Many smart card components are now closed source and maintained by Apple for its different OSes. I can cite:
- CryptoTokenKit
- PC/SC API
CCID driver
Apple provides my Free Software CCID driver. The source code from Apple is available at:Version 55017 corresponds to CCID version 1.4.27 and was already present in macOS High Sierra as noted in "macOS High Sierra and smart cards status".
Tokend
Apple still provides "support" of the tokend technology even if it is deprecated since OS X Lion (2011). The source code is provided at:The version 55111 has not changed since macOS Sierra. see "macOS Sierra and smart card source code".