Signatures

• The way for smart contracts to verify information
• Assumption: The owner of the private key is the owner of the account
• Sign data using private key
• Unforgeable signature on an important letter

Signing and Verifying Messages in Ethereum

• Cryptographic signatures are a powerful primitive in Ethereum.
• Signatures are used to authorize transactions
• Signatures can be used to prove to a smart contract that a certain account approved a certain message.

Cheque Cashing