Go SHA-256 Hash Code Example (Online Runner)

Go SHA-256 hashing code example with runnable snippets to calculate SHA-256 for text and files.

Online calculator: use the site SHA-256 text tool.

Calculation method

Use crypto/sha256, hash UTF-8 bytes, and encode the 32-byte digest as hex.

Implementation notes

Package: built-in crypto/sha256.
Implementation: file hashing streams bytes to avoid loading large files into memory.
Notes: SHA-256 is not keyed; use HMAC for authentication or Argon2/scrypt for passwords.

Text hashing example

package main

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
)

func sha256Text(text string) string {
	sum := sha256.Sum256([]byte(text))
	return hex.EncodeToString(sum[:])
}

func main() {
	fmt.Println(sha256Text("hello world"))
}

File hashing example

package main

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"io"
	"os"
)

func sha256File(path string) (string, error) {
	file, err := os.Open(path)
	if err != nil {
		return "", err
	}
	defer file.Close()

	hash := sha256.New()
	if _, err := io.Copy(hash, file); err != nil {
		return "", err
	}
	return hex.EncodeToString(hash.Sum(nil)), nil
}

func main() {
	file, err := os.CreateTemp("", "sha256-example-*.bin")
	if err != nil {
		panic(err)
	}
	defer os.Remove(file.Name())
	if _, err := file.Write([]byte("example payload\n")); err != nil {
		panic(err)
	}
	if err := file.Close(); err != nil {
		panic(err)
	}

	value, err := sha256File(file.Name())
	if err != nil {
		panic(err)
	}
	fmt.Println(value)
}

Complete script (implementation + tests)

package main

import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"io"
	"os"
)

func sha256Hex(data []byte) string {
	sum := sha256.Sum256(data)
	return hex.EncodeToString(sum[:])
}

func sha256Text(text string) string {
	return sha256Hex([]byte(text))
}

func sha256File(path string) (string, error) {
	file, err := os.Open(path)
	if err != nil {
		return "", err
	}
	defer file.Close()

	hash := sha256.New()
	if _, err := io.Copy(hash, file); err != nil {
		return "", err
	}
	return hex.EncodeToString(hash.Sum(nil)), nil
}

func main() {
	vectors := map[string]string{
		"":                "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
		"abc":             "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad",
		"message digest":  "f7846f55cf23e14eebeab5b4e1550cad5b509e3348fbc4efa3a1413d393cb650",
		"abcdefghijklmnopqrstuvwxyz": "71c480df93d6ae2f1efad1447c66c9525e316218cf51fc8d9ed832f2daf18b73",
	}

	for input, expected := range vectors {
		if got := sha256Text(input); got != expected {
			panic(fmt.Sprintf("SHA-256 mismatch for %q: %s != %s", input, got, expected))
		}
	}

	file, err := os.CreateTemp("", "sha256-example-*.bin")
	if err != nil {
		panic(err)
	}
	defer os.Remove(file.Name())
	if _, err := file.Write([]byte("example payload\n")); err != nil {
		panic(err)
	}
	if err := file.Close(); err != nil {
		panic(err)
	}

	fileHash, err := sha256File(file.Name())
	if err != nil {
		panic(err)
	}
	fmt.Println("sha256(file)=", fileHash)
	fmt.Println("All SHA-256 test vectors passed.")
}