Which encryption system generates a public key automatically on demand?

Which encryption system generates a public key automatically on demand?

• A. RSA encryption
• B. Symmetric key encryption
• C. Identity-based encryption (IBE)
• D. Quantum key distribution

Answer: (C)

The ability to derive a public key automatically from a user’s identity is what identity-based encryption provides. In IBE, a public key is not a separately distributed certificate or key pair. Instead, a user’s public key is determined by their unique identity (for example, an email address) using public system parameters. Anyone can compute that public key on demand, without contacting a certificate authority, which is why encryption can proceed immediately with the recipient’s identity. The actual private key, needed to decrypt, is issued by a trusted authority called the Private Key Generator after verifying the user’s identity. This setup removes the need for managing and distributing certificates to bind identities to keys. In contrast, RSA relies on explicit key pair generation and distribution, symmetric encryption uses a shared secret rather than public keys, and quantum key distribution focuses on exchanging keys through quantum properties rather than deriving public keys from identities.

The ability to derive a public key automatically from a user’s identity is what identity-based encryption provides. In IBE, a public key is not a separately distributed certificate or key pair. Instead, a user’s public key is determined by their unique identity (for example, an email address) using public system parameters. Anyone can compute that public key on demand, without contacting a certificate authority, which is why encryption can proceed immediately with the recipient’s identity. The actual private key, needed to decrypt, is issued by a trusted authority called the Private Key Generator after verifying the user’s identity. This setup removes the need for managing and distributing certificates to bind identities to keys. In contrast, RSA relies on explicit key pair generation and distribution, symmetric encryption uses a shared secret rather than public keys, and quantum key distribution focuses on exchanging keys through quantum properties rather than deriving public keys from identities.