1.
CRC VERSE CHECKSUM VERIFICATION
FOR USB FLASH DRIVES

2.
Is Checksum or CRC better for checking
data written to USB flash drives?

3.
SHORT ANSWER
CYCLICAL
REDUNDANCY
CHECK OR CRC
Best method for checking
data written to a USB flash
drive

4.
MANY BELIEVE
CHECKSUM Best method to verify data
written to a flash drive

5.
CRC IS BEST
Easier to understand how the
verification works
Easier to implement

6.
There are flaws in checksum verification and
therefore not suitable for verification of data
written to a flash drive

7.
WHAT IS THE DIFFERENCE BETWEEN
CHECKSUM AND CRC VERIFICATION?

8.
CHECKSUM CRC
Uses addition in its math
calculations to check whether all
data was written correctly
CRC uses long division in its
math calculations to check
whether all data was written
correctly

9.
I am talking about binary long division, not the
school-yard long division

10.
CHECKSUM
Calculate the total bits in a packet of data and
include that total checksum amount when the data
is sent over communication lines
The receiver will then look at
the packet, read the
checksum value and then
perform the same
calculation to make sure
everything adds up
If the calculation on the
receiver’s end matches the
value passed in the packet, all
is good

11.
The problem is a high probability that somewhere
between the sender and receiver the bits of data are
changed, corrupted or swapped yet still turn a
correct checksum value after calculation on the
receiving end

12.
CRC
Cyclical Redundancy Checking is about as
straight forward as addition but using long
division
The advantage with this approach is looking throughout the entire
packet to verify if all the information arrived correctly
As with traditional long division, binary division works through the
dividend number from the divisor number

13.
Cyclical Redundancy Check
Calculations are long division calculations
for a packet of information but have just a
slight bit of tweaking
TO START THE CALCULATION
Divisor number is set or “given.”
Add in zeros that are one less than the divisor number

14.
FOR EXAMPLE
If the divisor number
is 5 digits long, then
you would add four
zeros at the end of
the packet
Calculation would then start
for binary long division

15.
Now if the calculation swaps the remainder number with the four zeros
mentioned above (when the calculation first started), then when the long
division is ran again, there is no remainder (remainder is zero)
Using this method means all bits in a packet are
examined during the binary long division process
after the data packet is received

16.
Study the two charts below, then it will make sense

17.
When it comes to the reason for verification
methods to be employed for data transmission
it is typically done because of “noise” on the
transmission lines

18.
Poor design of the electrical part
Noise on a transmission line can
be encountered for many reasons
Not grounded properly
Poor quality materials used in the
device
Source: Thank you Nexcopy Inc. engineers for taking a
technical topic and presenting in a non-technical way

19.
By using dependable verification methods, the
receiver can, more reliably, determine if all the data
was sent and received correctly

20.
https://www.getusb.info/question-crc-verse-
checksum-verification-for-usb-flash-drives/
MORE INFORMATION