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Public-Key Encryption Structure

Explore the structure and objectives of public-key encryption, a cryptographic system that uses two separate keys for encryption and decryption. Learn about its importance in confidentiality, key distribution, and authentication.

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Public-Key Encryption Structure

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  1. Public-Key Encryption Structure Network Security

  2. Public-Key Encryption Structure Objectives of the Topic • After completing this topic, a student will be able to • explain structure of Public-key encryption.

  3. Public-Key Encryption Structure Figures and material in this topic have been adapted from • “Network Security Essentials : Applications and Standards”, 2014, by William Stallings.

  4. Public-Key Encryption Structure • Public-key encryption, first publicly proposed by Diffie and Hellman in 1976.

  5. Public-Key Encryption Structure • Public-key algorithms are based on mathematical functions rather than on simple operations on bit patterns, such as are used in symmetric encryption algorithms.

  6. Public-Key Encryption Structure • More important, public-key cryptography is asymmetric, involving the use of two separate keys—in contrast to the symmetric conventional encryption, which uses only one key.

  7. Public-Key Encryption Structure • The use of two keys has profound consequences in the areas of confidentiality, key distribution, and authentication.

  8. Public-Key Encryption Structure Structure • A public-key encryption scheme has six ingredients. • Plaintext: This is the readable message or data that is fed into the algorithm as input.

  9. Public-Key Encryption Structure • Encryption algorithm:The encryption algorithm performs various transformations on the plaintext.

  10. Public-Key Encryption Structure • Public and private key: This is a pair of keys; one is used for encryption, the other is used for decryption. • The exact transformations performed by the encryption algorithm depend on the public or private key.

  11. Public-Key Encryption Structure • The public key of the pair is made public for others to use, while the private key is known only to its owner.

  12. Public-Key Encryption Structure • Ciphertext: This is the scrambled message produced as output. • It depends on the plaintext and the key. • For a given message, two different keys will produce two different ciphertexts.

  13. Public-Key Encryption Structure • Decryption algorithm: This algorithm accepts the ciphertext and the matching key and produces the original plaintext.

  14. Public-Key Encryption Structure • A general-purpose public-key cryptographic algorithm relies on one key for encryption and a different but related key for decryption.

  15. Public-Key Encryption Structure Working • 1. Each user generates a pair of keys to be used for the encryption and decryption of messages.

  16. Public-Key Encryption Structure • 2. Each user places one of the two keys in a public register or other accessible file. • This is the public key. The companion key is kept private. • Each user maintains a collection of public keys obtained from others.

  17. Public-Key Encryption Structure • 3. If Bob wishes to send a private message to Alice, Bob encrypts the message using Alice’s public key.

  18. Public-Key Encryption Structure • 4. When Alice receives the message, she decrypts it using her private key. • No other recipient can decrypt the message because only Alice knows Alice’s private key.

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