This document presents a methodology for a robust keyword-based document retrieval system utilizing advanced encryption. Key aspects of the methodology include:
1) Performing stop word removal and term frequency analysis to create feature vectors for documents.
2) Assigning unique numbers to terms to create a dictionary and document codes for identification and comparison.
3) Using advanced encryption techniques like substitution and mixing on the document codes.
4) Comparing the codes of user queries to document codes to find and rank the most relevant documents.
The methodology is tested on real and artificial datasets, showing improved accuracy, precision, and recall over previous methods according to experimental results.