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Adding video to channels (Internet) - requested by ant.

This is more like diffie-hellman key exchange. This is not how web browsers do it. Web browsers use public key cryptography to exchange a shared secret. The public key (in the SSL certificate) is used to encrypt the shared secret. The private key (on the web server) is used to decrypt it. The shared secret is then used to encrypt/decrypt (symmetric) the remainder of the session.

Somewhere around the 3:00 mark, my definition of easily explained starts to differ...

2:56 "...it has this important property that when raised to different exponents, the solution distributes uniformly around the clock...AND the solution is never 0", he should have said.

Another mistake at 3:08: "...so if we raise 3 to any exponent x, the solution is equally likely to be any integer between zero and seventeenone and sixteen..."

I was following that up until the 4:36 mark where the numbers 16^54 magically transform into the numbers 3^(24*54) without explanation. According to my calculator 16^54 is NOT equal to 3^(24*54). Could someone please explain?

It wasn't clearly explained or animated.

Below are some of the powers of 3. Then I subtracted 17 from that number repeatedly (same as subtracting a multiple of 17) until the result was lower than 17. This result (in bold)is the final answer we're looking for. Notice that in the first 16 results, all the numbers from 1-16 are there with no repetitions. If you continue to higher powers, this exact pattern of results repeats forever (note that the three results from 3^17, 3^18 and 3^19 are the same as 3^1, 3^2 and 3^3). This relationship is the definition of "primitive root". So 3 is a primitive root of 17. After that, I think the video got a bit easier.

3^1=3 3-(0*17)=3
3^2=9 9-(0*17)=9
3^3=27 27-17=10
3^4=81 81-(4*17)=13
3^5=243 243-(14*17)=5
3^6=729 729-(42*17)=15
3^7=2187 2187-(128*17)=11
3^8=6561 6561-(385*17)=16
3^9=19683 19683-(1157*17)=14
3^10=59049 59049-(3473*17)=8
3^11=177147 177147-(10420*17)=7
3^12=531441 531441-(31261*17)=4
3^13=1594323 1594323-(93783*17)=12
3^14=4782969 4782969-(281351*17)=2
3^15=14348907 14348907-(844053*17)=6
3^16=43046721 43046721-(2532160*17)=1

3^17=129140163 129140163-(7596480*17)=3
3^18=387420489 387420489-(22789440*17)=9
3^19=1162261467 1162261467-(68368321*17)=10
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>> ^raverman:

Somewhere around the 3:00 mark, my definition of easily explained starts to differ...

Yep. According to the animation, Alice would need Bob's private number, which she doesn't have because it was never made public. I've already found 2 mistakes in this video and @schlub says it doesn't even apply to browsers anyway. So maybe this is another mistake.>> ^Arg:

I was following that up until the 4:36 mark where the numbers 16^54 magically transform into the numbers 3^(24 54) without explanation. According to my calculator 16^54 is NOT equal to 3^(24 54). Could someone please explain?

Confirmed, it's yet another a mistake in the video.

16^54 mod 17=1
AND
15^24 mod 17=1

It happens that 3^(24*54) mod 17 is also 1, but this particular calculation is never made on either end. Very sloppy explanation.>> ^Arg:

I was following that up until the 4:36 mark where the numbers 16^54 magically transform into the numbers 3^(24 54) without explanation. According to my calculator 16^54 is NOT equal to 3^(24 54). Could someone please explain?

Anyone else notice that when he is explaining modulus using the clock, that the audio he says 42, but written in the video is 46 ?

Combined with all the other mistakes, this guy should really fix his video...

I like the color example, but usually when you mix 3 colors of paint you just end up with brown.

Thanks. I think I see what he was trying to show now. I think he was attempting to explain *why*

16^54 mod 17 = 15^24 mod 17

but he left out some steps and the whole thing became confusing.


I think it works like this.

Alice performs the calculation

16^54 mod 17

however, we know that the 16 came from Bob's calculation 3^24 mod 17 = 16. So if we substitute for 16 in Alice's equation we get

(3^24 mod 17)^54 mod 17
= 3^(24 * 54) mod 17


If we make a similar substitution in Bob's equation

15^24 mod 17
= (3^54 mod 17)^24 mod 17
= 3^(54 * 24) mod 17


So, this explains why both Bob and Alice get the same result when they calculate the shared secret number but, as you say, this is not the way the calculations are actually performed by either party.
>> ^messenger:

Confirmed, it's yet another a mistake in the video.
16^54 mod 17=1
AND
15^24 mod 17=1
It happens that 3^(24 54) mod 17 is also 1, but this particular calculation is never made on either end. Very sloppy explanation.>> ^Arg:
I was following that up until the 4:36 mark where the numbers 16^54 magically transform into the numbers 3^(24 54) without explanation. According to my calculator 16^54 is NOT equal to 3^(24 54). Could someone please explain?

Nice catch. Yet another mistake. I have a feeling the narrator is a hired voice actor and doesn't understand a word he's saying, and nobody in the recording studio that day did either, and nobody reviewed the script/the final cut afterwards.

You only get brownish colours if your mix includes all three primary colours.>> ^spawnflagger:

Anyone else notice that when he is explaining modulus using the clock, that the audio he says 42, but written in the video is 46 ?
Combined with all the other mistakes, this guy should really fix his video...
I like the color example, but usually when you mix 3 colors of paint you just end up with brown.

Eah, i had problems with the colours.

I'm glad everyone chimed in here.

I was one of the first to see this video after it was posted.
My initial thought was that his description didn't ad up and he lost me as he kept leaving steps out. I also didn't think this matched correctly with browsers. I also wasn't matching the colour example with the numbers.

I wanted to comment but then I remembered my mom's warning, "It's better to let people think you don't know anything than to open your mouth and remove all doubt."

So I heeded the warning and said nothing - I guess I should have spoken up

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