US Patent 11784820 Systems and methods for cryptographic authentication of contactless cards

Example embodiments of systems and methods for data transmission in a contactless card are provided. The contactless card may include a processor, and a memory. The memory may contain a first applet, a second applet, and a plurality of keys. The first applet and the second applet may be stored within a shared security domain. The second applet may be configured to communicate with the first applet to perform one or more cryptographic services. The second applet may be configured to transmit one or more requests to the first applet to encode one or more payload strings based on the plurality of keys to perform the one or more cryptographic services. The first applet may be configured to perform the one or more cryptographic services on behalf of the second applet based on the one or more requests.