The preserving secrecy of sensitive data becomes very important in today digital communication. Steganography is the discipline of exchanging top secret information by embedding it into a multimedia carrier and Cryptography is the art of protecting information by transforming it into an undetectable form. The ultimate aim, here is to hide the very existence of the embedded information within seemingly innocuous carriers and transmit in such a way that the existence of information is undetectable. In this book, proposed method extracts by combining the features of cryptography and steganography. Cryptography using Modified ASCII Conversion & Mathematical Function involves converting the secret message into unprintable form of same size as original message in any cases. Steganography is then applied using multilevel 2-D DWT to embed this encrypted data into a cover media using High Frequency Coefficients of each Dimension at all levels of 2-D Haar DWT and hides its existence. This book provides all three aspects of data hiding such as capacity, security and robustness.