proposed how to do public-key encryption, and Merkle
showed that a shared key could be sent
across an insecure channel.
What do you do? Each party, Alice and Bob,
chooses a secret value and shares a common value.
Now each derives a shared sum of the three values.
First each shares a mix of their own value with the shared value
and then each mixes their own with the mix of the other
so that now each has a mix of the three values.
The values are large prime numbers, difficult to factor.
This is known as Diffie-Hellman key exchange.
Public-key is asymmetric-key cryptography.
Both Alice and generate two keys,
one to be shared and used for encryption,
and the other to be kept private and used for decryption.
Typically, this technique is used for sharing a symmetric key
that can be used to encrypt and decrypt messages in both directions.
Pretty Good Privacy
PGP uses hashing, data compression,
symmetric-key cryptography,
and public-key cryptography.
It encrypts a message
with a symmetric key, and
uses the receiver’s public key
to encrypt the symmetric key
that it sends along
with the encrypted message.
The receiver uses his or her private key
to decrypt the symmetric key,
which decrypts the message.
Identity
Your identity should be inviolable,
and it’s not.
You should own your own name,
your birth place and birth day,
your habits and desires,
your photographs and social connections,
and you don’t.
You have your own physical being;
this is normally inviolable.
After that, it should be OK
to share your identity
with family and friends.
But it shouldn’t be OK
for a corporation to own your identity
or sell it for their own profit.
This is a matter of principle,
not of actuality.
Identity should be more sacred than biology,
and identity is mainly not how we decide group membership in our culture.
This can change.
The value of privacy increases as it becomes a tool for people
to control their own contributions to society.
Identity should be more sacred than biology, and identity is mainly not how we decide group membership in our culture. This can change. The value of privacy increases as it becomes a tool for people to control their own contributions to society.
See also in The book of science:
Readings in wikipedia: