Prime Numbers & Public Key Cryptography

A simple explanation of how prime numbers are used in Public Key Cryptography from ABC1 science program Catalyst

[thomashan]

One of my friends doing cryptography said "You try to make your lock more powerful, I try to go over the fence."
I never forget what he said.

[lobelia]

incredible. and mathematicians actually came up with atm security using prime numbers back in 1978! wow!

[orgonsolo]

Have you read the book "Calculate Primes" by James McCanney? Says there is a method to directly calculate primes up in infinite numbers by adding and subtraction... Its really interesting study

[TenHanger]

like the simple explanation, but more details on what the bank's computer system is doing would be better.

[marodna]

Hemi2050 > The private keys are not exactly p1 and p2, but they are calculated from those prime numbers. Thus, if p1 or p2 are not primes, this calculation won't give confidence to the correctness of the encryption then the decryption itself.

[hsharma]

its not quite like a safe deposit box where both the bank and you can see the same secret. The public and private key are cryptographically related. You each have a set. The bank sends a message to you, and its encrypted with your public key, which means it is obligated to be unlocked by your private key. Nobody else should have your private key, not even the bank (or any server). Messages are locked using the public key and unlocked using the private key. The only time im aware that you would encrypt something with the private key is if you wanted to sign something (as everyone would be able to decrypt and see the signature using your public key, which is desirable.

[chrisvsworld]

great video! thanks. was great for my year 7 maths class.

[HardcoreDetroit]

Prime numbers in the Holy Qur'an:

Message encoded within the first chapter of the Quran appropriately named THE KEY (الفاتحة) which has 7 verses, 29 words, and 139 letters. Not only are these prime numbers but their digit sums (7=7, 2+9=11 and 1+3+9=13) are primes too, and the grand total of these sums (7+11+13 = 31) is yet another prime!!! Arranged these numbers (7, 29, 139) next to each other right-to-left and left-to-right (i.e. 139297 and 729139) and guess what? Both are primes! SubhanAllah

[olliespearing]

The largest Prime Number known at the time is now: 2 ^ 57, 885, 161 minus 1.

[gmaniiyyan]

Thank you sir for this great video explanation, I have a question, when you find time please let me know.

Question:
Why we need two large prime to get the public key, we can just use any two large number, multiply it and create a public key, why we are using prime number specifically for this?

Thanks for your time!!

[lunyteve]

I like how Australians have 5 syllables in the word "so"

[Censkyml]

my math cher sent me here, btw this zikri

[titobruni]

Why only multiplying 2 primes? Wouldn´t it be harder to find out the primes of a number composed by, lets say, 3 primes? Just a question.

[charkopolis]

perhaps it's only 1000 years if Moore's law holds for long enough

[alphabravo]

I've always wondered if there's a last prime number.

[cabeloDoPardal]

Amazing.

2:55 "just die nine"

[SnoopyDoofie]

Tip: If you discover a prime number, don't tell the world about it. Sell it to a bank or financial institution who will use it for encryption. Telling the world about it makes it useless for encryption.

[LabsResearch]

If somebody knew a method of factoring faster than what is currently know and able to break large RSA semiprimes .. what would it be worth?

[Hemi]

You don't need to use primes for p1 and p2, you can use any two large numbers.

[paulvanderveen]

Actually, 2^57885161 -1 and 2^74207281 -1 are both prime numbers greater than 2^43112609 -1.