What Is a Cryptography Algorithm?

Written by Coursera Staff • Updated on

Explore the inner workings of a cryptography algorithm and its impact on data integrity and privacy.

[Featured Image]: A technician standing in a server room secures data with advanced cryptography algorithms.

Key takeaways

Cryptographic algorithms are the mathematical formulas that allow you to encrypt and decrypt data. Here are some important facts to know:

  • Cryptographers use two main types of algorithms: symmetric and asymmetric.

  • While symmetric-key cryptography algorithms are faster and more efficient, asymmetric-key cryptography algorithms offer greater security.

  • You can prepare for a career in cryptography by building a strong foundation in computer science, cybersecurity, or math.

Learn how cryptography algorithms help maintain confidentiality in digital communication. Afterward, enroll in Google’s Cybersecurity Professional Certificate to learn how to safeguard networks and devices against unauthorized access and cyberattacks using security information and event management (SIEM) tools. 

Why is a cryptography algorithm? 

A cryptography algorithm is the mathematical formula that enables the encryption and decryption of data. The most basic cryptosystems take plaintext (an unencrypted message) as input and, with one or more encryption keys, convert it into ciphertext that is impossible to decode without a decryption key. 

The use of cryptography to conceal messages spans thousands of years and remains vital even today for ensuring trust and privacy in online interactions or transactions. For example, a cryptographic algorithm can transform sensitive data like a numeric PIN or password into a string of random special characters such as “%$&”, keeping the information secure during an online purchase. 

What are the 4 pillars of cryptography?

Confidentiality, integrity, non-repudiation, and authenticity make up the four foundational pillars of cryptography. Each of these four pillars targets a specific aspect of information security.  

- Confidentiality: Ensures encrypted information is accessible only to its intended recipient

- Integrity: Ensures encrypted data remains unchanged during storage or transit

- Non-repudiation: Prevents the sender of encrypted data from denying their intent to share the information

- Authenticity: Verifies the identities of both the sender and receiver, as well as the source and destination of data 

Read more: Data Stewardship vs. Data Governance: What’s the Difference?

Types of cryptography algorithms 

Cryptographers typically use two main types of algorithms: symmetric and asymmetric. While symmetric-key cryptography algorithms are faster and more efficient, asymmetric-key cryptography algorithms offer greater security. Below is a breakdown of both types.

Symmetric-key cryptography algorithm

Symmetric-key cryptography algorithms rely on a single key for both encryption and decryption. The sender and receiver must share access to this private key to transmit information securely. Symmetric cryptography is alternatively referred to as private-key cryptography. Due to its speed, symmetric cryptography is well-suited for bulk data encryption.

Asymmetric-key cryptography algorithm

Asymmetric-key cryptography algorithms operate with two keys—a public key for encryption and a private key for decryption. You can share the public key, but you must keep the private key confidential. Also known as public-key cryptography, this method adds an extra layer of protection by separating the encryption and decryption processes. However, this comes with a tradeoff of reduced efficiency or speed. 

What is the RSA algorithm in cryptography?

RSA, short for Rivest Shamir Adleman, is the most widely used algorithm in asymmetric cryptography. Introduced in 1997, RSA takes its name from the initials of its inventors’ surnames: Ron Rivest, Adi Shamir, and Leonard Adleman. 

In line with the principles of asymmetric cryptography, RSA uses one key to encrypt data and another to decrypt it. However, what sets it apart is that encryption can be done by either the public or private key, with the counterpart key performing the decryption. 

The complete RSA process, including the generation of public and private keys, followed by encryption and decryption, is mathematically complex. At the core of RSA is the factorization of large integers. It involves selecting two large prime numbers as part of the key pair, making factorization difficult. The challenge of factoring large integers into primes is what gives RSA its security. Essentially, large prime numbers greatly increase the computational effort required to guess or deduce the keys.

Digital certificates, including secure sockets layer (SSL), use RSA to confirm the identity of organizations or individuals behind websites. 

What is a hash algorithm in cryptography?

A hash algorithm converts an input string of variable length into a fixed-length output string,

known as a message digest or hash value. Here, the input represents the plaintext, while the resulting hash functions as the ciphertext. Any alteration to the original data changes the hash value, making it possible to detect modifications. Furthermore, hash algorithms are one-way by design. Given only the hash value, it is impossible to reconstruct the original data. In effect, plain text acts as its own key. 

The Message Digest Algorithm 5 (MD5) is a widely used hash algorithm. This hash function generates a 128-bit hash from a string of any length and is commonly used to verify file integrity. 

Who uses cryptography algorithms?

Individuals, organizations, and government agencies all use cryptography to safeguard sensitive information. For example, messaging platforms like WhatsApp encrypt conversations to prevent interception. A virtual private network (VPN) enables you to access the internet through a private, encrypted tunnel that hides your location and personal data. Select cryptographic solutions approved by the National Institute of Standards and Technology (NIST) secure smartphones, ATMs, and even federally classified data. 

Pros and cons of cryptography algorithms

Cryptography plays a vital role in cybersecurity, supporting secure data exchange and identity verification. Outlined below are some notable advantages and limitations of a cryptography algorithm. 

Advantages

Cryptographic algorithms work with security protocols to ensure that sensitive information stays confidential and tamper-proof as it moves across networks. Like security protocols, cryptography algorithms are routinely updated to remain effective against evolving cyber threats. A few perks of implementing cryptography algorithms are as follows: 

  • Cryptography algorithms help verify electronic signatures, reducing the risk of identity theft or fraud. 

  • Encryption protects firms’ voice over internet protocol (VoIP) calls against eavesdropping, ensuring confidentiality in business communications. 

  • With cryptography algorithms, security platforms can verify passwords without maintaining a plaintext database that could be vulnerable to attacks.

Disadvantages

The effectiveness of your cryptographic algorithms depends on proper implementation, maintenance, and key management. Even strong algorithms can become weak points if mishandled or not updated in response to emerging technologies. Cryptography algorithms become increasingly susceptible to vulnerabilities when implemented by non-experts. Other downsides to using these algorithms are: 

  • Quantum computers, in time, may efficiently perform complex mathematical calculations, putting conventional cryptography algorithms like RSA at risk. 

  • A single compromised public or private key can expose a firm to hefty fines, reputational harm, and regulatory actions.

 

  • A server or database breach can lead to theft of any stored keys. 

How to get started with cryptography algorithms

The traditional route to learning cryptography involves pursuing a bachelor’s degree in computer science, cybersecurity, or math, all of which can help you build the technical skills needed for creating and cracking complex codes. 

If you’re a professional and prefer to learn without a formal degree, courses and specializations are excellent options. The University of Colorado’s Applied Cryptography Specialization, for instance, offers insights into classical cryptographic algorithms. The course also covers message authentication codes, digital signatures, key management and distribution, and other fundamental cryptographic primitives and protocols.

You can supplement your learning with GitHub’s curated list of cryptography resources and links. 

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