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path: root/verify.go
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package main

import (
	"errors"
	"flag"
	"fmt"
	"io/ioutil"

	"dim13.org/signify/file"
	"dim13.org/signify/key"
)

// Usage: signify -V [-eqz] [-p pubkey] [-t keytype] [-x sigfile] -m message

func verify(args []string) error {
	opts := flag.NewFlagSet("verify", flag.ExitOnError)
	var (
		embedded = *opts.Bool("e", false, "Embed message")
		quiet    = *opts.Bool("q", false, "Quiet mode")
		zip      = *opts.Bool("z", false, "Verify gzip archive") // TODO
		pubFile  = *opts.String("p", "", "Public key file")
		keyType  = *opts.String("t", "", "Key type") // TODO
		sigFile  = *opts.String("x", "", "Signature file")
		msgFile  = *opts.String("m", "", "Message file (required)")
	)
	opts.Parse(args)
	if embedded && zip {
		return errors.New("can't combine -e and -z options")
	}
	if msgFile == "" {
		opts.Usage()
		return nil
	}
	if sigFile == "" {
		sigFile = file.SigName(msgFile)
	}
	_ = keyType // TODO

	sig, msg, verifyWith, err := OpenSig(sigFile)
	if err != nil {
		return err
	}
	if pubFile == "" {
		pubFile = verifyWith
	}
	pubKey, err := OpenPub(pubFile)
	if err != nil {
		return err
	}
	if !embedded {
		msg, err = ioutil.ReadFile(msgFile)
		if err != nil {
			return err
		}
	}
	if err := pubKey.Verify(msg, sig); err != nil {
		return err
	}
	if !quiet {
		fmt.Println("Signature Verified")
	}
	return nil
}

func OpenPub(fname string) (*key.Pub, error) {
	block, err := file.DecodeFile(fname)
	if err != nil {
		return nil, err
	}
	pubKey := new(key.Pub)
	if err := key.Unmarshal(block.Bytes, pubKey); err != nil {
		return nil, err
	}
	if err := pubKey.Check(); err != nil {
		return nil, err
	}
	return pubKey, nil
}

func OpenSig(fname string) (*key.Sig, []byte, string, error) {
	block, err := file.DecodeFile(fname)
	if err != nil {
		return nil, nil, "", err
	}
	sig := new(key.Sig)
	if err := key.Unmarshal(block.Bytes, sig); err != nil {
		return nil, nil, "", err
	}
	if err := sig.Check(); err != nil {
		return nil, nil, "", err
	}
	pubKey, _ := file.PubFile(block.Comment)
	return sig, block.Message, pubKey, nil
}