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    Muhammad Hammad Digital Signatures

    Uploaded by

    Osama Yaqoob
    This document provides an overview of digital signatures including: - What digital signatures are and their purpose of authenticating documents digitally through mathematical algorithms instead of pen and paper. - The digital signature process which involves generating public and private keys, creating a signature by signing a message with the private key, and verifying the signature with the public key. - How the Diffie-Hellman key exchange algorithm securely exchanges cryptographic keys over a public channel and was an early example of public key exchange implemented in cryptography.

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    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd

    Muhammad Hammad Digital Signatures

    Uploaded by

    Osama Yaqoob
    32 views17 pages
    This document provides an overview of digital signatures including: - What digital signatures are and their purpose of authenticating documents digitally through mathematical algorithms instead of pen and paper. - The digital signature process which involves generating public and private keys, creating a signature by signing a message with the private key, and verifying the signature with the public key. - How the Diffie-Hellman key exchange algorithm securely exchanges cryptographic keys over a public channel and was an early example of public key exchange implemented in cryptography.

    Original Description:

    block chain

    Original Title

    BlockchainTechnologyLecture10

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    This document provides an overview of digital signatures including: - What digital signatures are and their purpose of authenticating documents digitally through mathematical algorithms instead of pen and paper. - The digital signature process which involves generating public and private keys, creating a signature by signing a message with the private key, and verifying the signature with the public key. - How the Diffie-Hellman key exchange algorithm securely exchanges cryptographic keys over a public channel and was an early example of public key exchange implemented in cryptography.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    32 views17 pages

    Muhammad Hammad Digital Signatures

    Uploaded by

    Osama Yaqoob
    This document provides an overview of digital signatures including: - What digital signatures are and their purpose of authenticating documents digitally through mathematical algorithms instead of pen and paper. - The digital signature process which involves generating public and private keys, creating a signature by signing a message with the private key, and verifying the signature with the public key. - How the Diffie-Hellman key exchange algorithm securely exchanges cryptographic keys over a public channel and was an early example of public key exchange implemented in cryptography.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    of 17

    Muhammad Hammad

    Digital Signatures
    Outline
    ● What is Digital Signature?
    ● Purpose
    ● How does Digital Signature work?
    ● Digital Signature Process
    ● DH Key Exchange Algorithm
    What is Digital Signature?
    ● Digital Signature is one of the core building blocks of
    Cryptocurrency
    ● It involves the use of mathematical algorithm to sign and
    validate the authenticity of a document, file or software
    instead of pen and paper
    ● A digital signature is used to make sure that the file(s) sent
    digitally belongs to a designated source and reaches the
    intended receiver in its original format without any
    tampering
    What we want from Digital
    Signatures?

    Only you can sign, but anyone can verify

    Signature is tied to a particular document


    can't be cut-and-pasted to another document
    How does Digital Signatures work?
    ● The sender generates a private key and public key
    ● They sign the message with the signature and send their
    public key, the signature and the message to the network
    ● The node or receiver then checks using the verification
    algorithm that the message has been signed by the sender,
    which can only be done by the holder of the private key to
    the public key that is sent
    Digital Signature Process
    1. Generate Keys
    ○ (sk, pk) := generateKeys(key_size)
    i. sk = Secret Signing Key
    ii. pk = Public Verification Key
    2. Create Signature
    ○ sig := sign(sk, message)
    3. Verify Signature
    ○ isValid := verify(pk, message, sig)
    Public and Private Keys
    3048 0241 00C9 18FA CF8D EB2D EFD5 FD37 89B9 E069
    EA97 FC20 5E35 F577 EE31 C4FB C6E4 4811 7D86 BC8F
    BAFA 362F 922B F01B 2F40 C744 2654 C0DD 2881 D673
    CA2B 4003 C266 E2CD CB02 0301 0001 F684 B7F0

    ● Very long randomized numbers


    ● Both keys have mathematical relation, i.e. a private key is a
    single unsigned 256 bit integer and a public key is a
    number that corresponds to private key
    ● Whatever is encrypted with a Public Key may only be
    decrypted by its corresponding Private Key and vice versa
    Public Key as Identity
    ● Public Key is a unique string which can only be created
    once by a person
    ● It means that a public key can be used as an identity just
    like CNIC
    ● The author of public key also holds the secret (private) key
    so they can claim the ownership of the public key and use
    it as their identity
    ● If anybody tries to use someone else’s public key as their
    own identity, they will not have the secret key to back their
    claim; hence their fraud will be uncovered instantly
    Signature
    ● Uses Elliptic Curve Digital Signature Algorithm (ECDSA)
    to create an unforgeable signature
    ● ECDSA is the algorithm used by Bitcoin to make sure
    every Bitcoin belongs to and can be spent by its rightful
    owner
    ● Signature interlaces the message with private key in such
    way that both are inseparable
    ○ This ensures that a specific signature is for a specific
    message only
    Diffie-Hellman Key Exchange
    Algorithm
    ● Diffie–Hellman key exchange is a method of securely
    exchanging cryptographic keys over a public channel
    ● Presented in 1977, DH is one of the earliest practical
    examples of public key exchange implemented within the
    field of cryptography
    ● Authors won the Turing Award (2015) for this algorithm,
    which was first ever for anyone from Cryptography field
    Reference Book
    Bitcoin and Cryptocurrency Technologies
    Authors: Arvind Narayanan, Joseph Bonneau,
    Edward Felten, Andrew Miller, Steven Goldfeder

    Publisher: Princeton University Press

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