Identity-Based Encryption

KZero Staff
Jul 27, 2023

What is Identity-Based Encryption?

Identity-based encryption (IBE) is a form of public key cryptography. It uses the person’s name, email address, or similar unique identifier to generate the public key.

One of the main advantages of IBE is that it eliminates the need for public key infrastructure (PKI) to tie public keys to real-world identities. The validity of a public key is easily verified because it’s derived from a user’s name or email.

How Does IBE Work?

IBE is a special cryptographic scheme that uses easily identifiable values for public keys. For this to work, setting up and using the system requires a different process from other types of public key cryptography. The process is:

  • Setup: The Private Key Generator (PKG) configures the encryption system and generates the master encryption keys. They then publish the master public key.
  • Public Key Creation: A user’s public key will be derived from a combination of the master public key and their identity. The user can use this information to derive their public key.
  • Key Extraction: Users will submit their desired public keys to the PKG. Using the master key, the PKG generates a private key that corresponds to that public key and sends it to the user.
  • Encryption: Encryption in public key cryptography uses the public key. Someone wishing to send an encrypted message to a user will use their identity (email address, name, etc.) and the master public key to generate the user’s public key and encrypt the message.
  • Decryption: When a user receives a message, they can decrypt it using the private key that is associated with their public key.

Benefits of IBE

IBE is designed to make public key cryptography easier to use. Some benefits that it provides include:

  • No Public Key Distribution: All users’ public keys are derived from the combination of their identity and the master public key. This makes PKI and public key distribution unnecessary because any user can compute any other user’s public key.
  • Flexibility: IBE can use any form of identity as an input to a user’s public key. This makes identities configurable to an organization’s use case.
  • Scalability: All private and public keys are based on a single master key pair. This makes the process of generating and distributing keys much more efficient.

IBE Security Concerns

IBE has significant advantages. However, it also has its downsides, such as:

  • Centralized Key Generation: All private keys are generated by the PKG. This means that the PKG knows all private keys and can decrypt any message which threatens confidentiality.
  • Single Point of Failure: The PKG is a single point of failure for security. If the master private key is compromised, then all keys in the system are compromised.


IBE is designed to make public key cryptography easier by making public keys dependent on a user’s real-world identity. While it has several advantages, it also runs the risk of centralizing power in the PKG, which is responsible for generating and distributing all private keys used within the system.

KZero Staff

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