Tutorials:Digital Signatures

Quest: Digital Signatures

Example:

Alice wants to prove that a particular Bitcoin address belongs to her. She signs a message with the Private Key associated with the address.

• Anybody with the message, the Bitcoin address, and the digital signature can verify that the address belongs to her.
• Only the owner of the Private Key associated with the Bitcoin address can create the digital signature.
• Even the smallest change in the message spoils the signature.

Verify the Digital Signature

1. Open the Sign/Verify window under Tools in the Electrum wallet.
2. Paste the following information into the corresponding fields:

Message: message

Bitcoin Address: bc1q6fyqcyyhkn8cy76acnf385hunpfarfxr2p8jxu

Signature: H0DBXVTGOZAzmgy/c2d1NB/Kl+vijA2ISoJFWwZoGcXWCz6687a6+fsY8B2j0+T6TEjGZ+AAG/71MFobEP2LIh4=

3) Click on Verify.

Key Concepts

• Only the owner of the Private Key associated with the Bitcoin address can create the digital signature.
• Try changing anything in the original message, and the signature will no longer be valid.

Tasks

1. Verify the digital signature.
2. Make a small change in the original message and try verifying the signature again.
3. To complete this task type in the two words that appear in the failed verification message, in the space shown in the next picture. Type all lowercase letters, do not use Upercase. (And keep the space between the words).