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package main
import (
"crypto"
"crypto/rand"
"crypto/sha256"
"errors"
"flag"
"fmt"
"io"
"os"
// "crypto/ecdsa"
// "crypto/rsa"
)
type (
SignInputFlags struct {
Message string // the message to sign
PrivateKeyPath string // path to the private key
Output string // a path or stream to output the private key to
private_key crypto.Signer
output_stream io.Writer // the output stream for the CSR
}
)
func sign_input() {
flags := parse_sign_input_flags()
flags.private_key = load_private_key(flags.PrivateKeyPath)
output_stream, err := open_output_stream(flags.Output)
if err != nil {
crash_with_help(2, fmt.Sprintf("Error when creating file %s: %s", flags.Output, err))
}
flags.output_stream = output_stream
defer output_stream.Close()
if err := create_signature(flags); err != nil {
fmt.Fprintln(os.Stderr, "Error when creating signature", err)
os.Exit(3)
}
}
func parse_sign_input_flags() SignInputFlags {
flags := SignInputFlags{}
fs := flag.NewFlagSet("sign-input", flag.ExitOnError)
fs.StringVar(&flags.PrivateKeyPath, "private-key", "", "path to the private key file")
fs.StringVar(&flags.Output, "output", "STDOUT", "path where the generated signature should be stored")
fs.StringVar(&flags.Message, "message", "", "the message to sign")
fs.Parse(os.Args[2:])
return flags
}
func create_signature(flags SignInputFlags) error {
message := []byte(flags.Message)
// compute sha256 of the message
hash := sha256.New()
length, _ := hash.Write(message)
if length != len(message) { return errors.New("Error when creating hash over message!") }
// create signature of the hash using the private key
signature, err := flags.private_key.Sign(
rand.Reader,
hash.Sum([]byte("")),
nil,
)
if err != nil { return err }
flags.output_stream.Write(signature)
return nil
}
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