Abstract. Ciphire Mail is cryptographic software that provides email encryption and digital signatures. The Ciphire Mail client resides on the user's computer between the email client and the email server, intercepting, encrypting, decrypting, signing, and authenticating email communication. During normal operation, all operations are performed in the background, making it very easy to use even for non-technical users. Ciphire Mail provides automated secure public-key exchange using an automated fingerprinting system. It uses cryptographic hash values to identify and validate certificates, thus enabling clients to detect malicious modification of certificates. This data is automatically circulated among clients, making it impossible to execute fraud without alerting users. The Ciphire system is a novel concept for making public-key cryptography and key exchange usable for email communication. It is the first transparent email encryption system that allows everyone to secure their ...