Implementation and Evaluation of a Dilithium-Based Post-Quantum Blockchain Prototype

The digital world relies on a system of locks and keys to keep our money, votes, and secrets safe. For decades, these locks were built on mathematical puzzles that were easy for humans to solve but nearly impossible for even the most powerful computers to crack. However, scientists have long known that a new kind of computer, one that uses the strange rules of quantum physics, could eventually break these locks in seconds. To prepare for this future, researchers are designing new locks based on different mathematical challenges that even quantum computers cannot solve. This process is called post-quantum cryptography. But simply swapping out the lock is not enough. A lock is only as good as the door it sits in, the hinges that hold it, and the people who decide when to open it. If the door frame is weak or the people are confused, the strongest lock in the world will not keep anyone safe.

A team of researchers at Misr University for Science and Technology decided to test this idea by building a working model of a digital ledger, a system often called a blockchain, which is used to record votes and transactions. They started with a prototype that used an early version of a new quantum-resistant lock and then swapped it for the officially standardized version. Their goal was not just to see if the new lock worked, but to watch how the entire system behaved when the change was made. They wanted to see if the rest of the machine—the parts that check identities, count votes, and store data—could handle the transition without breaking. What they found was that the new lock performed almost exactly as well as the old one, but the real problems were hiding in the corners of the software, in how the data was written down, and in how the different parts of the system talked to each other.

The researchers began by measuring the raw speed of the new lock, known as ML-DSA-44, against the older version they had been using. They ran thousands of tests to see how fast the system could sign a message and verify that the signature was genuine. The results showed that the new lock was not a dramatic improvement or a disaster; it was slightly slower, by about five to eight percent, but the difference was small enough that it would not slow down a real-world system. This was a relief, as it meant that the core cryptographic change was manageable. However, the team quickly realized that the speed of the lock was the least interesting part of the story. The more significant findings came from watching how the system handled the messages that passed through the lock.

In their model, the system was designed to finalize a decision, such as approving a block of votes, once a certain amount of trust was gathered from a group of validators. The researchers set up a scenario where eighty percent of the trusted validators agreed to approve a block that was actually broken and invalid. Because the system was designed to trust the signatures, it accepted the approval and finalized the bad block. This happened in every single one of the twenty thousand tests they ran. The signatures were mathematically perfect, proving that the validators had indeed sent the message, but the system failed to check if the message itself made sense. It was like a security guard who checks a visitor's ID card perfectly but fails to notice that the visitor is trying to enter a room they have no business being in. The lock worked, but the rule for opening the door was flawed.

The team also discovered a subtle but dangerous error in how the system checked who was sending a message. In one part of the old code, the system would ask the person sending a message, "Who are you?" and then use that answer to find the correct key to verify the signature. The system never checked if the name the person gave actually matched the name written inside the sealed message they sent. In a controlled test, the researchers sent twenty thousand messages where the sender claimed to be one person but the message was signed as if it came from another. The old system accepted all of them. It was only when the researchers added a simple check to compare the two names that the system started rejecting the mismatched messages. This showed that a system can be mathematically secure but still vulnerable if it trusts the wrong information to make its decisions.

Another major discovery involved how the data was stored. The researchers compared three different ways of writing down the digital records. One method used a common text format that turned binary data into long strings of letters and numbers, making the files much larger. Another method used a more efficient format but kept the same long strings. The third method used the efficient format but stored the data as raw bytes, the way a computer naturally sees them. The results were striking: switching to the raw byte format reduced the size of the records by nearly half compared to the text-heavy version. This meant that a system using the new method would need significantly less storage space and could move data faster, not because the lock was better, but because the way the data was packaged was smarter.

Finally, the team tested how the system behaved when the different parts of the network were running on separate computer processes, simulating a real distributed network. They introduced small delays to mimic the time it takes for a message to travel across a network. In one specific test, a message arrived just a fraction of a second after the system had already made its decision. The system correctly marked the message as late, but it still counted it toward the final result. This created a race condition where the outcome could change depending on the exact timing of the network. The researchers fixed this logic and re-ran the tests, confirming that the system would now correctly ignore late messages. This highlighted that even if the cryptography is perfect, the timing of when a system stops listening can be just as important as the security of the messages it hears.

The study concluded that moving to a quantum-resistant future is not just about swapping out a mathematical algorithm. It is a complex journey that requires checking every layer of the system, from the way data is written to the rules that govern how decisions are made. The new lock performed well, but the researchers found that the real risks were in the application logic, the identity checks, and the coordination between different parts of the system. For this prototype, the success of the migration depended just as much on fixing these surrounding issues as it did on the performance of the new signature scheme. The work serves as a reminder that in the digital world, a strong lock is only one part of a secure door, and the rest of the frame must be just as strong.