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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.[1] A security system is considered crypto agile if its encryption algorithms can be replaced with ease and is at least partly automated.[2][3]


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.[4]


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.[5] Public key certificates acting as digital credentials are the core component for strong authentication and secure communication between entities through public networks.[6] 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.[7]

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[8]. 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.[9]

Best practices[edit]

Best practices about dealing with crypto-agility include:[10]

  • 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.[11]
  • Symmetric-key algorithm have to be used with long key lengths.
  • Hash algorithms must use high bit sizes.
  • Comply with standards and regulations.[12]


  1. ^ Henry, Jasmine. "What is Crypto-Agility?". Cryptomathic. Retrieved 26 November 2018.
  2. ^ Patterson, Royal Holloway, University of London, Kenny. "Key Reuse: Theory and Practice (Workshop on Real-World Cryptography)" (PDF). Stanford University. Retrieved 26 November 2018.CS1 maint: multiple names: authors list (link)
  3. ^ Sullivan, Bryan. "Cryptographic Agility" (PDF). Microsoft Corporation on Retrieved 26 November 2018.
  4. ^ Grimes, Roger A. (2017-07-06). "All you need to know about the move from SHA1 to SHA2 encryption". CSO Online. Retrieved 2019-05-19.
  5. ^ "Chapter 18. Fundamentals of the Public Key Infrastructure - CCNA Security 640-554 Official Cert Guide [Book]". Retrieved 2019-04-11.
  6. ^ "IBM Knowledge Center". Retrieved 2019-02-15.
  7. ^ Walker, Ivy. "Cybercriminals Have Your Business In Their Crosshairs And Your Employees Are In Cahoots With Them". Forbes. Retrieved 2019-05-19.
  8. ^ Bl, Stephanie; a (2014-05-01). "Shor's Algorithm – Breaking RSA Encryption". AMS Grad Blog. Retrieved 2019-08-09.
  9. ^ Henry, Jasmine. "3DES is Officially Being Retired". Cryptomathic. Retrieved 26 November 2018.
  10. ^ Mehmood, Asim. "What is crypto-agility and how to achieve it?". Utimaco. Retrieved 26 November 2018.
  11. ^ Chen, Lily; Jordan, Stephen; Liu, Yi-Kai; Moody, Dustin; Peralta, Rene; Perlner, Ray; Smith-Tone, Daniel. "Report on Post-Quantum Cryptography (NISTIR 8105)" (PDF). National Institute of Standards and Technology NIST. Retrieved 26 November 2018.
  12. ^ Macaulay, Tyson. "Cryptographic Agility in Practice" (PDF). InfoSec Global. Retrieved 5 March 2019.