rework program flow

This commit is a complete rebuild of pkictl. Before everything was all
over the place and adding new commands was kind of a hassle.

Now each command has its own file and can be adjusted on a command
basis. Options are still used by the same name, but can now use
different descriptions.

1 files changed, 80 insertions, 0 deletions

diff --git a/create_private_key.go b/create_private_key.go
new file mode 100644
index 0000000..c13889f
--- /dev/null
+++ b/create_private_key.go
@@ -0,0 +1,80 @@
+package main
+
+import (
+	"crypto/elliptic"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/gibheer/pki"
+)
+
+const (
+	// Lower boundary limit for RSA private keys
+	RsaLowerLength = 1024
+	// Upper boundary limit for RSA private keys
+	RsaUpperLength = 65536
+)
+
+var (
+	// the possible ecdsa curves allowed to be used
+	ecdsaCurves = map[uint]elliptic.Curve{
+		224: elliptic.P224(),
+		256: elliptic.P256(),
+		384: elliptic.P384(),
+		521: elliptic.P521(),
+	}
+)
+
+func CreatePrivateKey(args []string) error {
+	fs := flag.NewFlagSet("pkiadm create-private-key", flag.ExitOnError)
+	fs.Usage = func() {
+		fmt.Fprintf(os.Stderr, "The length depends on the key type. Possible values are:\n")
+		fmt.Fprintf(os.Stderr, "  * ed25519 - 256\n")
+		fmt.Fprintf(os.Stderr, "  * ecdsa   - 224, 256, 384, 521\n")
+		fmt.Fprintf(os.Stderr, "  * rsa     - from %d up to %d\n", RsaLowerLength, RsaUpperLength)
+		fmt.Fprintf(os.Stderr, "Usage of %s %s:\n", COMMAND, "create-private")
+		fs.PrintDefaults()
+	}
+	flagType := fs.String("type", "ed25519", "the type of the private key (ed25519, ecdsa, rsa)")
+	flagLength := fs.Uint("length", 256, "the bit length for the private key")
+	flagOutput := fs.String("output", "stdout", "write private key to file")
+	fs.Parse(args)
+
+	var err error
+	var out io.WriteCloser
+	if *flagOutput == "stdout" {
+		out = os.Stdout
+	} else {
+		out, err = os.OpenFile(*flagOutput, os.O_WRONLY|os.O_CREATE|os.O_EXCL|os.O_SYNC, 0700)
+		if err != nil {
+			return err
+		}
+	}
+	defer out.Close()
+
+	var pk pki.Pemmer
+	switch *flagType {
+	case "ed25519":
+		if *flagLength != 256 {
+			return fmt.Errorf("ed25519 only supports bit length of 256")
+		}
+		pk, err = pki.NewPrivateKeyEd25519()
+	case "ecdsa":
+		if curve, found := ecdsaCurves[*flagLength]; !found {
+			return fmt.Errorf("unknown bit length for ecdsa")
+		} else {
+			pk, err = pki.NewPrivateKeyEcdsa(curve)
+		}
+	case "rsa":
+		if RsaLowerLength > *flagLength || *flagLength > RsaUpperLength {
+			return fmt.Errorf("bit length outside of range for rsa")
+		}
+		pk, err = pki.NewPrivateKeyRsa(int(*flagLength))
+	default:
+		return fmt.Errorf("unknown private key type")
+	}
+
+	return writePem(pk, out)
+}