Encryption Basics & Quantum Computer Part -1

Recent iPhone Data encryption and controversy over Security vs Privacy debate reminded me my 2003 final project on Quantum Computing. So I just thought of writing a series of post on Security and Encryption. This is part 1

We can rely on today's encryption system because factorization is an intractable problem in Classical Computing model. When the numbers are very large, no efficient, non-quantum integer factorization algorithm is known. These are called NP Complete problem algorithm terms.

This encryption system could be broken if we use a Quantum Computer (At least in theory).

However before we get into detail how Quantum Computer can be used to break current Day Cryptography System and lets refresh the basics.

There are three associated Encryption Strategies possible in Classical Computing paradigm

Symmetric Encryption

• Same secret Key is being used to encrypt & decrypt the message.
• Anyone who knows the secret key can decrypt the message.

Asymmetric Encryption

• Two separate keys being used - one public key broadcast-ed anyone who wants to send encrypted message

• A second, private key is kept secret

• Any message (text, binary files, or documents) that are encrypted by using the public key can only be decrypted by applying the same algorithm, but by using the matching private key. Any message that is encrypted by using the private key can only be decrypted by using the matching public key. 

• To identify the origin of the message a digital certificate is used to sign the message

One of most widely used Data Encryption PGP - Pretty Good Privacy used Asymmetric Encryption Strategy to protect the data and same is used in HTTPS.

Here is how it works:

Please watch this excellent video explaining the same: