Public key cryptographic system consists of two separate keys, one to lock or encrypt the plain text, and the other to unlock or decrypt the ciphertext. One of the key is public key and the other is a private key. The lock or encryption key of the Public Key Cryptographic system enables private communication from the public to unlocking key’s owner. The unlock or decryption key of the Public Key Cryptographic system serves as a signature verifier of documents locked by the owner of the private key. Public Key Cryptography is also called as Asymmetric Key Cryptography as it uses Asymmetric key algorithms. Public Key Cryptography is mostly used in Key agreement, Data Encryption, and Digital Signatures.

Features of Public Key Cryptography

  • A message encrypted with a recipient public key cannot be encrypted by anyone except a possessor of the matching private key. This assures confidentiality by using public Key Cryptography.
  • Example of Public key Cryptography is a locked mailbox with a mailslot.
  • Public key cryptography is used in digital signature schemes.
  • Digital signatures by public key cryptography are used for sender authentication and non-repudiation.

Advantages and Drawbacks of Public Key Cryptography

  • Advantages of Public Key Cryptography
    • A Public key algorithm does not require a secure initial exchange of one or more secret keys between the sender and receiver.
    • The use of public key algorithm allows authenticity of a message to be checked by creating a digital signature of the message using the private key, which can be verified using the public key.
    • The advantage of Public Key Cryptography is increased security and convenience
    • The public key system can be used to encrypt a secret key which is used to encrypt the bulk of a file or message.
  • Drawbacks of Public Key Cryptography
    • The speed of encryption is less in public key cryptography systems when compared to all other security systems.
    • Public key cryptography cannot be used with secret key cryptography systems.
    • Public key cryptography may be vulnerable to impersonation.