Redeem Steam key to account with Steam OpenID like Humble Bundle

Humble Bundle has started requiring the user to sign in through Steam's OpenID authentication where it then redeems the Steam key on the user's account. I was unable to find any documentation on this

Insanely clever Steam credential stealing scam using fake Sign in

Email Marketing Handbook: Second Edition - IMN Inc.

Steam (service) - Wikipedia

How to Buy a Humble Bundle and Redeem It on Steam

How to Buy a Humble Bundle and Redeem It on Steam

Steam New Profile Privacy Settings [ALSO, STEAMGIFTS 0 WISHLIST

How to Redeem a Gifted Bundle or Game – Humble Bundle

Free Game Redemption Instructions – Humble Bundle

Steam Forces Humble Bundle to go Back to Giving Out Steam Keys

How to Buy a Humble Bundle and Redeem It on Steam

How to Buy a Humble Bundle and Redeem It on Steam

Steam Removing Support for OAuth

Does Humble Bundle give Steam keys & how to redeem them

How to Redeem a Gifted Bundle or Game – Humble Bundle

How to Buy a Humble Bundle and Redeem It on Steam