feat(sm2): support asn1 der encoded encryption/decryption

README.md

@@ -57,9 +57,11 @@ verifyResult = sm2.verifyPublicKey(compressedPublicKey) // 验证公钥
 ```js
 import { sm2 } from 'sm-crypto-v2'
 const cipherMode = 1 // 1 - C1C3C2，0 - C1C2C3，默认为1
+// 支持使用 asn1 对加密结果进行编码，在 options 参数中传入 { asn1: true } 即可，默认不开启
+let encryptData = sm2.doEncrypt(msgString, publicKey, cipherMode, { asn1: false }) // 加密结果
 
-let encryptData = sm2.doEncrypt(msgString, publicKey, cipherMode) // 加密结果
-let decryptData = sm2.doDecrypt(encryptData, privateKey, cipherMode) // 解密结果
+// 支持使用 asn1 对密文进行解码再解密，在 options 参数中传入 { asn1: true } 即可，默认不开启
+let decryptData = sm2.doDecrypt(encryptData, privateKey, cipherMode, { asn1: false }) // 解密结果
 
 encryptData = sm2.doEncrypt(msgArray, publicKey, cipherMode) // 加密结果，输入数组
 decryptData = sm2.doDecrypt(encryptData, privateKey, cipherMode, {output: 'array'}) // 解密结果，输出数组

src/sm2/asn1.ts

@@ -2,6 +2,7 @@
 
 import * as utils from '@noble/curves/abstract/utils';
 import { ONE } from './bn';
+import { utf8ToHex } from './utils';
 
 export function bigintToValue(bigint: bigint) {
   let h = bigint.toString(16)
@@ -81,6 +82,20 @@ class DERInteger extends ASN1Object {
   }
 }
 
+class DEROctetString extends ASN1Object {
+  public hV: string = ''
+  constructor(public s: string) {
+    super()
+
+    this.t = '04' // octstr 标签说明
+    if (s) this.v = s.toLowerCase()
+  }
+
+  getValue() {
+    return this.v
+  }
+}
+
 class DERSequence extends ASN1Object {
   public t = '30'
   constructor(public asn1Array: ASN1Object[]) {
@@ -134,6 +149,14 @@ export function encodeDer(r: bigint, s: bigint) {
   return derSeq.getEncodedHex()
 }
 
+export function encodeEnc(x: bigint, y: bigint, hash: string, cipher: string) {
+  const derX = new DERInteger(x)
+  const derY = new DERInteger(y)
+  const derHash = new DEROctetString(hash)
+  const derCipher = new DEROctetString(cipher)
+  const derSeq = new DERSequence([derX, derY, derHash, derCipher])
+  return derSeq.getEncodedHex()
+}
 /**
  * 解析 ASN.1 der，针对 sm2 验签
  */
@@ -145,7 +168,7 @@ export function decodeDer(input: string) {
 
   const vIndexR = getStartOfV(input, start)
   const lR = getL(input, start)
-  const vR = input.substr(vIndexR, lR * 2)
+  const vR = input.substring(vIndexR, vIndexR +lR * 2)
 
   const nextStart = vIndexR + vR.length
   const vIndexS = getStartOfV(input, nextStart)
@@ -159,3 +182,29 @@ export function decodeDer(input: string) {
 
   return { r, s }
 }
+
+/**
+ * 解析 ASN.1 der，针对 sm2 加密
+ */
+export function decodeEnc(input: string) {
+  // Extracts a sequence from the input based on the current start index.
+  function extractSequence(input: string, start: number): { value: string; nextStart: number } {
+    const vIndex = getStartOfV(input, start);
+    const length = getL(input, start);
+    const value = input.substring(vIndex, vIndex + length * 2);
+    const nextStart = vIndex + value.length;
+    return { value, nextStart };
+  }
+
+  const start = getStartOfV(input, 0);
+
+  const { value: vR, nextStart: startS } = extractSequence(input, start);
+  const { value: vS, nextStart: startHash } = extractSequence(input, startS);
+  const { value: hash, nextStart: startCipher } = extractSequence(input, startHash);
+  const { value: cipher } = extractSequence(input, startCipher);
+
+  const x = utils.hexToNumber(vR);
+  const y = utils.hexToNumber(vS);
+
+  return { x, y, hash, cipher };
+}

src/sm2/index.ts

@@ -1,5 +1,5 @@
 /* eslint-disable no-use-before-define */
-import { encodeDer, decodeDer } from './asn1'
+import { encodeDer, decodeDer, encodeEnc, decodeEnc } from './asn1'
 import { arrayToHex, arrayToUtf8, generateKeyPairHex, hexToArray, leftPad, utf8ToHex } from './utils'
 import { sm3 } from './sm3'
 import * as utils from '@noble/curves/abstract/utils';
@@ -18,7 +18,9 @@ export const EmptyArray = new Uint8Array()
 /**
  * 加密
  */
-export function doEncrypt(msg: string | Uint8Array, publicKey: string | ProjPointType<bigint>, cipherMode = 1) {
+export function doEncrypt(msg: string | Uint8Array, publicKey: string | ProjPointType<bigint>, cipherMode = 1, options?: {
+  asn1?: boolean // 使用 ASN.1 对 C1 编码
+}) {
 
   const msgArr = typeof msg === 'string' ? hexToArray(utf8ToHex(msg)) : Uint8Array.from(msg)
   const publicKeyPoint = typeof publicKey === 'string' ? sm2Curve.ProjectivePoint.fromHex(publicKey) :
@@ -29,6 +31,7 @@ export function doEncrypt(msg: string | Uint8Array, publicKey: string | ProjPoin
 
   // c1 = k * G
   let c1 = keypair.publicKey
+
   if (c1.length > 128) c1 = c1.substring(c1.length - 128)
   const p = publicKeyPoint.multiply(k)
 
@@ -41,7 +44,13 @@ export function doEncrypt(msg: string | Uint8Array, publicKey: string | ProjPoin
 
   xorCipherStream(x2, y2, msgArr)
   const c2 = bytesToHex(msgArr)
-
+  if (options?.asn1) {
+    const point = sm2Curve.ProjectivePoint.fromHex(keypair.publicKey)
+    const encode = cipherMode === C1C2C3 ? 
+     encodeEnc(point.x, point.y, c2, c3) :
+     encodeEnc(point.x, point.y, c3, c2)
+    return encode
+  }
   return cipherMode === C1C2C3 ? c1 + c2 + c3 : c1 + c3 + c2
 }
 
@@ -78,34 +87,53 @@ function xorCipherStream(x2: Uint8Array, y2: Uint8Array, msg: Uint8Array) {
  */
 export function doDecrypt(encryptData: string, privateKey: string, cipherMode?: number, options?: {
   output: 'array'
+  asn1?: boolean
 }): Uint8Array
 export function doDecrypt(encryptData: string, privateKey: string, cipherMode?: number, options?: {
-  output: 'string'
+  output: 'string',
+  asn1?: boolean
 }): string
 export function doDecrypt(encryptData: string, privateKey: string, cipherMode = 1, {
   output = 'string',
+  asn1 = false,
 } = {}) {
   const privateKeyInteger = utils.hexToNumber(privateKey)
 
-  let c3 = encryptData.substring(128, 128 + 64)
-  let c2 = encryptData.substring(128 + 64)
+  let c1: ProjPointType<bigint>
+  let c2: string
+  let c3: string
+
 
-  if (cipherMode === C1C2C3) {
-    c3 = encryptData.substring(encryptData.length - 64)
-    c2 = encryptData.substring(128, encryptData.length - 64)
+  if (asn1) {
+    const {x, y, cipher, hash} = decodeEnc(encryptData)
+    c1 = sm2Curve.ProjectivePoint.fromAffine({ x, y })
+    c3 = hash
+    c2 = cipher
+    if (cipherMode === C1C2C3) {
+      [c2, c3] = [c3, c2]
+    }
+  } else {
+    // c1c3c2
+    c1 = sm2Curve.ProjectivePoint.fromHex('04' + encryptData.substring(0, 128))!
+    c3 = encryptData.substring(128, 128 + 64)
+    c2 = encryptData.substring(128 + 64)
+
+    if (cipherMode === C1C2C3) {
+      c3 = encryptData.substring(encryptData.length - 64)
+      c2 = encryptData.substring(128, encryptData.length - 64)
+    }
   }
+
 
   const msg = hexToArray(c2)
-  const c1 = sm2Curve.ProjectivePoint.fromHex('04' + encryptData.substring(0, 128))!
-
   const p = c1.multiply(privateKeyInteger)
   const x2 = hexToArray(leftPad(utils.numberToHexUnpadded(p.x), 64))
   const y2 = hexToArray(leftPad(utils.numberToHexUnpadded(p.y), 64))
 
   xorCipherStream(x2, y2, msg)
   // c3 = hash(x2 || msg || y2)
   const checkC3 = arrayToHex(Array.from(sm3(utils.concatBytes(x2, msg, y2))))
-
+  
   if (checkC3 === c3.toLowerCase()) {
     return output === 'array' ? msg : arrayToUtf8(msg)
   } else {

test/sm2.test.ts

@@ -1,4 +1,5 @@
 import { sm2 } from '@/index'
+import { arrayToHex, hexToArray } from '@/sm2'
 import { expect, it, describe, beforeEach } from 'vitest'
 
 const cipherMode = 1 // 1 - C1C3C2，0 - C1C2C3
@@ -93,6 +94,36 @@ describe('sm2: encrypt and decrypt data', () => {
     });
 })
 
+
+describe('sm2: encrypt and decrypt data using asn1 encoding', () => {
+    it('decrypted data should be correct', () => {
+        const input = 'aabbccdd'
+        const res = sm2.doEncrypt(hexToArray(input), '049812a275eca335e85998eb4030a6cc9e88a098010bdbfc134b26e29c43253439d3821ef18e69e0813bcc55eee7dc9163f1edb81ad2032b20cbdf1408897faaac', 1, {
+            asn1: true,
+        })
+        // console.log('res', res)
+        const dec = sm2.doDecrypt(res, '75b25a5d6101013e9be25816f81cf1f64bf78ea8383b32d61f5b26e6f1429e70', 1, {
+            output: 'array',
+            asn1: true,
+        })
+        expect(arrayToHex([...dec])).toBe(input)
+    })
+    it('decrypted data should be correct: c1c2c3', () => {
+        const input = 'aabbccdd'
+        const res = sm2.doEncrypt(hexToArray(input), '049812a275eca335e85998eb4030a6cc9e88a098010bdbfc134b26e29c43253439d3821ef18e69e0813bcc55eee7dc9163f1edb81ad2032b20cbdf1408897faaac', 0, {
+            asn1: true,
+        })
+        // console.log('res', res)
+        const dec = sm2.doDecrypt(res, '75b25a5d6101013e9be25816f81cf1f64bf78ea8383b32d61f5b26e6f1429e70', 0, {
+            output: 'array',
+            asn1: true,
+        })
+        expect(arrayToHex([...dec])).toBe(input)
+    })
+
+})
+
+
 describe('sm2: sign data and verify sign', () => {
     it('signature and generate ec point', ({ unCompressedPublicKey, compressedPublicKey, privateKey }) => {
         for (const publicKey of [unCompressedPublicKey, compressedPublicKey]) {