md5

package main

import (
	"crypto/md5"
	"fmt"
	"io"
)

func main() {
	h := md5.New()
	io.WriteString(h, "The fog is getting thicker!")
	io.WriteString(h, "And Leon's getting laaarger!")
	fmt.Printf("%x", h.Sum(nil))
}

Output:

e2c569be17396eca2a2e3c11578123ed

package main

import (
	"crypto/md5"
	"fmt"
	"io"
	"log"
	"os"
)

func main() {
	f, err := os.Open("file.txt")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	h := md5.New()
	if _, err := io.Copy(h, f); err != nil {
		log.Fatal(err)
	}

	fmt.Printf("%x", h.Sum(nil))
}

package main

import (
	"crypto/md5"
	"fmt"
)

func main() {
	data := []byte("These pretzels are making me thirsty.")
	fmt.Printf("%x", md5.Sum(data))
}

Output:

b0804ec967f48520697662a204f5fe72