# Image Steganography Using LSB and Hybrid Encryption Algorithms
## 2 Related Work  
The symmetric encryption technique is one of the oldest and most famous methods of maintaining data security; the secret key can be a text or several random characters. The secret key is implemented by a text message to change its content [17]. The method of encryption used in this technique is to convert each character to several alphabetic characters when the sender and recipient know the keys of all parties and then use the secret key to encrypt and decrypt the message. Blowfish is an encryption technique, more specifically a block cipher. It is frequently referred to as a cipher. Blowfish uses keys ranging from 3 to 2448 bits and has a 64-bit block size. Its creator, [PERSON], claims it is free to use, open source, and royalty free. Although Blowfish is utilized in several cipher suites and encryption methods, AES is often employed. Blowfish is secure since no cryptanalysis attempt has succeeded [18; 19]. The tool (AES) was chosen because it meets our objectives. We need a powerful encryption mechanism without the complexity of sharing multiple keys as asymmetric encryption, especially when demanding to send the parameter required for extracting the data on a secure tunnel. AES is a symmetric block encryption that uses a 128-bit encryption key, which is very hard to break. Also, the block encryption mechanism makes it possible to predict the encryption data using their language characteristic since it replaces the same data block with different coding types and sizes each time. The AES overcomes the short key use by 3 DES and other symmetric encryption, which is technically the best choice for our proposed algorithm [20]. Text steganography principles can be applied to a standard text file by hiding the message in the header information of the file. Using it this way helps maintain the original text file and jeep it the same without any change in the content itself; on the other hand, this mechanism increases the size of the file. Another mechanism replaces bits of the text file content and changes the original text, but it is not widely used since it makes the text unreadable. Text steganography can also be applied to PDF documents or other text standards [21]. The Least Significant Bit (LSB) is implemented by replacing the least significant bit in the cover image with the bit from a secret message; the LSB method hides the binary values '10110010' in a 24-bit image. The algorithm starts by uploading the cover image and the secret message, and then an end marker represented by an array of characters is added to the secret message [22]. This is performed to allow the awareness of the recovery phase of when to stop recovering in case the secret message bit's numbers do not need the full cover image pixels to be hidden since, in this case, the recovery tool continues to extract wrong data if no ending marker is found. After that, the algorithm receives each character in the secret message using a loop. It converts it to a binary value and selects three sequence pixels from the cover image based on the index of the count parameter, which starts from zero and is incremented each time a pixel is selected. Later, the algorithm extracts the three-colour components, R, G, and B, for each pixel chosen and converts each colour component to a binary value. It masks the least bit of each colour component to zero by applying (AND with 11111110). This allows the replacement of the secret character binary bits by the least bit in each colour component, which is performed later by applying XOR with one bit from the selected character bits. It is worth mentioning that the least significant bit (LSB) algorithm has been improved using the selected least considerable bit (SLSB); these techniques proposed to enhance the performance of the LSB method by hiding information only in one of the three colours at each pixel of the cover image to reduce the chance of the confidential data being detected [23; 24].