Detect Corruption with a Checksum

---

***

Welcome! I post videos that help you learn to program and become a more confident software developer. I cover beginner-to-advanced systems topics ranging from network programming, threads, processes, operating systems, embedded systems and others. My goal is to help you get under-the-hood and better understand how computers work and how you can use them to become stronger students and more capable professional developers.

About me: I'm a computer scientist, electrical engineer, researcher, and teacher. I specialize in embedded systems, mobile computing, sensor networks, and the Internet of Things. I teach systems and networking courses at Clemson University, where I also lead the PERSIST research lab.

More about me and what I do:

To Support the Channel:
+ like, subscribe, spread the word

[fsim]

You might want to cover CRC as well. CRC & checksums are heavily used in serial transfer protocols like XMODEM and ZMODEM.

[Hauketal]

The function printing a buffer should be protected against control characters. Otherwise the state of your terminal may be corrupted too.

[anon_y_mousse]

I would like to see you do a video on CRC's. Explain how they came up with the table they use mathematically. I think you could make it more approachable for newbies and would definitely make for another video to recommend.

[rustycherkas]

"You just begin. You do the math. You solve one problem and you solve the next one and then the next. And if you solve enough problems, you get to come home.”
---Mark Watney...
Like he was talking to all who attempt to write software...😁

[cleightthejw]

@Jacob

Hey, is there any reasonable thing you could do to help the volume of your audio? I'm only asking because the audio isn't horrible but it could be 'louder' (my speakers are already maxed). And there are other channels I watch where those guys are much louder on my side but I definitely didnt' change anything.

Thank you :)

[SlideRSB]

I loved The Martian. One of my favorite sci-fi novels.

[Mnogojazyk]

Dr. Sorber, I appreciate what you’ve shown us, but I’m unclear about how a checksum is used in message transmission, file storage, etc. Would you consider a demonstration of that, please?

Showing both ends of the process would be helpful, i.e., preparing the transmission and parsing the transmission upon receipt. Is the checksum appended or prefixed to the message and the entire packet sent? Or is the checksum sent in a separate transmission to mitigate against corruption, for instance?

Many thanks for your kind consideration.

[Marco-yjgg]

Too bad it doesn't work on politicians 😁

[jacko]

i think a good follow up would be combining error correction algorithms, which really are only applicable to 4 bit, 16 bit, 64 bit based blocks of data (because ecc uses 2d mapped bit arrays). but often this is used in conjunction with an acceptable error detection algorithm like crc64 and in hardware... but of course can be done in software as well. most computers today contain such hardware, like networking cards, motherboards, memory... ect. the idea is pretty simple mathematically, but demonstrates why sometimes hardware is really superior to software for certain applications... enter fpg and custom chips. i helped integrated a dedup driver for a popular file system and checksums was vital for detecting corrupted/duplicated data. i think another follow up would be how checksums can fail for detecting duplicated data if you apply encryption/compression. also checksums are the basis for maps/hashes as well if implemented correctly... actually detection and more all share a lot of commonality related to checksums as they all effectively randomize a bit stream. compression and encryption probably being the most fascinating.

[Or.BenHaim]

Isn't the case change when it bit 6? when you add the to byte 32 or subtract 32

[forben]

Can you do a video about "auto&&" and forwarding?

[toastyPredicament]

>had Bluetooth on
>Backup incomplete.

[ramakrishna]

Hi Jacob
I have been following you from month
Today I come across one questions in my interview
He asked me why pointers are not used in embedded C
I don't have points to say or to explain
Can you pls explain why pointers are useful and their disadvantages in Embedded C...

[herrdingenz]

nice explanation .. but you should do a follow-up vid about CRC/MD5 etc and how to implement those for security measures..
and since you were taling about sending data around.... why don't you write a networking lib (just some basic client/server communication thing) from scratch?
first in C .. you may use libcurl^^
and then the whole thing asynchronously in C++
just to show us how to do it ;)

[tk_real]

Aren't overflows undefined behavior?

[jeanchristophemahalomba]

I really like all of the tutorials from this channel, however i have a hard time to understand what the speaker says because it's a bit fast, it's kind from him if he speaks a bit slowly.🙂

[_b]

But how do I know that the checksum isn't corrupted 🤨