SM4 Encrypt

Category: Symmetric Ciphers · Node Type ID: symmetric-sm4-encrypt

Chinese National Standard SM4 128-bit Block Cipher (GB/T 32907 / GM/T 0002)

Overview

Encrypts data using the Chinese national standard 128-bit unbalanced Feistel block cipher SM4 (GB/T 32907-2016 / GM/T 0002-2012 / ISO/IEC 18033-3:2021) with a fixed 128-bit (16-byte) key and 32 rounds.

Supports CBC, GCM, CTR, ECB, CFB, and OFB modes over 16-byte blocks.

When to Use

Implementing ShangMi (SM) cryptographic suites, TLS 1.3 SM4 cipher suites (RFC 8998), or Chinese commercial cryptography compliance tests.
Testing GB/T 32907 16-byte block test vectors.

Parameter Configuration

Parameter (ID)	Type & Default	Visibility Condition	Description & Options
Cipher Mode `mode`	`select` Default: `ECB`	Always visible	Selects the operating mode (`CBC`, `GCM`, `CTR`, `ECB`, `CFB`, or `OFB`). See Block Cipher Modes for full details. `ECB`: ECB (Electronic Codebook) `CBC`: CBC (Cipher Block Chaining) `GCM`: GCM (AEAD) `CTR`: CTR (Counter Mode)
Padding `padding`	`select` Default: `None`	Always visible	16-byte block padding scheme applied in `ECB` and `CBC` modes. See Padding Schemes for full details. `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
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 (5 total; conditionally visible ports depend on parameter settings as shown below).

Port Name	Port ID	Data Type	Required	Visibility Condition	Description
`Key`	`key`	`Bytes` (16B)	Required	Always visible	16-byte (128-bit) SM4 secret key.
`Plaintext`	`plaintext`	`Bytes`	Required	Always visible	Plaintext bytes (`Uint8Array`) to encrypt.
`IV`	`iv`	`Bytes` (16B)	Optional	When `mode` is `CBC` or `CTR`	16-byte IV for `CBC`, `CTR`, `CFB`, and `OFB` modes (defaults to 16 zero bytes if unconnected).
`Nonce`	`nonce`	`Bytes` (12B)	Optional	When `mode` is `GCM`	12-byte AEAD nonce for `GCM` mode (defaults to 12 zero bytes if unconnected).
`AAD`	`aad`	`Bytes` (GCM only)	Optional	When `mode` is `GCM`	Optional Additional Authenticated Data for `GCM` mode.

Output Ports

Port Nature: Fixed Output Ports (2 total; conditionally visible ports depend on parameter settings as shown below).

Port Name	Port ID	Data Type	Visibility Condition	Description
`Ciphertext`	`ciphertext`	`Bytes`	Always visible	Encrypted output bytes (`Uint8Array`).
`Auth Tag`	`tag`	`Bytes` (GCM)	When `mode` is `GCM`	16-byte authentication tag produced in `GCM` mode.

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
`INVALID_KEY_LENGTH`	Invalid key length	Raised when `Key` is not exactly 16 bytes.
`INVALID_IV_LENGTH`	Invalid IV length	Raised when a connected `IV` is not 16 bytes or `Nonce` is not 12 bytes.
`PLAINTEXT_NOT_BLOCK_ALIGNED`	In NoPad mode the plaintext length must be a multiple of the block size	Raised in `ECB`/`CBC` mode when `Padding = None` and `Plaintext` length is not a multiple of 16 bytes.
`INVALID_NONCE_LENGTH`	Invalid nonce length	Raised when a connected AEAD or stream-cipher `Nonce` is not 12 bytes (96 bits).

Examples

Encrypting with SM4-GCM (RFC 8998)

Perform authenticated encryption using a 16-byte SM4 key and 12-byte nonce.

Set Cipher Mode to GCM.
Connect a 16-byte key to Key, a 12-byte nonce to Nonce, and your data to Plaintext.