-based cryptography.
System evolution and crypto-agility are not the same. System evolution progresses on the basis of emerging business and technical requirements. Crypto-agility is related instead to computing infrastructure and requires consideration by security experts, system designers and application developers.
Best practices about dealing with crypto-agility include:
- All business applications involving any sort of crypto technology should incorporate the latest algorithms and techniques.
- Crypto-agility requirements must be disseminated to all hardware, software and service suppliers, who must comply on a timely basis.
- Suppliers who cannot address these requirements must be replaced.
- Suppliers must provide timely updates and identify the crypto technology they employ.
- RSA should be replaced by quantum-resistant solutions.
- Symmetric-key algorithm have to be used with long key lengths.
- Hash algorithms must use high bit sizes.
- Comply with standards and regulations.
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