Abstract: Several applications use the Maxim SHA iButton® tokens for eCash, vending, fare collection, and user authentication. They require the use of secrets to recognize authentic tokens and to secure data and monetary values against tampering. The security of an entire cryptographic system rests with its ability to properly generate and protect its secrets and challenges. This application note describes methods to generate world-class cryptographic secrets and challenges. It also describes the devices that can hold those values where they are safe from attack, and describes schemes where secrets never leave the protected silicon environment at any time and are never subject to compromise. Maxim > App Notes > 1-Wire Devices iButton Security and Authentication Keywords: SHA iButton, SHA-1, secret, MAC, challenge, authentication, ecash, entropy, random numbers, cryptography, digital signature Mar 08, 2002 APPLICATION NOTE 152 SHA iButton Secrets and Challenges Abstract:Several applications use the Maxim SHA iButton tokens for eCash, vending, fare collection, and user authentication. They require the use of secrets to recognize authentic tokens and to secure data and monetary values against tampering. The security of an entire cryptographic system rests with its ability to properly generate and protect its secrets and challenges. This application note describes methods to generate world-class cryptographic secrets and challenges. It also describes the devices that can ……