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Libra Message Signer and Verifier (jlibra extension)

Implements a message signing and verification mechanism using Libra accounts (ie. associated key pairs).
Can be used to check if a message was signed by a certain Libra address to prove ownage of this address.

Prerequisites

Java 8+
Maven 3+ (optional)

Use

To use signing and verifying messages out of the scope of custom Java applications, libra-java-client can be used.

Run

Run the downloaded binary (must be alpha-2+) with this command in a shell:

java -jar java-libra-client-0.0-alpha-2.jar

The application should start with a jlibra splash screen and a shell.

       _ ___ __
      (_) (_) /_  _________ _
     / / / / __ \/ ___/ __ `/    .: Connecting Libra to Java :.
    / / / / /_/ / /  / /_/ /
 __/ /_/_/_.___/_/   \__,_/
/___/

jlibra:>a c

Created account with Libra address: 9d0a6a7a4c07dfaaa4bfa950d4a1ba64721c6d0b700b81dddcf79b33bab6fad1
Public key  302a300506032b65700321003d8099c5d6752dd8f9d6c066d716d04eaeb53b4a010add4ab949cfdcefc8a91e
Private key 3051020101300506032b657004220420935623304e37057ee49a059b2ed461cc2a2d66eda2333e905fce6be92946c4888121003d8099c5d6752dd8f9d6c066d716d04eaeb53b4a010add4ab949cfdcefc8a91e

jlibra:>s m 'Hello' 0

Signed message is dedd66677267fe2582d0e4bbb14507776537fd138483ea80f3512ec36c25431ca218ed90d08283a9991b3e894e98b2eddc71ce99b19c35a8e2fb4e6c1f546704

jlibra:>v m 'Hello' dedd66677267fe2582d0e4bbb14507776537fd138483ea80f3512ec36c25431ca218ed90d08283a9991b3e894e98b2eddc71ce99b19c35a8e2fb4e6c1f546704 0

Message was signed by provided public key.

jlibra:>v m 'hello' dedd66677267fe2582d0e4bbb14507776537fd138483ea80f3512ec36c25431ca218ed90d08283a9991b3e894e98b2eddc71ce99b19c35a8e2fb4e6c1f546704 0

Message was NOT signed by provided public key.

Real Life Use Case

Message Signing and Verification Use Case

Process Flow for IOU Use Case

Alice sends Bob her address (0xALICE) and her public key (0xPUBKEY).
- Optional: Bob can let Alice send a transaction, check the address and then retrieve the public key from the events.
Alice should sign a message sent by Bob to her (which includes a Nounce or timestamp to prevent replay attacks).
Bob can verify that Alice signed the message by verifying the signed message against the public key.
Bob knows that Alice controls address 0xALICE and can safely transfer money to this address.
Optional: The message could be a contract, by signing the message Alice accepts the contract.

As a result, Alice signed the contractual agreement and gets the money transferred to the address which signed the message.
There is no possibility of fraud in the process without necessity of a trusted 3rd party.