SHA-256 and its more advanced counterparts are considered robust and resistant to attacks due to several key features:

• Fixed-Size Output: SHA-256 produces a hash value of 256 bits, regardless of the input size. This fixed size helps in preventing certain types of attacks, such as length extension attacks1.
• Collision Resistance: It is computationally infeasible to find two different inputs that produce the same hash output in SHA-256. This property is crucial for security because it means that each input has a unique hash, making it extremely difficult for an attacker to replace or forge data2.
• Pre-Image Resistance: Given a hash output, it is practically impossible to reverse-engineer the original input. This one-way function property ensures that even if the hash is exposed, the original data remains secure3.
• Second Pre-Image Resistance: It is also computationally infeasible to find a second input that has the same hash as a given input. This protects against substitution attacks where an attacker might try to replace a legitimate piece of data with another that has the same hash1.
• Avalanche Effect: A small change in the input data (even just one bit) will result in a completely different hash output. This characteristic is essential for security because it makes it very difficult for attackers to predict how changes in the input will affect the hash output4.
• Cryptanalytic Resistance: SHA-256 is designed to withstand various cryptographic attacks, including brute force attacks. The large hash size and the complexity of the algorithm make it resistant to current cryptanalytic techniques.

These features make SHA-256 and similar hash functions suitable for securing sensitive data, verifying data integrity, and other cryptographic applications where robustness and resistance to attacks are paramount.

https://ocw.mit.edu/courses/6-046j-design-and-analysis-of-algorithms-spring-2015/6741d65be662edac7c169c4081b3bd9a_MIT6_046JS15_lec21.pdf

What hash is more secure, SHA256, SHA512, or MD5? | IToolkit

sha 1 - Does the SHA hash function always generate a fixed length hash? - Cryptography Stack Exchange

https://medium.com/@mohaisen/cryptographic-hash-functions-a-hands-on-introduction-100c93a79f65

https://medium.com/@millennialdev/lesson-5-cryptographic-hashing-ca00fe459baf

A Deep Dive into SHA-256: Working Principles and Applications | by Madan | Medium