// NewTripleDESCipher can also be used when EDE2 is required by
// duplicating the first 8 bytes of the 16-byte key.
ede2Key := []byte("example key 1234")
var tripleDESKey []byte
tripleDESKey = append(tripleDESKey, ede2Key[:16]...)
tripleDESKey = append(tripleDESKey, ede2Key[:8]...)
_, err := des.NewTripleDESCipher(tripleDESKey)
if err != nil {
    panic(err)
}
// See crypto/cipher for how to use a cipher.Block for encryption and
// decryption.