How can one ensure that the transaction message will not be tampered with before it is passed from one node to the next?

To ensure that a transaction message is not tampered with before it is passed from one node to the next, you can use cryptographic techniques such as digital signatures. A digital signature is a mathematical scheme that verifies the authenticity and integrity of a message. It involves the use of a private key to sign the message and a public key to verify the signature. When a node receives a transaction message, it can use the sender's public key to verify the digital signature and ensure that the message has not been altered. Additionally, you can use secure communication protocols such as Transport Layer Security (TLS) or Secure Socket Layer (SSL) to encrypt the transaction message during transmission. This ensures that even if the message is intercepted, it cannot be read or modified by unauthorized parties. By combining digital signatures and secure communication protocols, you can significantly reduce the risk of tampering with transaction messages in a network.