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Cryptography

Cryptography is the mathematical discipline of protecting information by transforming it so that unauthorized parties cannot read it, misuse it, or alter it undetected. Modern cryptographic systems support confidentiality, data integrity and authentication through tools such as symmetric encryption, public-key algorithms, hash functions and digital signatures. Their security depends not only on algorithm design but also on sound implementation and careful management of cryptographic keys.

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14 October 2026
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This article was researched and drafted with AI assistance and checked by an automated review pass. It is not guaranteed to be accurate — verify important facts against the references below.

Purpose and scope

Cryptography uses mathematical methods to protect information. Depending on how a system is designed, it can conceal a message, help detect unauthorized changes, or provide evidence about the origin of data. Cryptography is closely related to cryptanalysis, the study of how cryptographic systems can be analyzed or broken; together these disciplines are often discussed as cryptology. Cryptography is a foundation of information security, but it is one part of a larger system that also depends on trustworthy software, devices, procedures and people.

Core methods

Symmetric cryptography uses the same secret key for an operation and, when applicable, to reverse it—for example, to encrypt and decrypt data. It is commonly used to protect large amounts of information, but communicating parties must have a secure way to obtain the key. Asymmetric, or public-key, cryptography uses a related public and private key: depending on the algorithm, the public key can be used to encrypt data for its owner or verify a signature made with the corresponding private key. Cryptographic hash functions map data of any length to a fixed-length digest; they are useful in integrity checks but are not encryption and do not, by themselves, prove who created a message. Digital signatures use cryptographic operations to help verify a signatory and detect changes to signed data, but a signature alone does not keep the data secret.

From ciphers to digital networks

People have used concealed writing and ciphers since antiquity, but the scale and purpose of cryptography changed with electrical communications and digital computing. For much of its history, systems were implemented by hand or with mechanical devices. In 1976, Whitfield Diffie and Martin Hellman published a paper that explored public-key cryptography and ways to establish keys over public channels, an important shift in how parties could begin secure communication without first sharing a secret key in person. In the United States, the National Bureau of Standards issued the Data Encryption Standard as a federal standard in 1977. NIST later coordinated an open international competition to select the Advanced Encryption Standard (AES); it published the standard in 2001. These developments helped cryptographic methods become widely usable in commercial and networked computing.

Uses and limitations

Cryptographic methods are used to protect data in storage and transit, secure online transactions and communications, and authenticate software or digital documents. Modern systems often combine different methods: encryption can protect confidentiality, while hashes and signatures can help verify integrity and origin. None of these functions guarantees that an entire system is safe. Weak algorithms, flawed software, compromised devices or mishandled keys can undermine protection, so organizations use key-management processes covering how keys are generated, distributed, stored, used and retired. Standards also evolve as analysis and computing capabilities change, prompting transitions to more robust algorithms or keys when older ones no longer provide adequate protection.

Key facts

Main goals
Cryptographic techniques can support confidentiality, integrity and authentication.
Symmetric cryptography
Uses a shared secret key for its operation and, when applicable, to reverse it.
Asymmetric cryptography
Uses related public and private keys for encryption, key establishment or digital signatures, depending on the algorithm.
Hash functions
Convert data of arbitrary length into a fixed-length digest; hashing is not encryption.
Key management
Secure generation, distribution, storage, use and retirement of keys are essential parts of cryptographic security.

Timeline

  1. 1976

    Whitfield Diffie and Martin Hellman published “New Directions in Cryptography,” exploring public-key cryptography and key exchange over public channels.

  2. 1977

    The U.S. National Bureau of Standards issued the Data Encryption Standard as Federal Information Processing Standard 46.

  3. 2001

    NIST published the Advanced Encryption Standard (AES) as FIPS 197.

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References

  1. 1.
    Cryptography

    National Institute of Standards and Technology (NIST) · other · reliability: high · retrieved 14 October 2026

    Supports: A concise definition of cryptography and examples of its role in electronic communications and commerce.

  2. 2.
    cryptography - Glossary

    NIST Computer Security Resource Center (CSRC) · other · reliability: high · retrieved 14 October 2026

    Supports: Cryptography's role in confidentiality, integrity, authentication and related information-security services.

  3. 3.
    Symmetric Cryptography - Glossary

    NIST Computer Security Resource Center (CSRC) · other · reliability: high · retrieved 14 October 2026

    Supports: The shared-secret-key model used by symmetric cryptographic algorithms.

  4. 4.
    asymmetric cryptography - Glossary

    NIST Computer Security Resource Center (CSRC) · other · reliability: high · retrieved 14 October 2026

    Supports: The public-key model using separate, related keys for encryption or signatures and their corresponding decryption or verification.

  5. 5.
    public key - Glossary

    NIST Computer Security Resource Center (CSRC) · other · reliability: high · retrieved 14 October 2026

    Supports: Uses of a public key, including signature verification, encryption and key agreement, depending on the algorithm.

  6. 6.
    hash function - Glossary

    NIST Computer Security Resource Center (CSRC) · other · reliability: high · retrieved 14 October 2026

    Supports: The fixed-length output of a hash function and security properties such as resistance to collisions and preimage attacks.

  7. 7.
    digital signature - Glossary

    NIST Computer Security Resource Center (CSRC) · other · reliability: high · retrieved 14 October 2026

    Supports: Digital signatures can provide origin authentication and data integrity, but not confidentiality.

  8. 8.
    FIPS 186-5, Digital Signature Standard (DSS)

    National Institute of Standards and Technology (NIST) · other · reliability: high · retrieved 14 October 2026

    Supports: NIST's current digital-signature standard and the intended authenticity and integrity functions of a signature.

  9. 9.
    Cryptology - Ancient, Codes, Ciphers

    Encyclopaedia Britannica · other · reliability: high · retrieved 14 October 2026

    Supports: An overview of cryptology's long history and development from early ciphers to later technologies.

  10. 10.
    New Directions in Cryptography

    IEEE Transactions on Information Theory · other · reliability: high · retrieved 14 October 2026

    Supports: Diffie and Hellman's 1976 paper on public-key cryptography, key distribution and digital authentication.

  11. 11.
    Cryptography

    NIST Computer Security Resource Center (CSRC) · other · reliability: high · retrieved 14 October 2026

    Supports: NIST's historical account of the DES standard, the public development of AES, and the spread of cryptography in computing.

  12. 12.
    FIPS 197, Advanced Encryption Standard (AES)

    National Institute of Standards and Technology (NIST) · other · reliability: high · retrieved 14 October 2026

    Supports: The AES standard, first published in 2001, and the AES block-cipher family.

  13. 13.
    Key Management

    NIST Computer Security Resource Center (CSRC) · other · reliability: high · retrieved 14 October 2026

    Supports: Guidance covering the protection and management of cryptographic keys.

  14. 14.
    Recommendation for Key Management: Part 1 – General

    National Institute of Standards and Technology (NIST) · other · reliability: high · retrieved 14 October 2026

    Supports: Detailed best practices and lifecycle considerations for cryptographic key management.

References are suggested by the research engine and may be incomplete. Unverified URLs are omitted rather than guessed.

Article history

  1. Version 114 October 2026 · EditorCreated by Zapia