Software security

Vandalism: Disturbing correct system operation.

Denial of Service: Disrupting legitimate system use.

When we talk about the methods of attacks, it is categorized as eavesdropping, masquerading, message tampering, replaying, and flooding. Therefore to avoid these attacks and build Secure Softwares, we need to be aware of the remedies available for them;

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  Eavesdropping: Obtaining message copies without authority.
  
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  Masquerading (Spoofing): Using the identity of another person without authority.
  
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  Message tampering: Intercepting and altering messages.
  
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  Replaying: Storing messages and sending them later.
  
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  Flooding: Sending too many messages
  

What is Secure Software Engineering?
“Reliable software does what it is supposed to do. Secure software does that and nothing else” (Ivan Arce)
Cryptography
Security of data at rest and data at transport is one of the basic security requirements to consider when developing software. Cryptography is the art/science of Secret writing. The goal is to keep information from those who aren’t supposed to see it by “scrambling” the original data. We use a well-known algorithm to scramble data. The cryptographic algorithms have two inputs as data & key. The key is known only to authorized users. Encryptions and Hashing are two main parts of cryptography. Encryption is a two-way function; what is encrypted can be decrypted with the proper key. That means when we encrypt (scramble) data using an encryption algorithm and a key, we can again decrypt(unscramble) data using the proper key. Hashing is a one-way function that scrambles plain text to produce a unique message digest or hash code. Therefore when we use hashing algorithms to hash(scramble) the data, it is not reversible.