What Is A Public Key In Crypto?

Last updated Feb 21, 2024 | 04:59 PM UTC
  • Public key is used for encryption in cryptography
  • Whitfield Diffie and Martin Hellman are pioneers of public-key cryptography
  • Symmetric and asymmetric keys are the two main types of keys in cryptography
  • Public key cryptography provides different benefits including confidentiality, integrity, and authenticity

The terms and concepts used in crypto transactions must be thoroughly understood before engaging in any transactions. In order to ensure the security of transactions and the overall cryptocurrency system, public and private keys are fundamental tools.

An encryption method that uses a public key encrypts data. It is produced by computer programs or made available by reliable sources, and third parties can access it through directories or repositories that are open to the public.

In this article, you will learn everything there is to know about public keys in cryptography, including how they work, and what advantages they might have.

Public Key, Explained  

A public key is an essential element of public-key cryptography. It is a distinct number that is produced as a component of a pair of cryptographic keys that also includes a corresponding private key. The public key is available to everyone and is freely shared.

The public key is used for encryption in cryptography. Anyone can use it to encrypt data or a message using the recipient's public key. Only the associated private key, which is solely owned by the receiver, can be used to decrypt the data after encryption and access the original message.

Public keys have a number of significant characteristics. They are mathematically linked to the associated private keys, ensuring that only the corresponding private key may decode data encrypted with a given public key. A level of validity is also provided by public keys because they may be used to validate digital signatures produced with the corresponding private key.

Public keys are frequently used in many different contexts, such as encrypted communication, digital signatures, and cryptocurrency exchanges. They are a vital part of the infrastructure that supports safe and reliable digital interactions.

Algorithms that ensure secure encryption in public-key cryptography

Public-key cryptography uses a variety of techniques to enable secure digital signatures and encryption. The Rivest-Shamir-Adleman (RSA) algorithm, the Digital Signature Algorithm (DSA), and elliptic curve cryptography (ECC) are three noteworthy algorithms that are frequently used in public key cryptography.

The RSA algorithm, which bears the names of its creators, is frequently employed for digital signatures and secure communication. To create the key pair, it makes use of the mathematical features of huge prime integers. Large composite numbers are challenging to factor into their prime factors, which is how RSA achieves its security.

DSA is a popular algorithm for producing and validating digital signatures. It offers a way to check the legitimacy and consistency of digital materials. DSA generates a signature using mathematical formulas that may be validated using the appropriate public key.

Public-key cryptography alternatives like ECC provide robust security with shorter key lengths than RSA and DSA. The mathematical characteristics of elliptic curves, on which ECC is based, offer a secure basis for producing key pairs and carrying out cryptographic operations.

These methods are essential for the creation, administration, and use of public keys in a variety of cryptographic applications. They offer the fundamental building blocks for digital signatures, secure communication, and the encryption of private data.

History Of Public-Key Cryptography

Whitfield Diffie and Martin Hellman, two researchers, were the pioneers of public-key cryptography in the 1970s. By presenting a technique for secure key exchange without the requirement for a shared secret key, their seminal article on "New Directions in Cryptography" revolutionized the concept of cryptography.

Public key history

It wasn't until 1977 that Ron Rivest, Adi Shamir, and Leonard Adleman published the RSA algorithm. The National Security Agency (NSA) and the National Institute of Standards and Technology (NIST) created the DSA in the 1980s as a standard for digital signatures. ECC became a viable alternative to RSA and DSA in the late 1980s and early 1990s.

Public-key cryptography has now evolved into a crucial component of contemporary communication and digital security. Numerous applications, including secure internet communication, digital signatures, secure key exchange protocols, and secure payment systems, have widely adopted it. In the digital age, secure and private communication has been made possible by the ongoing developments in public-key cryptography.

How Public Key Works 

A public key and a private key, which are related mathematically, are used in public-key cryptography, also referred to as asymmetric cryptography. While the private key is kept secret and is used for decryption, the public key is used for encryption and can be freely shared with others.

The recipient's public key is used to encrypt the message when someone wishes to send them a secure message. Only the recipient's unique private key, which corresponds to the recipient's public key, can be used to decrypt the encrypted communication. This makes sure that even if the message is intercepted during transit, only the intended receiver may read it.

In a similar way, the sender's private key is used to establish digital signatures. The sender uses their private key to encrypt a hash, or unique digital fingerprint, of the message. The digital signature is made up of the encrypted hash and the original message. 

The recipient can then decrypt the digital signature and check the message's integrity and authenticity using the sender's public key. If the computed hash of the received message matches the decrypted hash, it is certain that the message was not altered and came from the sender.

Public-key cryptography's security is reliant on the computational difficulty of specific mathematical puzzles, like factoring big integers or resolving elliptic curve equations. It is very challenging for anyone to derive the private key from the public key since these difficulties are computationally infeasible to solve in a reasonable amount of time.

In a variety of applications, such as secure messaging, secure surfing, digital signatures, and secure transactions, public-key cryptography offers a safe and effective approach to creating secure communication, confirming identities, and ensuring data integrity.

To send and receive data via asymmetric cryptography, one needs to follow the below steps:

  • Each participant creates a public and private key
  • The sender and receiver exchange their public keys
  • The sender's information is encrypted via the recipient's public key
  • Encrypted data goes to the recipient
  • The recipient decodes the message via their private key


Types Of Cryptography Keys 

Symmetric and asymmetric keys are the two main types of keys used in cryptography.

Symmetric Keys

A single shared secret key is used in symmetric key cryptography, commonly referred to as secret key cryptography, for both encryption and decoding. Both the sender and the recipient use the same key. Although it is a quick and effective solution, it needs the shared key to be distributed securely.

Asymmetric Keys

Asymmetric key cryptography, commonly referred to as public-key cryptography, employs a set of two keys, a public key and a private key, which are connected mathematically. While the private key is required for decryption, the public key is used for encryption. 

Only the appropriate private key can be used to decrypt messages that have been encrypted with the public key. This makes it possible to communicate securely without having to disclose a secret key.

There are more cryptographic keys that are used for certain purposes in addition to these two major types:

Types of Keys

Digital Signature Keys

A private key is used to create a distinct digital signature that can be validated using the associated public key in digital signatures. They make sure that digital documents and messages are authentic and reliable.

Key Exchange Keys

Asymmetric keys are used in key exchange protocols to safely exchange symmetric keys between two parties. This makes it possible to communicate securely using symmetric key cryptography without using pre-shared keys.

Hashing Keys

From input data, hash functions produce fixed-length, distinctive hash values. Hashing keys are used to validate data consistency, authenticate passwords, and safely store sensitive data, even though they are not directly used for encryption or decryption.

In cryptography, each type of key has a distinct function that is essential to preserving the confidentiality, integrity, and validity of data across a range of cryptographic applications.

What Is Public Key Encryption?

Asymmetric encryption, commonly referred to as public key encryption, uses two keys that are mathematically related: a public key and a private key. While the private key is required for decryption, the public key is used for encryption. This method offers a safe way to send data over unreliable networks.

In public key encryption, the sender encrypts the message using the recipient's public key. The recipient's corresponding private key is the only way to decrypt a communication after it has been encrypted. The private key is kept private and only known to the receiver, but the public key is, as the name implies, widely dispersed and available to everyone.

Numerous applications, including secure communication protocols, digital signatures, safe online transactions, and data encryption in cloud computing, make extensive use of public key encryption. It serves as the cornerstone of safe and reliable digital communication.

Secure Communication Protocols

To create secure connections between clients and servers, secure communication protocols like HTTPS, SSL/TLS, and SSH use public key encryption. It guarantees that the information sent over the network is secure and shielded from unauthorized access.

Digital Signatures

Public-key encryption makes it possible to create digital signatures. A mathematical formula known as a digital signature ensures the reliability, integrity, and non-repudiation of digital documents. It enables the recipient to confirm the sender's identity and guarantees that the document's content hasn't been altered.

Safe Online Transactions

Online banking and e-commerce transactions that are secure use public key encryption to protect sensitive data like credit card numbers and personal information. It makes sure that the data is encrypted while being transmitted, guarding against eavesdropping and unauthorized access.

Data Encryption In Cloud Computing

To encrypt sensitive data stored in the cloud, public key encryption is used. By doing this, you can make sure that even if your data is stolen or seen by someone else, it will still be encrypted and impossible to decrypt without the right private key.

Benefits of Public Key Encryption

Everyone who uses public keys should be aware of the advantages and disadvantages of public key encryption. Public key cryptography provides different benefits in an open blockchain network. This includes:

  • Confidentiality: Blockchain ensures the confidentiality of shared data. Linked public and private keys keep the sent data safe and protected from unallowed parties. This is possible thanks to data encryption via a public key and data decryption via a private key. 
  • Integrity: Encryption ensures the integrity of information by allowing only the sender and the intended recipient to access the data. It prevents any unauthorized intermediaries from tampering with the content, guaranteeing the privacy and security of the communication.
  • Authenticity: Public-key encryption ensures authenticity of transactions. Each transaction is signed by digital signatures, which makes it impossible to forge an identity. This builds more trust among users.


Disadvantages of Public-Key Encryption

Public-key encryption has many benefits, but you should also be aware of its flaws:

  • Capacity: Mathematical algorithms can encrypt/decrypt data up to a limited size. In the case of large data amounts, the algorithm will be slow. This will also require more computational power. 
  • Security: If third parties have access to your private key, your information will be exposed. 
  • Lost key: When a node loses a private key, it won't be able to make transactions from the identical public address again. It will also lose access to the encrypted data.



What is a public key in cryptography?

Public key cryptography is another name for a pair of keys (a public and a private key). While the public key is accessible, its corresponding private key is secret.

What is the purpose of public keys in crypto?

A public key allows customers to obtain cryptocurrency. A cryptographic code is matched with a private key.

What is the format of a public key in crypto?

Public keys include an identification byte, plus two coordinates - 32-byte X, and a 32-byte Y.

Where is the public key located?

The public key is usually maintained on a public key infrastructure server. Its purpose is to encrypt data before sending them over the web.

What are the risks of utilizing a public key in crypto?

Using public keys also poses certain risks, such as capacity issues, security, and loss of access.