Encryption algorithms are essential for protecting sensitive information and
ensuring secure communications in a variety of domains. They are used for
several important reasons:

* Confidentiality, privacy, and intellectual property protection
* Security during transmission or on storage devices
* Data integrity, general trust, and authentication

When selecting encryption algorithms, tools, or combinations, you should also
consider two things:

1. No encryption is unbreakable.
2. The strength of an encryption algorithm is usually measured by the effort required to crack it within a reasonable time frame.

In today's cryptography, the length of the *key* directly affects the security
level of cryptographic algorithms.

Note that depending on the algorithm, the term *key* refers to a different
mathematical property. For example:

* For RSA, the key is the product of two large prime numbers, also called the **modulus**.
* For AES and Elliptic Curve Cryptography (ECC), the key is only a sequence of randomly generated bytes.
** In some cases, AES keys are derived from a master key or a passphrase using a Key Derivation Function (KDF) like PBKDF2 (Password-Based Key Derivation Function 2) 

If an application uses a key that is considered short and *insecure*, the
encrypted data is exposed to attacks aimed at getting at the plaintext.

In general, it is best practice to expect a breach: that a user or organization
with malicious intent will perform cryptographic attacks on this data after
obtaining it by other means.
