On January 15th, 2019 starting at 9:00am PT, Authorize.Net will be removing support for the below ciphers in Production (Akamai endpoints only).
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA = ECDHE-RSA-AES256-SHA
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA = ECDHE-RSA-AES128-SHA
TLS_RSA_WITH_AES_128_CBC_SHA = AES128-SHA
--api2.authorize.net - API
--secure2.authorize.net - API
--account.authorize.net - Portal
--login.authorize.net - Portal
--partner.authorize.net - Portal
Sandbox has already been updated as of 11/06/2018.
Please refer to our TLS/Cipher FAQ for additional information:https://support.authorize.net/s/article/Authorize-Net-Support-for-SSL-TLS-FAQ