gm-crypto

SM4 is a block cipher algorithm. It supports multiple modes of operation, including:

• ECB: Electronic Codebook
• CBC: Cipher Block Chaining

To use CBC mode, you must provide an iv (Initialization Vector). The key should be a string of 32 hexadecimal digits. You can specify inputEncoding, outputEncoding, mode, and iv in the options object.

const { SM4 } = require('gm-crypto')

const key = '0123456789abcdeffedcba9876543210' // Any string of 32 hexadecimal digits
const originalData = 'SM4 国标对称加密'

let encryptedData, decryptedData

// ECB mode
encryptedData = SM4.encrypt(originalData, key, {
  inputEncoding: 'utf8',
  outputEncoding: 'base64'
})
decryptedData = SM4.decrypt(encryptedData, key, {
  inputEncoding: 'base64',
  outputEncoding: 'utf8'
})

// CBC mode
const iv = '0123456789abcdeffedcba9876543210' // Initialization vector (32 hex digits)
encryptedData = SM4.encrypt(originalData, key, {
  iv: iv,
  mode: SM4.constants.CBC,
  inputEncoding: 'utf8',
  outputEncoding: 'hex'
})
decryptedData = SM4.decrypt(encryptedData, key, {
  iv: iv,
  mode: SM4.constants.CBC,
  inputEncoding: 'hex',
  outputEncoding: 'utf8'
})

Use decrypt(data, privateKey, options) to decrypt an SM2 ciphertext using an SM2 private key.

Parameters:

• data: The ciphertext to decrypt. Can be a string, Buffer, or ArrayBuffer.
• privateKey: The recipient's SM2 private key as a hex string.
• options: An optional configuration object:
  • mode: Must match the mode used during encryption (C1C2C3 or C1C3C2). Default is C1C3C2.
  • inputEncoding: The encoding of the input data if it is a string.
  • outputEncoding: If provided, the decrypted plaintext is returned as a string with this encoding. If omitted, it returns an ArrayBuffer.
  • pc: A boolean. If true, the function expects the ciphertext to be prefixed with 04.

Returns: The decrypted plaintext as an ArrayBuffer (default) or a string (if outputEncoding is specified). If decryption or integrity verification fails, it returns an empty ArrayBuffer (or empty string if outputEncoding is set).

import { decrypt } from 'gm-crypto/sm2';

const privateKey = '...'; // Your SM2 private key
const ciphertext = '...'; // The ciphertext from encrypt()

// Decrypting to an ArrayBuffer
const plaintextBuffer = decrypt(ciphertext, privateKey, { mode: 'C1C2C3' });

// Decrypting to a UTF-8 string
const plaintext = decrypt(ciphertext, privateKey, { 
  mode: 'C1C2C3', 
  outputEncoding: 'utf8' 
});

Use encrypt(data, publicKey, options) to encrypt a message using an SM2 public key.

Parameters:

• data: The plaintext to encrypt. Can be a string, Buffer, or ArrayBuffer.
• publicKey: The recipient's SM2 public key as a hex string.
• options: An optional configuration object:
  • mode: The concatenation order of the ciphertext components. Supported values: C1C2C3 or C1C3C2 (default is C1C3C2).
  • inputEncoding: The encoding of the input data if it is a string (default: 'utf8').
  • outputEncoding: If provided, the function returns a string with this encoding. If omitted, it returns an ArrayBuffer.
  • pc: A boolean. If true, the output ciphertext is prefixed with 04.

Returns: An ArrayBuffer (default) or a string (if outputEncoding is specified).

import { encrypt } from 'gm-crypto/sm2';

const publicKey = '04...'; // Your SM2 public key
const data = 'Hello SM2';

// Encrypting to an ArrayBuffer
const ciphertext = encrypt(data, publicKey, { mode: 'C1C2C3' });

// Encrypting to a hex string
const ciphertextHex = encrypt(data, publicKey, { 
  mode: 'C1C2C3', 
  outputEncoding: 'hex' 
});

Use the encrypt function to perform SM4 encryption.

Parameters:

• data: The plaintext to encrypt. Can be a string, Buffer, or ArrayBuffer.
• key: A 32-character hexadecimal string representing the 128-bit key.
• options: An object containing:
  • mode: Either constants.ECB or constants.CBC.
  • iv: A 32-character hexadecimal string representing the Initialization Vector (required if mode is CBC).
  • inputEncoding: The encoding of the input data if it is a string (defaults to 'utf8').
  • outputEncoding: If provided, the function returns the ciphertext as a string in this encoding. If omitted, it returns an ArrayBuffer.

import { encrypt, constants } from 'gm-crypto/src/lib/sm4';

const key = '0123456789abcdef0123456789abcdef';
const iv = 'abcdef0123456789abcdef0123456789';
const data = 'hello world';

// CBC Mode (requires IV)
const ciphertext = encrypt(data, key, {
  mode: constants.CBC,
  iv: iv,
  outputEncoding: 'hex'
});

Use the decrypt function to decrypt SM4 ciphertext.

Parameters:

• data: The ciphertext to decrypt. Can be a string, Buffer, or ArrayBuffer.
• key: A 32-character hexadecimal string representing the 128-bit key.
• options: An object containing:
  • mode: Either constants.ECB or constants.CBC.
  • iv: A 32-character hexadecimal string representing the Initialization Vector (required if mode is CBC).
  • inputEncoding: The encoding of the input data if it is a string.
  • outputEncoding: If provided, the function returns the decrypted plaintext as a string in this encoding. If omitted, it returns an ArrayBuffer.

import { decrypt, constants } from 'gm-crypto/src/lib/sm4';

const key = '0123456789abcdef0123456789abcdef';
const iv = 'abcdef0123456789abcdef0123456789';
const ciphertext = '...'; // hex string

const plaintext = decrypt(ciphertext, key, {
  mode: constants.CBC,
  iv: iv,
  inputEncoding: 'hex',
  outputEncoding: 'utf8'
});