Block Padding

Category: Utility · Node Type ID: padding-block-pad

Applies cryptographic block padding (PKCS#7, ANSI X9.23, ISO/IEC 9797-1 Method 1/2/3, NIST SP 800-38B, None)

Overview

Applies a cryptographic block padding scheme to an arbitrary-length byte array so its output length is an exact multiple of the selected Block Size (Bytes) (8, 16, or 32 bytes).

Supports all 7 padding options documented in Padding Schemes: PKCS#7 (RFC 5652), ISO/IEC 9797-1 Method 2 (ISO/IEC 7816-4), ISO/IEC 9797-1 Method 3, NIST SP 800-38B (CMAC conditional), ANSI X9.23, ISO/IEC 9797-1 Method 1 (Zero Padding), and None.

When to Use

Explicitly padding data before feeding it into a cipher node configured with Padding = None so you can inspect the exact padded block bytes on the canvas.
Using specialized padding rules not built directly into a cipher node's dropdown (such as NIST80038B conditional padding or 32-byte block padding).

Parameter Configuration

Parameter (ID)	Type & Default	Visibility Condition	Description & Options
Padding Standard `paddingType`	`select` Default: `None`	Always visible	Selects the block padding standard to apply. See Padding Schemes for byte-level diagrams and examples of each rule. `None`: None `Zero`: ISO/IEC 9797-1 Method 1 (Zero Padding) `ISO7816`: ISO/IEC 9797-1 Method 2 (ISO/IEC 7816-4) `ISO97971M3`: ISO/IEC 9797-1 Method 3 `PKCS7`: PKCS#7 (RFC 5652) `NIST80038B`: NIST SP 800-38B `ANSIX923`: ANSI X9.23
Block Size (Bytes) `blockSize`	`select` Default: `16`	Always visible	Target block size in bytes: `8` (64-bit, DES/3DES), `16` (128-bit, AES/SEED/ARIA/Camellia/SM4), or `32` (256-bit). `8`: 8 Bytes (64 bits - DES/3DES) `16`: 16 Bytes (128 bits - AES/SEED/ARIA/Camellia/SM4) `32`: 32 Bytes (256 bits)
Unify Errors `errorUnify`	`boolean` Default: `false` Supports Variable Reference (`$var`: `bool`)	Always visible	Replaces built-in errors with a custom error code/message when enabled.
Unified Error Code `errorUnifyCode`	`text` Default: `""` (empty) Supports Variable Reference (`$var`: `string`)	When `errorUnify` is `true`	Custom error code when Unify Errors is enabled.
Unified Error Message `errorUnifyMessage`	`text` Default: `""` (empty) Supports Variable Reference (`$var`: `string`)	When `errorUnify` is `true`	Custom error message when Unify Errors is enabled.

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
`Data`	`data`	`Bytes`	Required	Always visible	Unpadded input byte array (`Uint8Array`).

Output Ports

Port Nature: Fixed Output Ports (1 total).

Port Name	Port ID	Data Type	Visibility Condition	Description
`Padded Data`	`result`	`Bytes`	Always visible

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. Enabling Unify Errors (errorUnify) replaces all error codes below with your configured unified error code and message.

Error Code	Default Engine Message	Trigger Condition
`PLAINTEXT_NOT_BLOCK_ALIGNED`	In NoPad mode the plaintext length must be a multiple of the block size	Raised only when `Padding Standard = None` and the input `Data` byte length is not already a multiple of `Block Size`.

Examples

Inspecting PKCS#7 Padding Before AES-ECB Encryption

Pad a 10-byte message to 16 bytes and inspect the 0x06 padding bytes.

Connect a 10-byte input to Block Padder with Padding Standard = PKCS#7 and Block Size = 16.
Connect Padded Data both to an Output Inspector (showing 6 trailing 06 bytes) and to AES Encrypt (with Padding = None).