Message digest & digital signature
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This document discusses message digests and digital signatures. It begins by introducing message digests or hashes, which represent a fixed-length string that uniquely identifies a message. It then discusses digital signatures, where a message digest is encrypted with a sender's private key. This allows a recipient to verify the integrity and authenticity of the message by decrypting the signature with the sender's public key and comparing it to a new message digest. The document outlines the steps for digital signatures and notes they can provide integrity, authentication, and non-repudiation, but not privacy. It explains each of these properties in more detail.
Message digest & digital signature
- 1. Message Digest & Digital Signature. Presented By Lamack Jose (Roll No 16) Dinesh Kodam (Roll No 34) Manoj Patil (Roll No 36)
- 2. Concept of Hash (Message Digest) 2
- 3. Concept of Hash (Message Digest) 3
- 4. Idea of a Message Digest 4
- 5. Idea of a Message Digest 5
- 6. Requirement of a Message Digest 6
- 11. Steps for the process 11
- 15. Properties of Digital Signatures • Digital signature does not provide privacy. If there is a need for privacy, another layer of encryption/decryption must be applied. • 1. 2. 3. Digital signatures can provide Integrity, Authentication, and Nonrepudiation. 15
- 16. Properties of Digital Signatures 16
- 17. Properties of Digital Signatures 1. 2. Integrity The integrity of a message is preserved because if Eve intercepted the message and partially or totally changed it, the decrypted message would be unreadable. Authentication We can use the following reasoning to show how a message can be authenticated. If Eve sends a message while pretending that it is coming from Alice, she must use her own private key for encryption. The message is then decrypted with the public key of Alice and will therefore be nonreadable. Encryption with Eve's private key and decryption with Alice's public key result in garbage. 17
- 18. Properties of Digital Signatures 3. Nonrepudiation Digital signature also provides for nonrepudiation. Bob saves the message received from Alice. If Alice later denies sending the message, Bob can show that encrypting and decrypting the saved message with Alice's private and public key can create a duplicate of the saved message. Since only Alice knows her private key, she cannot deny sending the message. 18