Public Key Cryptography Flashcards
What are the two main types?
RSA & DSA
How does it work on the most basic level?
The sender encrypts the message using the receiver’s public key.
The receiver then uses their private key to decrypt the messsage
What does Diffie - Hellman allow us to create?
A shared secret between two parties
How does Diffie - Hellman work?
- Two people have a common thing and a secret thing
- They mix their common thing and secret thing
- They share what is created with each other
- They use the other person’s thing they created and their secret thing and mix them.
- They both end up with the same thing at the end, thus creating a shared secret.
What must we be able to do in public key cryptography?
- Encrypt using the public key
- Not be able to guess the private key given the public key
What is a modular power function an example of?
A one way function
What is the formula for a modular power?
a^x mod N
What must the inverse of a modular power be able to satisfy?
The inverse, y, has to satisfy:
(a^x mod N) ^ y mod N = a
What is the formula for RSA encryption?
C = M^e mod N
Where M is the message, C is the encrypted message, and e & N are the public key
What is the formula for RSA decryption?
M = C^d mod N
Where M is the message, C is the encrypted message and d is the private key
What is a network certificate?
A public key and user identity
How is a network certificate sealed?
With a digest and signed by a ‘trusted authority’
How can certificates be chained together?
They are signed and sealed by the last in the chain and appended to the list
People higher up in the chain certify the authenticity of the public keys of those below them
