270 lines
6.6 KiB
Go
270 lines
6.6 KiB
Go
// sigtool.go -- Tool to generate, manage Ed25519 keys and
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// signatures.
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//
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// (c) 2016 Sudhi Herle <sudhi@herle.net>
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//
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// Licensing Terms: GPLv2
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//
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// If you need a commercial license for this work, please contact
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// the author.
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//
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// This software does not come with any express or implied
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// warranty; it is provided "as is". No claim is made to its
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// suitability for any purpose.
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package main
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import (
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"os"
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"io"
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"fmt"
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"path"
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// Our pkg
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"github.com/opencoff/go-lib/options"
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"github.com/opencoff/go-lib/sign"
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)
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// This will be filled in by "build"
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var Version string = "1.0"
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var Z string = path.Base(os.Args[0])
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// die with error
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func die(f string, v ...interface{}) {
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z := fmt.Sprintf("%s: %s", Z, f)
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s := fmt.Sprintf(z, v...)
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if n := len(s); s[n-1] != '\n' { s += "\n" }
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os.Stderr.WriteString(s)
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os.Exit(1)
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}
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// Option parsing spec for the main program
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var Maindesc = fmt.Sprintf(`
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Usage: %s [options] command [options ..] [args ..]
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%s is a tool to generate, sign and verify files with Ed25519 signatures.
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--
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# Options
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help -h,--help Show this help message and exit
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ver -v,--version Show version info and exit
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--
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--
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# Commands
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gen generate,gen Generate a new Ed25519 keypair
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sign sign, s Sign a file with a private key
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verify verify, v Verify a signature against a file and public key
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--`, Z, Z)
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// Option parsing spec for key gen
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var Gendesc = fmt.Sprintf(`
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Usage: %s generate [options] path-prefix
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Generate a new Ed25519 public/private key pair. The public key is written
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to PATH-PREFIX.pub and private key to PATH-PREFIX.key.
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--
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# Options
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help -h,--help Show this help message and exit
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pw -p,--passwd Ask for a passphrase to encrypt the private key
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comment= -c=,--comment= Use 'C' as the text comment for the keys []
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envpw= -e=E,--env-pass=E Use passphrase from environment var E []
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--
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--
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*
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--`, Z)
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// Option parsing spec for signing a file
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var Signdesc = fmt.Sprintf(`
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Usage: %s sign [options] privkey file
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Sign FILE with an Ed25519 PRIVKEY and write the signature to STDOUT.
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--
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# Options
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help -h,--help Show this help message and exit
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pw -p,--passwd Ask for a passphrase to decrypt the private key
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envpw= -e=E,--env-pass=E Use passphrase from environment var E []
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output=- -o=F,--output=F Write signature to file F [STDOUT]
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--
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--
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*
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--`, Z)
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// Option parsing spec for signature verification
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var Verifydesc = fmt.Sprintf(`
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Usage: %s verify [options] pubkey sig file
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Verify signature SIG of FILE using Ed25519 public key in PUBKEY.
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--
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# Options
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help -h,--help Show this help message and exit
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quiet -q,--quiet Don't show any output, exit with status code
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--
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--
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*
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--`, Z)
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// Run the generate command
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func gen(s *options.Spec, opt *options.Options) {
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if opt.GetBool("help") {
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s.PrintUsageAndExit()
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}
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if len(opt.Args) < 1 {
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s.PrintUsageWithError(fmt.Errorf("Missing path-prefix."))
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}
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var pw string
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var comm string
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var err error
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if pwenv, ok := opt.Get("envpw"); ok {
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pw = os.Getenv(pwenv)
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} else if opt.GetBool("pw") {
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pw, err = sign.Askpass("Enter passphrase for private key", true)
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if err != nil { die("%s: %s", Z, err) }
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}
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comm, _ = opt.Get("comment")
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kp, err := sign.NewKeypair()
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if err != nil { die("%s: %s", Z, err) }
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bn := opt.Args[0]
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err = kp.Serialize(bn, comm, pw)
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if err != nil { die("%s: %s", Z, err) }
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}
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// Run the 'sign' command.
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func signify(s *options.Spec, opt *options.Options) {
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if opt.GetBool("help") {
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s.PrintUsageAndExit()
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}
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if len(opt.Args) < 2 {
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s.PrintUsageWithError(fmt.Errorf("Missing arguments (key? file?)"))
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}
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var pw string
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var err error
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var fd io.Writer = os.Stdout
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if pwenv, ok := opt.Get("envpw"); ok {
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pw = os.Getenv(pwenv)
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} else if opt.GetBool("pw") {
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pw, err = sign.Askpass("Enter passphrase for private key", false)
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if err != nil { die("%s: %s", Z, err) }
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}
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if outf, ok := opt.Get("output"); ok {
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if outf != "-" {
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fdx, err := os.OpenFile(outf, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0644)
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if err != nil { die("%s: Can't create output file %s: %s", Z, outf, err) }
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defer fdx.Close()
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fd = fdx
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}
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}
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kn := opt.Args[0]
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fn := opt.Args[1]
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pk, err := sign.ReadPrivateKey(kn, pw)
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if err != nil { die("%s: %s", Z, err) }
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sig, err := pk.SignFile(fn)
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if err != nil { die("%s: %s", Z, err) }
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sigo, err := sig.Serialize(fmt.Sprintf("inpfile=%s", fn))
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fd.Write(sigo)
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}
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// Verify signature on a given file
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func verify(s *options.Spec, opt *options.Options) {
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if opt.GetBool("help") {
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s.PrintUsageAndExit()
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}
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if len(opt.Args) < 3 {
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s.PrintUsageWithError(fmt.Errorf("Missing arguments (key? file? pubkey?)"))
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}
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pn := opt.Args[0]
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sn := opt.Args[1]
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fn := opt.Args[2]
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sig, err := sign.ReadSignature(sn)
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if err != nil { die("%s: Can't read signature %s: %s", Z, sn, err) }
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pk, err := sign.ReadPublicKey(pn)
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if err != nil { die("%s: %s", Z, err) }
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ok, err := pk.VerifyFile(fn, sig)
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if err != nil { die("%s: %s", Z, err) }
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exit := 0
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if !ok { exit = 1 }
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if !opt.GetBool("quiet") {
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if ok {
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fmt.Printf("%s: Signature %s verified\n", fn, sn)
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} else {
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fmt.Printf("%s: Signature %s verification FAILURE\n", fn, sn)
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}
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}
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os.Exit(exit)
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}
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func main() {
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var env = []string{}
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spec := options.MustParse(Maindesc)
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gspec := options.MustParse(Gendesc)
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sspec := options.MustParse(Signdesc)
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vspec := options.MustParse(Verifydesc)
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opts, err := spec.Interpret(os.Args, env)
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if err != nil { die("%s", err) }
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if opts.GetBool("help") { spec.PrintUsageAndExit() }
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if opts.GetBool("ver") {
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fmt.Printf("%s: %s\n", Z, Version)
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os.Exit(0)
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}
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switch opts.Command {
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case "gen":
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o, err := gspec.Interpret(opts.Args, env)
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if err != nil { die("%s", err) }
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gen(gspec, o)
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case "sign":
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ox, err := sspec.Interpret(opts.Args, env)
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if err != nil { die("%s", err) }
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signify(sspec, ox)
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case "verify":
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ox, err := vspec.Interpret(opts.Args, env)
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if err != nil { die("%s", err) }
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verify(vspec, ox)
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default:
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die("%s: Forgot to add code for command %s", Z, opts.Command)
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}
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}
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// vim: ft=go:sw=4:ts=4:expandtab:tw=78:
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