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## sm3p0

# Function sm3p0

Source

    pub fn sm3p0(rs1: u32) -> u32

🔬This is a nightly-only experimental API. (`riscv_ext_intrinsics` #114544)
Available on target feature `zksh` and (RISC-V RV32 or RISC-V RV64) and (RISC-V RV64) only.
Expand description

Implements the P0 transformation function as used in the SM3 hash function [4, 30].

This instruction is supported for the RV32 and RV64 base architectures. It implements the P0 transform of the SM3 hash function [4, 30]. This instruction must always be implemented such that its execution latency does not depend on the data being operated on.

Source: RISC-V Cryptography Extensions Volume I: Scalar & Entropy Source Instructions

Version: v1.0.1

Section: 3.41

## §Details

`P0` transformation function as is used in the SM3 hash algorithm

This function is included in `Zksh` extension. It’s defined as:

    P0(X) = X ⊕ (X ≪ 9) ⊕ (X ≪ 17)

where `⊕` represents 32-bit xor, and `≪ k` represents rotate left by `k` bits.

In the SM3 algorithm, the `P0` transformation is used as `E ← P0(TT2)` when the compression function `CF` uses the intermediate value `TT2` to calculate the variable `E` in one iteration for subsequent processes.