Go: Hash checksums

String

To compute the checksum of a string or byte slice, use the Sum function from a crypto package such as crypto/md5, crypto/sha1, or crypto/sha256:

s := "Foo"

md5 := md5.Sum([]byte(s))
sha1 := sha1.Sum([]byte(s))
sha256 := sha256.Sum256([]byte(s))

fmt.Printf("%x\n", md5)
fmt.Printf("%x\n", sha1)
fmt.Printf("%x\n", sha256)

1356c67d7ad1638d816bfb822dd2c25d
201a6b3053cc1422d2c3670b62616221d2290929
1cbec737f863e4922cee63cc2ebbfaafcd1cff8b790d8cfd2e6a5d550b648afa

File

To compute the checksum of a file or other input stream:

• create a new hash.Hash from a crypto package such as crypto/md5, crypto/sha1, or crypto/sha256,
• add data by writing to its io.Writer function,
• extract the checksum by calling its Sum function.

input := strings.NewReader("Foo")

hash := sha256.New()
if _, err := io.Copy(hash, input); err != nil {
        log.Fatal(err)
}
sum := hash.Sum(nil)

fmt.Printf("%x\n", sum)

1cbec737f863e4922cee63cc2ebbfaafcd1cff8b790d8cfd2e6a5d550b648afa