1. SAS-ROS Cipher by: saaiqSAS Last Updated: 27/2/2025 SAS-ROS Cipher (Saaiq Abdulla Saeed's Random Object Substitution Cipher) is a method of randomly substituting a data object with another object from a fixed set of objects. It achieves this substitution using two types of randomly generated keys: the Dynamic Key (Object Key) and the Static Key (Index Key). When combined, these keys form a substitution table. This cipher serves as the core of the SAS-RCS/RBS Encryption.

The ROS Cipher was originally developed by Saaiq Abdulla Saeed (saaiqSAS) as the core of the now-deprecated SAS-STE (SAS - Secure Text Encryption) algorithm [project Github]. SAS-STE was a weak ASCII substitution encryption, and it was the first encryption algorithm created by saaiqSAS. The names 'Dynamic Key' for Object Key and 'Static Key' for Index Key were derived from this project.

Dynamic Keys are sets or arrays of randomly shuffled objects, where the objects can be of any type (e.g., characters, bytes, frequency, voltage, etc.). Static Keys are sets or arrays of randomly shuffled indexes, which are of the same length as the Dynamic Key, and are used to link the objects within the Dynamic Key during substitution.

There are two methods to perform the ROS Cipher, which are inverses of each other. Therefore, if one method is used for encryption, the other can be used for decryption, and vice versa. ROS method 1 (m1) Dynamic Key: { j, i, d, a, h, c, g, f, e, b } Static Key : { 4, 8, 2, 7, 1, 6, 0, 5, 9, 3 } Data: b 1. Locate the index of 'b' in Dynamic Key - [9] 2. Retrieve the integer in the [9] index of the Static Key - 3 3. Identify the character in the [3] index of Dynamic Key - 'a' 4. Substitute 'b' to 'a' out: a Fig.1.1 ROS method 2 (m2) Dynamic Key: { j, i, d, a, h, c, g, f, e, b } Static Key : { 4, 8, 2, 7, 1, 6, 0, 5, 9, 3 } Data: b 1. Locate the index of 'b' in Dynamic Key - [9] 2. Locate the index of '9' in Static Key - [8] 3. Identify the character in the [8] index of Dynamic Key - 'e' 4. Substitute 'b' to 'e' out: e Fig.1.2 Decrypting m1 output via m2 Dynamic Key: { j, i, d, a, h, c, g, f, e, b } Static Key : { 4, 8, 2, 7, 1, 6, 0, 5, 9, 3 } m1 Encrypted Data: a 1. Locate the index of 'a' in Dynamic Key - [3] 2. Locate the index of '3' in Static Key - [9] 3. Identify the character in the [9] index of Dynamic Key - 'b' 4. Substitute 'b' to 'e' out: b Fig.1.3 Decrypting m2 output via m1 Dynamic Key: { j, i, d, a, h, c, g, f, e, b } Static Key : { 4, 8, 2, 7, 1, 6, 0, 5, 9, 3 } m2 Encrypted Data: e 1. Locate the index of 'e' in Dynamic Key - [8] 2. Retrieve the integer in the [8] index of the Static Key - 9 3. Identify the character in the [9] index of Dynamic Key - 'b' 4. Substitute 'b' to 'a' out: b Fig.1.4