What Is a Private Key & How Does It Work?

Encryption is a foundational tool to secure data from unauthorized disclosure and protect privacy for users and businesses.

What is private key cryptography? It is a form of encryption that uses a single private key for data encryption and decryption.

What Is a Private Key?

A private key is a cryptographic key used in an encryption algorithm to both encrypt and decrypt data. These keys are used in both public and private encryption:

  • In private key encryption, also known as symmetric encryption, the data is first encrypted using the private key and then decrypted using the same key. This means anyone with access to the private key can decrypt the data.
  • In a public-key system, also known as asymmetric encryption, data is encrypted with a widely-distributed public key. This data can only be decrypted with a corresponding private key that the user keeps secret. This makes it possible for anyone to send encrypted data to the owner of the private key, who can then decrypt it using their private key.

In both systems, the private key is kept secret and not shared with anyone else. It is used to decrypt and read encrypted messages. However, in a symmetric system, there is only a single key (the private key). In asymmetric systems, a message uses the public key to encrypt data that must then be decrypted using a private key.

Private key encryption is often used to encrypt data stored or transmitted between two parties. For example, when you log in to a website using a username and password, the password is often encrypted using a private key before it is transmitted to the web server.

While private key encryption is a simple and efficient method, it has limitations regarding secure data transmission over a network. Since the same key is used for encryption and decryption, two parties must securely exchange the key before data can be encrypted and transmitted. If an unauthorized party intercepts the key, they can easily decrypt the data.

Private vs. Public Key Encryption

As previously discussed, public and private key encryption differ on how they create and distribute keys. As such, there are several different applications of each approach.

Some examples of private key encryption include:

  • Block Ciphers: Block ciphers encrypt data in fixed-size blocks and typically use a single, private key. Examples of block ciphers include Advanced Encryption Standard (AES), Blowfish, and Triple DES.
  • Stream Ciphers: Stream ciphers encrypt data continuously and are commonly used in real-time communication, such as voice or video streaming.
  • Hash Functions: Hash functions are one-way functions that generate a fixed-size output from any input, allowing data recipients to verify the integrity of the data. Examples of hash functions include SHA-256 and MD5.

Some examples of public key encryption include:

  • Rivest-Shamir-Adleman (RSA): RSA was developed by Ron Rivest, Adi Shamir, and Leonard Adleman as an asymmetric encryption standard used for encrypting data as well as for digital signatures and key exchange.
  • Elliptic Curve Cryptography (ECC): ECC is a modern asymmetric key encryption algorithm becoming increasingly popular for key exchange, digital signatures, and encryption.
  • Diffie-Hellman: Diffie-Hellman is a key exchange algorithm that is used to securely exchange keys for common applications like secure communication and virtual private networks (VPNs).
  • Digital Signature Algorithm (DSA): DSA is an asymmetric key encryption algorithm that is used for digital signatures. It is commonly used in programs like secure email and financial management.

Additionally, some applications use public and private key encryption combinations to secure data communications. Some of these include:

  • Pretty Good Privacy (PGP): This uses both private and public key encryption to ensure the confidentiality and integrity of data. It uses symmetric-key encryption to encrypt the data and asymmetric-key encryption to securely exchange the symmetric key between the sender and the recipient.
  • Secure Sockets Layer (SSL): SSL is a cryptographic protocol that establishes a secure and encrypted connection between a web server and a web browser. SSL provides a secure method of data transmission over the internet by ensuring the confidentiality and integrity of data exchanged between the client and server.

What Is Private Key Management?

One of the most critical points of security failure around private key encryption (and encryption more broadly) is managing and protecting keys. If a key is compromised, then any data that uses that key is effectively open to the public.

This presents a problem, however, in that keys must be stored and, in some cases, transmitted so that users can decrypt information. Therefore, effective private key management is critical to maintaining the security and integrity of sensitive information.

Here are some best practices for private key management:

  • Secure Storage: Private keys should be stored in a secure location, such as a hardware security module (HSM), a smart card, or a secure file system. The storage should be physically and logically secure, and access should be restricted to authorized personnel only.
  • Key Rotation: Private keys should be rotated regularly to prevent any potential compromise. This can be done by generating a new key and phasing out the old one.
  • Access Control: Access to private keys should be strictly controlled, and only authorized personnel should be granted access. The access should be logged and monitored for any unauthorized activity.
  • Key Destruction: Private keys should be securely destroyed when they are no longer needed to prevent any potential compromise. This can be done by using a secure key destruction method, such as cryptographic erasure.

Generating and Finding Your SSL Key

The process of generating keys will differ depending on the application used and your proximity to key and encryption administration.

For example, the admin of an SSL server can generate a certificate using the software on hand. Likewise, the admin can use the URL they manage to request SSL certificates (which will generate public and private keys) from a certificate authority. These keys would be located on the server on which they are created… but aren’t available for general access.

Likewise, an application that uses PGP (like an email service) may create and store private keys in a local directory–again, in a location where normal users should not be able to access them.

The reality is that the key must remain private whenever a private key is generated. Therefore, these keys are often encrypted and protected behind strong authentication and access standards.

What Are the Benefits of Private Key Encryption?

There are several benefits of private key encryption, including:

  • Performance: Private key encryption algorithms are easier to implement. Furthermore, these algorithms can encrypt and decrypt larger data blocks faster than their public counterparts.
  • Authentication: Private key encryption can be used for authentication by providing a digital signature that verifies the identity of the sender. Furthermore, different forms of authentication (passwords, etc.) can be used to authenticate a recipient before decryption.
  • Integrity: Private key encryption can ensure data integrity through message digests or one-way hashes by detecting any modifications or tampering that may have occurred during transmission.

1Kosmos identity Management and Encryption

At the heart of the 1Kosmos BlockID is decentralized, encrypted blockchain technology serving as a private, encrypted ledger. This ledger uses private and public keys to encrypt user information. These keys are generated and controlled by the user via the app without their needing to directly manage these keys.

1Kosmos also includes features like:

  • SIM Binding: The BlockID application uses SMS verification, identity proofing, and SIM card authentication to create solid, robust, and secure device authentication from any employee’s phone.
  • Identity-Based Authentication: We push biometrics and authentication into a new “who you are” paradigm. BlockID uses biometrics to identify individuals, not devices, through credential triangulation and identity verification.
  • Cloud-Native Architecture: Flexible and scalable cloud architecture makes it simple to build applications using our standard API and SDK.
  • Identity Proofing: BlockID verifies identity anywhere, anytime and on any device with over 99% accuracy.
  • Privacy by Design: Embedding privacy into the design of our ecosystem is a core principle of 1Kosmos. We protect personally identifiable information in a distributed identity architecture and the encrypted data is only accessible by the user.
  • Private and Permissioned Blockchain: 1Kosmos protects personally identifiable information in a private and permissioned blockchain and encrypts digital identities and is only accessible by the user. The distributed properties ensure that there are no databases to breach or honeypots for hackers to target.
  • Interoperability: BlockID can readily integrate with existing infrastructure through its 50+ out of the box integrations or via API/SDK.

Sign up for the email newsletter and read more about our distributed ledger for identity here.

FIDO2 Authentication with 1Kosmos
Read More
Meet the Author

Javed Shah

Former Senior Vice President Of Product Management

Javed has spent his entire twenty year career designing and building blockchain and identity management solutions. He has led large customer facing pre-sales teams, led product management for identity management platforms like the ForgeRock Identity Platform and the ForgeRock Identity Cloud. Javed has an MBA from UC Berkeley.