Cryptography is the science of making information secure in the presence of adversaries. It provides a means of secure communication in the presence of adversaries with assumed limitless resources. Ciphers are used to encrypt data so that if intercepted by an adversary, the data is meaningless to them without decryption, which requires the secret key.
Cryptography is generally used to provide a confidentiality service. On its own, it cannot be considered a complete solution but serve as a crucial building block within a larger security system to address a security problem.
Cryptography provides various security services, such as Confidentiality, Integrity, Authentication, (Entity Authentication and Data origin authentication) and non-repudiation. Additionally, accountability is also required in various security systems.
Before discussing cryptography further, there are some mathematical terms and concepts that need to be explained first in order to fully understand the material...