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

Anyway to find Steam keys that are revealed but not redeemed? : r

strong-named-version-hell/src/MahApps.Metro.IconPacks.NewFormat

How to Link Your Steam Account – Humble Bundle

Steam: How to activate a Game / redeem a Steam key? - Epic Bundle

PSA] Humble Bundle ran out of Steam keys for Back 4 Blood : r

CustomKart/packages/MaterialDesignThemes.2.5.1/src/net45

How to Buy a Humble Bundle and Redeem It on Steam

How to Buy a Humble Bundle and Redeem It on Steam

Does Humble Bundle give Steam keys & how to redeem them

Does Humble Bundle give Steam keys & how to redeem them

How to Buy a Humble Bundle and Redeem It on Steam

How to Buy a Humble Bundle and Redeem It on Steam

PSA] Humble Bundle ran out of Steam keys for Back 4 Blood : r

13 simple ways to redeem Steam Games automatically (I made a

Humble Bundle now tying Steam account - no Steam keys - Humble