基于base54算法实现的标识符混淆，支持toplevel设置

gistfile1.txt

const parser = require('@babel/parser');
const traverse = require('@babel/traverse').default;
const generate = require('@babel/generator').default;
const code1 = `
const ssh = 'sshssh';
(function parc(moo, man){
    try {
            console.log(ssh);
            var foobar = 10;
            function bbb() {
                const ssh2 = 'sshsshsshssh';
                console.log(foobar);
                (function () {
                    console.log(ssh2);
                })();
            }
            function ccc() {
                const ssh3 = 'sshsshssh';
                (function () {
                    console.log(ssh3);
                })();
            }
            return parc(foobar + moo + man);
    } catch(ex) {
            log(ex);
            return foobar;
    }
})();
`;

const code2 = `
const ssh = 'sshssh';
(function parc(moo, man){
    try {
            console.log(ssh);
            var foobar = 10;
            function aaa() {
                eval('console.log(foobar)');
            }
            function bbb() {
                const ssh2 = 'sshsshsshssh';
                console.log(foobar);
                (function () {
                    console.log(ssh2);
                })();
            }
            function ccc() {
                const ssh3 = 'sshsshssh';
                (function () {
                    console.log(ssh3);
                })();
            }
            return parc(foobar + moo + man);
    } catch(ex) {
            log(ex);
            return foobar;
    }
})();
`;

const base54 = (function(){
    var DIGITS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$_";
    return function(num) {
            var ret = "";
            do {
                    ret = DIGITS.charAt(num % 54) + ret;
                    num = Math.floor(num / 54);
            } while (num > 0);
            return ret;
    };
})();


const defaultOptions = {
    toplevel: false
}
function mangle(code, { toplevel } = defaultOptions) {
    const ast = parser.parse(code);

    let uid = 0;
    traverse(ast, {
        CallExpression(path) {
            if (path.node) {
                if(generate(path.node.callee).code === 'eval') {
                    let scope = path.scope
                    while(scope) {
                        scope.hasEval = true;
                        scope = scope.parent
                    }
                }
            }
        }
    });
    traverse(ast, {
        Scopable: {
            exit(path) {
                if(!toplevel && !path.scope.parent) {
                    return;
                }
                if(path.scope.hasEval) {
                    return;
                }
                Object.entries(path.scope.bindings).forEach(([key, binding]) => {
                    if(binding.mangled) return;
                    binding.mangled = true;
                    const newName = base54(uid++);
                    binding.path.scope.rename(key, newName)
                })
            }
        }
    });
    return generate(ast).code
}

console.log('toplevel也混淆:\n', mangle(code1, { toplevel: true }));
console.log('\ntoplevel不混淆:\n', mangle(code1));

console.log('\n有eval:\n', mangle(code2));

结果

toplevel也混淆:
 const j = 'sshssh';

(function f(g, h) {
  try {
    console.log(j);
    var i = 10;

    function c() {
      const a = 'sshsshsshssh';
      console.log(i);

      (function () {
        console.log(a);
      })();
    }

    function d() {
      const b = 'sshsshssh';

      (function () {
        console.log(b);
      })();
    }

    return f(i + g + h);
  } catch (e) {
    log(e);
    return i;
  }
})();

toplevel不混淆:
 const ssh = 'sshssh';

(function f(g, h) {
  try {
    console.log(ssh);
    var i = 10;

    function c() {
      const a = 'sshsshsshssh';
      console.log(i);

      (function () {
        console.log(a);
      })();
    }

    function d() {
      const b = 'sshsshssh';

      (function () {
        console.log(b);
      })();
    }

    return f(i + g + h);
  } catch (e) {
    log(e);
    return i;
  }
})();

有eval:
 const ssh = 'sshssh';

(function parc(moo, man) {
  try {
    console.log(ssh);
    var foobar = 10;

    function aaa() {
      eval('console.log(foobar)');
    }

    function bbb() {
      const a = 'sshsshsshssh';
      console.log(foobar);

      (function () {
        console.log(a);
      })();
    }

    function ccc() {
      const b = 'sshsshssh';

      (function () {
        console.log(b);
      })();
    }

    return parc(foobar + moo + man);
  } catch (c) {
    log(c);
    return foobar;
  }
})();