msk5293

I think you're referring to Plaid's Auth product, which is for verifying bank accounts. https://plaid.com/products/auth/

AES is only defined for 128, 192, or 256 bit keys. You'd need to switch to a different block cipher like Blowfish (up to 448 bit keys), RC2 (up to 1024 bit keys), or RC5 (up to 2048 bit keys) to have a larger keyspace.