What is a collision in a hash function? (2 points)
• 2 inputs map to the same output
O There are few inputs, but a lot of outputs.
O 2 outputs come from the same input
O There are few outputs, but a lot of inputs.
• 2 inputs map to the same output
A collision in a hash function occurs when two different inputs produce the same output.
The correct answer is: 2 inputs map to the same output.
A collision in a hash function refers to a situation where two different input values produce the same output value. In other words, when two distinct pieces of data generate the same hash value. This can occur due to the finite number of possible hash values when compared to the potentially infinite number of input values.
To understand how collisions happen, it's important to know how a hash function works. A hash function takes an input (like a string or data) and applies a specific algorithm to generate a fixed-size output, also known as a hash value or hash code. Hash functions are commonly used in various applications, including data structures like hash tables, security protocols, and digital signatures.
Ideally, a hash function should produce unique hash values for each unique input. However, due to the limitations of its output size, it's inevitable that multiple inputs will occasionally collide and result in the same hash value. These collisions can be intentional (in the case of attacks like collision attacks) or unintentional, depending on the specific hash function and the distribution of the input data.
To prevent or minimize collisions, cryptographically-secure hash functions are designed to have a low probability of collision, even in the face of intentional attacks. These functions employ complex algorithms and mathematical properties to distribute the hash values as evenly as possible across the output space, making collisions statistically unlikely.
It's worth noting that collisions can still occur in practical scenarios. Therefore, many applications and systems handle collisions using techniques like separate chaining or open addressing in hash tables, or by adding additional complexity to the hash function to reduce the likelihood of collisions.