Cryptography is a fascinating domain and a branch at the crossroads of several sciences. Through the decades, its techniques and objectives have evolved into many different complex structures, but its core has not changed. In order to hide any data, a suitable cryptographic mechanism and an appropriate random number (key) are needed. As most of the security models need to transmit the key separately before the encryption process, key management is still a problem to be solved. A dedicated hardware or software for random number generation solve this problem with appropriate authentication to operate them by the user. Human handwritten signature is used as a traditional way of authentication in banking, business transactions, acknowledgment of goods/services received due to its acceptance in legal and social levels. This book deals with human handwritten signature biometrics in 3D for authentication and some novel random number generators for symmetric cryptography.