Implement HMAC From Scratch | Dataford Interview Questions

Implement HMAC from scratch in your preferred language.

Implement hmac_sha256(key, message), treating both inputs as UTF-8 strings and returning the lowercase hexadecimal HMAC-SHA256 digest. Use a 64-byte SHA-256 block size, hash keys longer than one block, and apply the standard inner and outer padding constants.

Constraints

0 <= len(key) <= 10^5 characters
0 <= len(message) <= 10^6 characters
Inputs contain valid Unicode strings
Use SHA-256 as the underlying hash
Return exactly 64 lowercase hexadecimal characters

Function Signature

def hmac_sha256(key, message):

Your question is Implement HMAC From Scratch. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Implement HMAC from scratch in your preferred language.

Constraints

0 <= len(key) <= 10^5 characters
0 <= len(message) <= 10^6 characters
Inputs contain valid Unicode strings
Use SHA-256 as the underlying hash
Return exactly 64 lowercase hexadecimal characters

Function Signature

def hmac_sha256(key, message):

Your question is Implement HMAC From Scratch. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.