Bit Shift & Rotate

Category: Utility · Node Type ID: utility-bitshift

Shifts or rotates a byte array by a number of bits (SHL, SHR, ROL, ROR)

Overview

Treats the entire input byte array as a single contiguous big-endian bit vector of $8 \times N$ bits and shifts or circularly rotates all bits by the specified bit count: Logical Shift Left (SHL, <<), Logical Shift Right (SHR, >>), Rotate Left (ROL), or Rotate Right (ROR).

Carry bits shifted out of one byte cross seamlessly into the adjacent byte! The bit count can be configured via the Bits property or overridden dynamically at runtime by connecting an integer to the optional Bits input port. Output byte length always equals the input byte length.

When to Use

Implementing GF($2^{128}$) subkey doubling in AES-CMAC / XTS (1-bit left shift across 16 bytes with conditional polynomial XOR).
Performing multi-byte circular bit rotations (ROL / ROR) or bit-level alignment across protocol buffers.

Parameter Configuration

Parameter (ID)	Type & Default	Visibility Condition	Description & Options
Operation `operation`	`select` Default: `SHL`	Always visible	Selects the bit-level operation across the entire byte array: `SHL` (zeros shifted in from the right), `SHR` (zeros shifted in from the left), `ROL` (MSB wraps around to LSB), or `ROR` (LSB wraps around to MSB). `SHL`: SHL (Bit Shift Left <<) `SHR`: SHR (Bit Shift Right >>) `ROL`: ROL (Bit Rotate Left) `ROR`: ROR (Bit Rotate Right)
Bits `bits`	`number` Default: `1` Supports Variable Reference (`$var`: `int`)	Always visible	Number of bits to shift or rotate (integer `≥ 0`; default `1`). Ignored if the optional `Bits` input port is connected.

Port I/O Specification

See Ports & Connections for general wiring rules, data type colors, and dynamic port creation.

Input Ports

Port Nature: Fixed Input Ports (1 total).

Port Name	Port ID	Data Type	Required	Visibility Condition	Description
`Value`	`data`	`Bytes`	Required	Always visible	Input byte array (`Uint8Array`) treated as a contiguous big-endian bit stream.

Output Ports

Port Nature: Fixed Output Ports (1 total).

Port Name	Port ID	Data Type	Visibility Condition	Description
`Result`	`result`	`Bytes`	Always visible	Shifted or rotated byte array (`Uint8Array`) of the same byte length as `Data`.

Error Cases

When any of the following conditions occurs at runtime, this node transitions to an ERROR state and downstream nodes connected to its outputs do not execute.

Error Code	Default Engine Message	Trigger Condition
`BYTES_INVALID_ARGUMENT`	Invalid argument value	Raised when an argument (such as bit shift count, byte length, or negative integer) is invalid or negative.

Examples

Shifting a 16-Byte Block Left by 1 Bit (CMAC Subkey Step)

Shift a 128-bit block left by 1 bit across byte boundaries.

Set Operation to SHL (Bit Shift Left <<) and Bits to 1.
Connect a 16-byte buffer to Data; Result emits the 16-byte buffer shifted left by 1 bit.