Illustrate message authentication and digital signature mechanisms. How do they work?

(Maximum 150 words, initial post latest by Thursday). References and in-text citations must be APA compliant. Please, respond substantially to a minimum of two colleagues’ posts.
Grading Rubric – DiscussionMaximum Points
1, Meets or exceeds established assignment criteria   45
2, Demonstrates an understanding of lesson concepts 45
3, Mechanics, punctuation, sentence structure, spelling that affects clarity, APA formatting  10
Total100
Grading Rubric – DiscussionMaximum Points1, Meets or exceeds established assignment criteria452, Demonstrates an understanding of lesson concepts453, Mechanics, punctuation, sentence structure, spelling that affects clarity, APA formatting 
10Total100