# Quick Intro to Encryption

Like other technical disciplines, cryptography uses a lot of technical terms and notions that an unprepared user may find confusing. Fortunately you don't have to be an expert in order to use encryption; all you need is the common sense and understanding of a few basic principles.

## What is Encryption?

Encryption is the process of converting source data to an unreadable form. The necessary
element is a *key* (*password*) that is combined with the original data
(or *plaintext*) to produce the encrypted representation (or *ciphertext*).
The conversion method (or algorithm) is called *cipher*.

Of course there must exist the reverse transformation, which uses the same key to obtain the original data from the ciphertext.

## How Secure is Secure?

The obvious question is “Is it possible to recover the original data without the key?” Although it is hardly possible to tell for sure, with all the probability the answer will be “yes, it is”. There is no defense that can not be beaten by a determined attacker, and encryption is not an exception. As with other kinds of defense, this is actually the question of cost and gain. Breaking a good cipher is a hard and costly venture, and the opponent will likely prefer more traditional methods – theft, eavesdropping, and so on.

So the task of ensuring data security requires a complex approach. In most cases a proven well-researched cipher with sufficient key size will be adequate; most attention should be paid to key storage and distribution.

## Public Key Encryption

The classical encryption scheme discussed earlier is called secret-key encryption and reflects the fact that the key must remain secret, and that the opponent, who managed to obtain the key, immediately gets access to all the encrypted data.

Secret-key encryption is the cryptography workhorse. Secret key encryption algorithms are fast, reliable, and are used virtually everywhere. However in some areas the requirement of key secrecy is too limiting a factor, so open key crypto systems were developed to solve the problem of secure key distribution.

An open key consists of two interdependent parts, one for encryption, and one for decryption.
These parts are not interchangeable; in particular, the encryption part cannot be used for decryption.
According to the widely used terminology, we will call the encryption part a *public key*,
and the decryption part – a *private key*.

A simple example illustrates how public key encryption works: Alice wants to send a message to Bob.

- Bob sends her his public key.
- Alice encrypts the message with Bob's public key and sends the encrypted message back to Bob. An opponent can intercept both the public key and the encrypted message, but cannot decrypt the message without the Bob's private (decryption) key.

## Is It the Ultimate Solution?

Unfortunately, it is not. Public key encryption has its own specific and serious problems. For instance, let's make the example above a little more real-life:

- Bob sends his public key by email. On the way to Alice the email goes through several mail servers.
- Carol (the opponent) has access to one of those servers. Carol intercepts the Bob's email and substitutes it with an email containing her own public key, so Alice encrypts message with Carol's key instead of Bob's. Carol intercepts Alice's message on the way back, re-encrypts it with the real Bob's public key, and sends it to Bob.
- Alice and Bob believe their communication is secure. In reality Carol have the full access to their messages, and it is interesting to note how easily she got that access.

Public key encryption solves the problem of secure key distribution excellently, but introduces no less serious problem of key authenticity, which still has no universal solution.

## Public Key vs. Secret Key

Both secret-key and public-key crypto systems have their strong and weak points. In order to protect your data reliably you should understand how they work and choose the system best filling your needs.

Use public key encryption if

- You are sending data to many people,
- You are sending data to people you never met,
- There is no secure way to transfer the key.

Keep in mind the possibility of data interception by a “middleman” and carefully plan your data procedures.

Use the secret key encryption if

- There is a limited number of users/recipients,
- There is a safe way for key distribution (for example, if all recipients are in the same organization).

## Our Software

Our encryption software - Kryptel and Silver Key – provide reliable protection of your data with well-known and proven encryption algorithms: AES, Serpent, Twofish, Blowfish, and Triple-DES. Both the programs use secret key encryption and are targeted for use by individuals, small user groups, or large user groups within the same organization.

Kryptel is a program for secure file storage. It provides single-click encryption, encrypted backups, batch processing and more.

You will need Silver Key if you want to send files over the Internet. Silver Key creates encrypted parcels that can be decrypted without installing additional software. Like Kryptel, Silver Key provides single-click encryption and many other features such as automated batch jobs.