Convert map[interface {}]interface {} to map[string]string

From a source I cannot influence I am given data in a map, which arrives as map[interface {}]interface {}.

I need to process the contained data, preferably as map[string]string (the data within is perfectly suitable for that).

I need to generate a list of the keys from the data as well, as those are not known beforehand.

Most similar questions I could find on the web say more or less, that this is impossible, but if my map is m, fmt.Println(m) shows the data is there, readable as map[k0:v0 K1:v1 k2:v2 ... ].

How can I do what fmt.Println is able to do?

A secure way to process unknown interfaces, just use fmt.Sprintf()

https://play.golang.org/p/gOiyD4KpQGz

package main

import (
	"fmt"
)

func main() {

	mapInterface := make(map[interface{}]interface{})	
	mapString := make(map[string]string)

	mapInterface["k1"] = 1
	mapInterface[3] = "hello"
	mapInterface["world"] = 1.05

	for key, value := range mapInterface {
		strKey := fmt.Sprintf("%v", key)
		strValue := fmt.Sprintf("%v", value)

		mapString[strKey] = strValue
	}

	fmt.Printf("%#v", mapString)
}

Perhaps I misunderstand the question, but would this work?

m := make(map[interface{}]interface{})
m["foo"] = "bar"

m2 := make(map[string]string)   

for key, value := range m {        
    switch key := key.(type) {
    case string:
        switch value := value.(type) {
        case string:
        	m2[key] = value
        }
    }
}

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-html -->

// data is map[string]interface{}

form := make(map[string]string)

for k, v := range data {
    form[k] = v.(string)
}

<!-- end snippet -->