STid 8870 (2K AES Smart Card): What It Is & How to Reorder

The STid 8870 is STid's 2K-memory AES-secured 13.56 MHz smart card, referenced in STid's US catalogue among its Architect-compatible credentials. It operates over ISO/IEC 14443 Type A and is designed to be encoded with AES-128 keys through the STid SECard kit, then read by STid Architect readers.

"8870" is a card SKU, not a security level — the security is defined by how it is keyed. On its own, an 8870 is a blank AES smart card with 2K of memory. Once a site writes its private keys and application layout onto it with SECard, it becomes a working credential that authenticates by AES mutual authentication with a per-card diversified key. That is why two physically identical 8870 cards can be completely non-interchangeable between two different buildings.

"2K" refers to the card's on-chip memory — roughly two kilobytes — which is plenty for access control alone but limits how many separate applications the card can hold. STid and equivalent AES smart cards come in 2K, 4K, and 8K memory sizes, often referenced by their chip codes. Choose the size by how many applications the card must carry, not by how secure it is: all three sizes use the same AES cryptography.

You cannot buy a working "compatible" STid 8870 card because a live credential must contain your site's private AES keys, and those exist only inside your STid SECard kit. A card sold pre-encoded by a third party would either carry the wrong keys (and never open your doors) or would require someone to already possess your secret keys — which, in a correctly run STid deployment, no outside party does.

This is by design and is the whole point of STid's "create your own security keys" model, explained in full in the STid Architect & SECard guide. Security ID Systems does not sell a drop-in encoded 8870, and any supplier claiming to offer a ready-to-use "compatible" STid card for a keyed site should be treated with suspicion. The legitimate paths are blank stock encoded by your own integrator, or the open formats below.

Blank STid 8870 stock can be reordered and then encoded by whoever holds your site keys — usually your integrator, using SECard. That is the correct route for topping up credentials on an existing STid Architect system without compromising your key policy.

What Security ID Systems supplies directly is the surrounding layer many STid sites still run: 125 kHz proximity cards on legacy doors, and card-serial-number (CSN) or generic Wiegand credentials where an Architect reader is set to read a plain identifier. Those open and UID-based formats we encode as fully compatible credentials that read identically on your existing readers, so you can standardise the low-security doors while the keyed 8870 credentials stay under your own control.