Explaining Fully Homomorphic Encryption to My mom

Explaining Fully Homomorphic Encryption to my Mom

tl;dr

• Traditional encryption* = Baking bread by reading & following the recipe
• Homomorphic encryption* = Baking bread without ever seeing the recipe

Traditional Encryption

• Mom writes her secret bread recipe
• She locks it (encrypts it)
• She sends it to me (no one can steal it along the way)
• I unlock it (decrypt) and read it
• I follow the instructions and bake bread
• I can share the unencrypted recipe with others Note that both my mom and I have a version of the key. We can both lock or unlock the recipe. Afterwards, I could theoretically share the recipe with my friends who could bake bread themselves; though whether I should is another story 🙃.*

Traditional Encryption Flow for a Secret Bread Recipe

Homomorphic Encryption

• Mom writes her secret bread recipe
• She locks it (encrypts it)
• She sends it to me (no one can steal it along the way)
• I do not unlock it
• I magically follow the instructions and bake bread
• I can share the encrypted recipe with others Note that while my mom has a key she used to lock the recipe, I have a “magic key”* that lets me follow the instructions without actually knowing what’s written inside. If I were to share the recipe with others, they’d need a version of the *“magic key” as well.

Homomorphic Encryption Flow for a Secret Bread Recipe

Reality Check

Of course, there’s no literal “magic key.” Instead, it’s a mountain of math and cryptography. I don’t fully understand the details, but I do know that it’s slow and expensive.

Right now, homomorphic encryption works for small, simple online tasks. It’ll be a while before it’s fast and efficient enough to protect all of our online data.

And just for the record: I don’t actually bake bread. Here’s what usually happens instead…