Both Arrays.equals() and MessageDigest.isEqual() are used to compare the equality of two arrays. They can be interchangeably in many cases. However, they do have some differences which lead to different use cases in real applications.One difference is that the arrays passed to MessageDigest.isEqual() cannot be null while it's ok for Arrays.equals().The one major difference between these two methods is that Arrays.equals() is not time-constant while MessageDigest.isEqual() is time-constant. This means that when comparing two arrays, the arrays are compared byte by byte, Arrays.equals() will ret...