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Cryptographic hash

This is an interactive simulation of a cryptographic hash. Hashing consists of processing messages of arbitrary length to a unique hash value of fixed length such that any change in the message results in a large change in the hash value.

This result is valuable. You can verify that a message hasn’t been tampered with by running the message through the hash algorithm and ensuring that the hash value hasn’t changed from that supplied with the message. Even a tiny change in the message will result in a large and obvious change in the hash. In that case, you know that the message has been altered.

The algorithm used here, MD2, was introduced by Ronald Rivest in 1989. It has been replaced in use by others, such as SHA-256, but MD2 is simple and useful for learning about hashes.

Link to notes on the basic math involved and a listing of the hash function. Use your browser's Back button to return here.

After you enter or edit a message, click the Hash button and see the result. The hash value, an integer, is displayed in the hexidecimal format.

Then click the Copy button. Then make a trivial change in the message, then hash again and compare with the copy to see how the hash result has changed.

Enter or edit message, then Hash

Copies of previous message and hash for comparison

The Reactor Lab provides interactive chemical reactor simulations for active learning. The web site is Web Labs and desktop versions of ReactorLab and SimzLab, which includes PureWaterLab, are available. The lab is provided free of charge and code is open source and available at our GitHub site. The code is structured to allow fast construction of new simulations of reactors and other systems. The author of Reactor Lab is Richard K. Herz, emeritus professor of chemical engineering at the University of California, San Diego, UCSD, in the Department of NanoEngineering. Please let us know if you use the Lab or the code. Thanks!