sha1

package main

import (
	"crypto/sha1"
	"fmt"
	"io"
)

func main() {
	h := sha1.New()
	io.WriteString(h, "His money is twice tainted:")
	io.WriteString(h, " 'taint yours and 'taint mine.")
	fmt.Printf("% x", h.Sum(nil))
}

Output:
59 7f 6a 54 00 10 f9 4c 15 d7 18 06 a9 9a 2c 87 10 e7 47 bd

package main

import (
	"crypto/sha1"
	"fmt"
	"io"
	"log"
	"os"
)

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

	h := sha1.New()
	if _, err := io.Copy(h, f); err != nil {
		log.Fatal(err)
	}

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

Output:

package main

import (
	"crypto/sha1"
	"fmt"
)

func main() {
	data := []byte("This page intentionally left blank.")
	fmt.Printf("% x", sha1.Sum(data))
}

Output:
af 06 49 23 bb f2 30 15 96 aa c4 c2 73 ba 32 17 8e bc 4a 96