前端RSA公钥解密-526互联

前端加解密使用的jsencrypt包，jsencrypt包中只有公钥加密，私钥解密的方法，但项目中要求前端公钥解密，通过重写jsencrypt包中的方法来实现

/**
 *  重写JSEncrypt解密方法以支持公钥解密
 * */
private pkcs1unpad2(d, n) {
  const b = d.toByteArray();
  let i = 0;
  while (i < b.length && b[i] === 0) {
    ++i;
  }
  // if (b.length - i !== n - 1 || b[i] !== 2) {
  //   return null
  // }
  ++i;
  while (b[i] !== 0) {
    if (++i >= b.length) {
      return null;
    }
  }
  let ret = '';
  while (++i < b.length) {
    const c = b[i] & 255;
    if (c < 128) { // utf-8 decode
      ret += String.fromCharCode(c);
    } else if ((c > 191) && (c < 224)) {
      ret += String.fromCharCode(((c & 31) << 6) | (b[i + 1] & 63));
      ++i;
    } else {
      ret += String.fromCharCode(((c & 15) << 12) | ((b[i + 1] & 63) << 6) | (b[i + 2] & 63));
      i += 2;
    }
  }
  return ret;
}

public rsaDecryFn(str，pubKey) {

  if (str) {
    const encrypt: any = new JSEncrypt();
    encrypt.setPublicKey(pubKey);
    // 自定义解析方法支持公钥解析
    const rsaKey: any = encrypt.getKey();
    const that = this;
    rsaKey.decrypt = function(ctext) {
      const c = parseBigInt(ctext, 16);
      const m = this.doPublic(c);
      if (m == null) {
        return null;
      }
      return that.pkcs1unpad2(m, (this.n.bitLength() + 7) >> 3);
    };
    rsaKey.decryptLong = function (text: string) {
      const maxLength = ((this.n.bitLength() + 7) >> 3);
      try {
        if (text.length > maxLength) {
          let ct = '';
          const lt = text.match(/.{1,256}/g);
          lt.forEach((entry) => {
            const t1 = (this as any).decrypt(entry);
            ct += t1;
          });
          return ct;
        }
        const y = this.decrypt(text);
        return y;
      } catch (ex) {
        return false;
      }
    };
    try {
      return encrypt.getKey().decryptLong(b64tohex(str));
    } catch (ex) {
      return false;
    }
  }
  return str;
}


调用rsaDecryFn方法来公钥解密

公钥