Ch 4 Encryption4.1 IntroductionCryptography is the common term given to the art and science of keeping text messages secret. The aim is not to evaluate in detail the mathematical algorithms used in the cryptographic process, but rather to provide a general overview of the process and its uses. To briefly introduce one of the fundamental elements of any network security, one must know the encryption and decryption process. A process that transforms given information (the plain text) into a seemingly meaningless form (the ciphertext) using a mathematical algorithm and some secret information (the encryption key). The decryption process revokes this transformation using a mathematical algorithm, in conjunction with a secret value (the decryption key) which reverses the effects of the encryption algorithm. An encryption algorithm and all its possible keys, plaintexts, and ciphertexts are called a cryptographic system or cryptographic system. Figure 4 illustrates the process. Cryptography has two main characteristics:1. It should be computationally impossible to derive the plaintext from the ciphertext without knowing the decryption key.2. It should be computationally impossible to derive the ciphertext from the plaintext without knowing the encryption key. Modern encryption systems are derived from one of two basic systems: symmetric key systems (sometimes called shared key) and asymmetric key systems (often called public key). ) systems. An encryption process in which the sender and recipient share a unique and common key used to encrypt and decrypt the message, is then called a symmetric key system. Symmetric key systems are simpler and faster, but their main disadvantage is in the middle of the paper stage......, and compares to D-Shuffle sorting in the next stage and the results are now compared and discussed below The new sorting method proposed for secure message transmission compared by bubble sort technique is achieved 97.05%. The improvement reflects the efficiency and simplicity of direct substitution of the sorting technique. Figure 6. Comparison of bubble sort based encryption with D-Shuffle sort 4.6 Conclusions In the field of cryptography, a new idea has been incorporated into the sorting technique to encrypt the text message. for secure communication. This new study involved a fast and secure direct substitution message transmission system. Fast and secure encryption is achieved through sorting algorithms that could increase the performance of the transmission mechanism. This algorithm is based on the substitution techniques of classical encryption.