Which aspect does cryptography focus on?

Cryptography primarily focuses on securing messages and data, ensuring that sensitive information remains confidential and protected from unauthorized access. This includes techniques such as encryption, which masks the content of a message so that only intended recipients can read it, and digital signatures, which verify the authenticity of data. In a digital environment where information is constantly shared over networks, cryptography plays an essential role in safeguarding communications, maintaining data integrity, and verifying identities.

While improving customer service, aiding in sales strategies, and upgrading payment systems are important aspects of business operations, they do not directly pertain to the fundamental purpose of cryptography. Thus, the emphasis on securing messages and data highlights cryptography's critical function in protecting information within various online transactions and communications.