Please note that zkApp programmability is not yet available on Mina Mainnet, but zkApps can now be deployed to Berkeley Testnet.
Gadgets
Gadgets are amalgamations of the lowest level gates in the proof system (addition, multiplication) into more sophisticated boolean operations (XOR, NOT). This simplifies the process of creating new cryptographic primitives.
In this case, the gadgets form the basis of ECDSA signature verification. These gadgets allow the community to implement other crypto algorithms, such as SHA.
Gadgets.rangeCheck64(): A provable method for efficient 64-bit range checks using lookup tables. (0.14.0, #1181) Gadgets.rotate(): A provable method to support bitwise rotation for native field elements. (0.14.0, #1182) Gadgets.xor(): A provable method to support bitwise XOR operations for native field elements. (0.14.0, #1177)