添加功能

node_modules/sm-crypto/src/sm2/asn1.js

@@ -0,0 +1,161 @@
+/* eslint-disable class-methods-use-this */
+const {BigInteger} = require('jsbn')
+
+function bigintToValue(bigint) {
+  let h = bigint.toString(16)
+  if (h[0] !== '-') {
+    // 正数
+    if (h.length % 2 === 1) h = '0' + h // 补齐到整字节
+    else if (!h.match(/^[0-7]/)) h = '00' + h // 非0开头，则补一个全0字节
+  } else {
+    // 负数
+    h = h.substr(1)
+
+    let len = h.length
+    if (len % 2 === 1) len += 1 // 补齐到整字节
+    else if (!h.match(/^[0-7]/)) len += 2 // 非0开头，则补一个全0字节
+
+    let mask = ''
+    for (let i = 0; i < len; i++) mask += 'f'
+    mask = new BigInteger(mask, 16)
+
+    // 对绝对值取反，加1
+    h = mask.xor(bigint).add(BigInteger.ONE)
+    h = h.toString(16).replace(/^-/, '')
+  }
+  return h
+}
+
+class ASN1Object {
+  constructor() {
+    this.tlv = null
+    this.t = '00'
+    this.l = '00'
+    this.v = ''
+  }
+
+  /**
+   * 获取 der 编码比特流16进制串
+   */
+  getEncodedHex() {
+    if (!this.tlv) {
+      this.v = this.getValue()
+      this.l = this.getLength()
+      this.tlv = this.t + this.l + this.v
+    }
+    return this.tlv
+  }
+
+  getLength() {
+    const n = this.v.length / 2 // 字节数
+    let nHex = n.toString(16)
+    if (nHex.length % 2 === 1) nHex = '0' + nHex // 补齐到整字节
+
+    if (n < 128) {
+      // 短格式，以 0 开头
+      return nHex
+    } else {
+      // 长格式，以 1 开头
+      const head = 128 + nHex.length / 2 // 1(1位) + 真正的长度占用字节数(7位) + 真正的长度
+      return head.toString(16) + nHex
+    }
+  }
+
+  getValue() {
+    return ''
+  }
+}
+
+class DERInteger extends ASN1Object {
+  constructor(bigint) {
+    super()
+
+    this.t = '02' // 整型标签说明
+    if (bigint) this.v = bigintToValue(bigint)
+  }
+
+  getValue() {
+    return this.v
+  }
+}
+
+class DERSequence extends ASN1Object {
+  constructor(asn1Array) {
+    super()
+
+    this.t = '30' // 序列标签说明
+    this.asn1Array = asn1Array
+  }
+
+  getValue() {
+    this.v = this.asn1Array.map(asn1Object => asn1Object.getEncodedHex()).join('')
+    return this.v
+  }
+}
+
+/**
+ * 获取 l 占用字节数
+ */
+function getLenOfL(str, start) {
+  if (+str[start + 2] < 8) return 1 // l 以0开头，则表示短格式，只占一个字节
+  return +str.substr(start + 2, 2) & 0x7f + 1 // 长格式，取第一个字节后7位作为长度真正占用字节数，再加上本身
+}
+
+/**
+ * 获取 l
+ */
+function getL(str, start) {
+  // 获取 l
+  const len = getLenOfL(str, start)
+  const l = str.substr(start + 2, len * 2)
+
+  if (!l) return -1
+  const bigint = +l[0] < 8 ? new BigInteger(l, 16) : new BigInteger(l.substr(2), 16)
+
+  return bigint.intValue()
+}
+
+/**
+ * 获取 v 的位置
+ */
+function getStartOfV(str, start) {
+  const len = getLenOfL(str, start)
+  return start + (len + 1) * 2
+}
+
+module.exports = {
+  /**
+   * ASN.1 der 编码，针对 sm2 签名
+   */
+  encodeDer(r, s) {
+    const derR = new DERInteger(r)
+    const derS = new DERInteger(s)
+    const derSeq = new DERSequence([derR, derS])
+
+    return derSeq.getEncodedHex()
+  },
+
+  /**
+   * 解析 ASN.1 der，针对 sm2 验签
+   */
+  decodeDer(input) {
+    // 结构：
+    // input = | tSeq | lSeq | vSeq |
+    // vSeq = | tR | lR | vR | tS | lS | vS |
+    const start = getStartOfV(input, 0)
+
+    const vIndexR = getStartOfV(input, start)
+    const lR = getL(input, start)
+    const vR = input.substr(vIndexR, lR * 2)
+
+    const nextStart = vIndexR + vR.length
+    const vIndexS = getStartOfV(input, nextStart)
+    const lS = getL(input, nextStart)
+    const vS = input.substr(vIndexS, lS * 2)
+
+    const r = new BigInteger(vR, 16)
+    const s = new BigInteger(vS, 16)
+
+    return {r, s}
+  }
+}