Encrypted Shift Right and Shift Left Circuits

[NMCarv]

Problem

We needed to add dynamic shift operators (both left and right) for our garbled integers (both GarbledUint and GarbledInt) as part of our circuit SDK, so we can implement this as a circuit itself on revm.

Implementation

1. Bit–Order Reversal:

   • Modified the shift operators so that the input is reversed (converting LSB–first to MSB–first), the circuit is executed, and then the result is reversed back to our native order.

2. Operator Trait Integration:

   • Implemented the standard Rust operator traits (Shl, Shr, ShlAssign, and ShrAssign) for both GarbledUint and GarbledInt.
   • For GarbledInt, the operators convert the value to a GarbledUint, perform the shift, then convert back.
   • Both dynamic (with a garbled shift amount) and literal shift amounts (using usize) are supported.

3. Testing:

   • Updated and ran comprehensive tests in our tests/bitwise.rs file.
   • All tests (including left/right shifts for both unsigned and signed types) now pass.

Outcome:

This pull request fixes the shift operator implementations by reconciling the bit–ordering differences between our internal representation and the circuit–builder expectations, and fully integrates shift operators for both garbled unsigned and signed integers.

[10d9e]