How to Get a MD5 Hash from a String in Go

Created Jun 23, 2022 at 8:41

Modified Jun 23, 2022 at 9:20

Using Sum Function

The md5.Sum() function returns the MD5 checksum of the data.

The following example should cover whatever you are trying to do:

package main

import (
  "crypto/md5"
  "encoding/hex"
  "fmt"
)

func main() {
  b := []byte("Hello")

  out := md5.Sum(b)
  fmt.Printf("%x\n", out)

  // EncodeToString
  fmt.Println(hex.EncodeToString(out[:]))
}

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Using New Function

New returns a new hash.Hash computing the MD5 checksum. The Hash also implements encoding.BinaryMarshaler and encoding.BinaryUnmarshaler to marshal and unmarshal the internal state of the hash.

For example,

package main

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

func main() {

  h := md5.New()
  io.WriteString(h, "Hello")
  io.WriteString(h, "Word")

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

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Generate MD5 checksum of a file. See the following example:

package main

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

func main() {
  f, err := os.Open("ins.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\n", h.Sum(nil))
}