73 lines
1.5 KiB
Go
73 lines
1.5 KiB
Go
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package keygen
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import (
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"crypto/rand"
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"crypto/rsa"
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"crypto/x509"
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"encoding/pem"
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"fmt"
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"os"
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"github.com/spf13/cobra"
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"src.lwithers.me.uk/go/rsa/pkg/pemfile"
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)
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var (
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bits int
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pkcs1 bool
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)
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// Register the "keygen" subcommand.
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func Register(root *cobra.Command) {
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cmd := &cobra.Command{
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Use: "keygen",
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Short: "Generate a new private key and save to file",
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Run: Keygen,
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Args: cobra.ExactArgs(1),
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}
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cmd.Flags().IntVarP(&bits, "bits", "b", 3072, "Key size in bits")
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cmd.Flags().BoolVarP(&pkcs1, "pkcs1", "", false, "Write key as PKCS#1 rather than PKCS#8")
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root.AddCommand(cmd)
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}
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// Keygen will generate a new RSA private key and save it to a file.
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func Keygen(cmd *cobra.Command, args []string) {
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filename := args[0]
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key, err := rsa.GenerateKey(rand.Reader, bits)
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if err != nil {
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fmt.Fprintf(os.Stderr, "Failed to generate new key (%d bits): %v\n", bits, err)
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os.Exit(1)
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}
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// prepare DER-form data
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var der []byte
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if pkcs1 {
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der = x509.MarshalPKCS1PrivateKey(key)
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} else {
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der, err = x509.MarshalPKCS8PrivateKey(key)
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if err != nil {
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fmt.Fprintf(os.Stderr, "Failed to marshal PKCS#8 private key: %v\n", err)
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os.Exit(1)
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}
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}
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// prepare PEM-form data
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typ := pemfile.TypePKCS8PrivateKey
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if pkcs1 {
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typ = pemfile.TypePKCS1PrivateKey
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}
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x509raw := pem.EncodeToMemory(&pem.Block{
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Type: typ,
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Bytes: der,
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})
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// write to file
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if err := os.WriteFile(filename, x509raw, 0600); err != nil {
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fmt.Fprintln(os.Stderr, err)
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os.Exit(1)
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}
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}
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