What is blockchain technology
blockchain
technology
Blockchain We'll start with the
definition. So, to better understand how Block chains are distributed
let's start with an analogy. Let's say I am with a group of friends and lend my
friend Pat ten dollars. Now the friends see the transaction go down and they
know that I have the correct amount of money and in addition they've
essentially endorsed the transaction and they made a record of it.
Now next week when Pat comes
back to me to ask how much money had initially lent her, we could easily go to
any of my friends that have a record of that transaction. Next let's introduce
the fact the Blockchains are immutable. To do so let's dive into the pieces
that makeup a block chain.
block chain technology explained
First, we're going to have
the transactions. So, this is going to be all the transactions that occurred
when that block was created. In addition, there's going to be a hash.
So, let's take a couple
letters for the hash, generally it's an alphanumeric sequence and is usually a
lot longer, more secure.
So, let's say where you know
right in the middle of the Block chain here and we'll pick something for the
previous hash, maybe "2a",and so now let's move on to the next
block.
And so on, and so forth we
can kind of extrapolation all of the hashes in previous sessions. So,
we'll start with the permission less Block chain.
how does blockchain technology work
blockchain
technology how does it work
Now, the next thing I want
to talk about is the idea of a permission versus a permission less Block chain.
So, we'll start with the permission less Block chain.
Now attendees are not
exactly revealed, it’s only the addresses that people have, but regardless all
the transactions are public and in addition anyone can register themselves to
be one of the nodes in the network essentially having copy of the block chain
and anytime it gets updated and new transactions are made they would get a new
block.
blockchain information
Types of block chain technology
1 . private key
2 . public key
A private key right you could Make this one is a
private key It's not a very good one lots of people have thought of the number
one before but you could you know you could pick some really long number and
it's sort of a random number and We can use that as a private key.
what is a blockchain
Now. You can see every
time. I'm adding digits here its Recomposing the public key that relates to
that private key, and that's why the stuff down Here starts changing so as the
name would imply this Private key is to be kept private only you have this private
key, and you never tell it to anyone else Okay, and just as the name implies
Public key the public key here,
you just tell
everyone this is something that you want everybody to know This is something
that there's no harm in letting everyone know There is not a way to derive from
this public key What the private key is okay?
So it's just a kind of a
public Version of this private key that does not reveal what the private key is
Okay, so I'm going to hit my little ray number generator, so I get a nice really
long private key And it's not something you know where the numbers are close
together where I typed On the keyboard it's something a little bit more random
looking and then the system has derived a public key From this so this is going
to be my private key, and I'm going to use this to do signatures So let's do
that right now, so Here's a message signature So here is a message.
blockchain wallet
blockchain my wallet
I'm going to type. You know
hello on dears. That's me and I have My private key here six five six whatever
it is my private key only I have that and here's the message that only I have
And I can hit sign and come up with a message signature here now this message
Signature I can pass to someone else I'm going to hit my little verify button
I'm going to pass this message signature to someone else to anybody else okay
now of course they don't have my private key because I keep that private nobody
else can see that but I Publicize my public key, and they know that everybody
knows that this is my public key
what is blockchain
technology
So given this message
and everybody knows my public key and given the signature that I just made You
should be able to verify this now of course if I hit verify sure enough the
screen goes green This is a valid message And I have verified that whoever
signed this message and came up with a signal Signature had access to the
private key behind this public key Okay, and if I have kept that private key
secret that must be me okay
So that's a message
signature And how you can sign something and verify it now instead of just
using this freeform text box Let's put some structure around this. I'm going to
make a transaction here instead all right.
This is similar to what we
saw before the message I'm going to say is I'm going to send twenty dollars
from this happens to be my public key to Somebody else's public key whoever
this is that I'm sending money to okay? I Of course because I'm Simon smashes.
I have my private
key. I never tell anybody the private key, but I can use this private key to
sign this message Which consists of these three things up here? And if I hit
sign I get a message signature great all right now I send this whole thing out
I send out my message and my signature to somebody else and They know that I'm
trying to send twenty dollars from my public key to this somebody else's public
key .
what is a blockchain
You'll notice this little
blue box around the from public key that suggests that You can check this
signature against this public key to see whether or not the private key behind,
this public key actually sign this message so let's hit verify sure enough it
verifies
I know that the
person in possession with the Private key behind this public key must only
binders is sending twenty dollars To some other public key, okay, now, let's
use this in the block chain
blockchain explained
Let's go back to the block chain
case where we were that we're looking at before now You'll notice a couple of different
things here all right first of all There's not names here anymore right there
are just public keys in the form and the two and you'll also notice that that I
added a signature section here, okay, so In this case this is this Public key
sending two dollars to this public key And here's a message signature that says
that it is well What happens if I change this to you know 25 dollars okay? Of
course it broke the block
But it also broke the
signature. The signature is not verified and that's why the signature is
turning red so Wow? we couldn't press the little mine button you know a miner
could take this altered block and Remind this block They're going to end up
with something where the block is signed which should eventually happen and
there we go and the signature though is still invalid because the minor has no
they don't have my Private key, they only have my public key, so they can't
come up with the right signature. Okay,
what is bitcoin
blockchain
so that's the way We can
make sure that The message this transaction here was posed By the person that
had the money and only that person not just anyone else on the Internet So
that's how public private key pair Message signing is used to protect transactions.
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