/
ecdsa.go
224 lines (200 loc) · 4.26 KB
/
ecdsa.go
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package main
import (
"bufio"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/md5"
"crypto/rand"
"crypto/sha1"
"crypto/sha256"
"crypto/sha512"
"encoding/hex"
"flag"
"fmt"
"hash"
"hash/adler32"
"hash/crc32"
"hash/crc64"
"hash/fnv"
"io"
"log"
"math/big"
"os"
"strings"
)
func main() {
log.SetFlags(0)
log.SetPrefix("ecdsa: ")
var h, c string
var p bool
flag.Usage = usage
flag.StringVar(&h, "h", "sha512", "use hash")
flag.StringVar(&c, "c", "P521", "use curve")
flag.BoolVar(&p, "p", true, "print private keys/hash when signing")
flag.Bool("s", false, "sign file")
flag.Bool("v", false, "verify file")
flag.Parse()
var mode uint
flag.Visit(func(f *flag.Flag) {
switch f.Name {
case "s":
mode |= 1
case "v":
mode |= 2
}
})
switch mode {
case 1:
if flag.NArg() < 1 {
usage()
}
ck(sign(flag.Arg(0), p, makeHash(h), makeCurve(c)))
case 2:
if flag.NArg() < 2 {
usage()
}
ck(verify(flag.Arg(0), flag.Arg(1), makeHash(h), makeCurve(c)))
default:
usage()
}
}
func ck(err error) {
if err != nil {
log.Fatal(err)
}
}
func usage() {
fmt.Fprintln(os.Stderr, "usage: ecdsa [options] -s <file>")
fmt.Fprintln(os.Stderr, " ecdsa [options] -v <key> <file>")
flag.PrintDefaults()
fmt.Fprintln(os.Stderr, "")
fmt.Fprintln(os.Stderr, "valid curves: P224 P256 P384 P521")
fmt.Fprintln(os.Stderr, "valid hash: md5 sha1 sha256 sha384 sha512 sha512-224 sha512-256 crc32-ieee crc64-iso")
fmt.Fprintln(os.Stderr, " crc64-ecma adler32 fnv32 fnv32a fnv64 fnv64a")
os.Exit(2)
}
func sign(name string, priv bool, h hash.Hash, c elliptic.Curve) error {
m, err := sum(name, h)
if err != nil {
return err
}
p, err := ecdsa.GenerateKey(c, rand.Reader)
if err != nil {
return err
}
r, s, err := ecdsa.Sign(rand.Reader, p, m)
if err != nil {
return err
}
w := os.Stdout
if priv {
fmt.Fprintf(w, "d=%v\n", p.D)
fmt.Fprintf(w, "h=%v\n", hex.EncodeToString(m))
}
fmt.Fprintf(w, "x=%v\n", p.X)
fmt.Fprintf(w, "y=%v\n", p.Y)
fmt.Fprintf(w, "r=%v\n", r)
fmt.Fprintf(w, "s=%v\n", s)
return nil
}
func verify(key, name string, h hash.Hash, c elliptic.Curve) error {
m, err := sum(name, h)
if err != nil {
return err
}
f, err := os.Open(key)
if err != nil {
return err
}
defer f.Close()
X := new(big.Int)
Y := new(big.Int)
R := new(big.Int)
S := new(big.Int)
s := bufio.NewScanner(f)
for s.Scan() {
t := s.Text()
n, _ := fmt.Sscanf(t, "x=%v", X)
if n == 1 {
continue
}
n, _ = fmt.Sscanf(t, "y=%v", Y)
if n == 1 {
continue
}
n, _ = fmt.Sscanf(t, "r=%v", R)
if n == 1 {
continue
}
fmt.Sscanf(t, "s=%v", S)
}
p := &ecdsa.PublicKey{c, X, Y}
v := ecdsa.Verify(p, m, R, S)
if !v {
fmt.Printf("ECDSA verification failed for file %q\n", name)
} else {
fmt.Printf("ECDSA verification succeeded for file %q\n", name)
}
return nil
}
func sum(name string, h hash.Hash) ([]byte, error) {
f, err := os.Open(name)
if err != nil {
return nil, err
}
defer f.Close()
b := bufio.NewReader(f)
io.Copy(h, b)
m := h.Sum(nil)
return m, nil
}
func makeHash(name string) hash.Hash {
switch strings.ToLower(name) {
case "md5":
return md5.New()
case "sha1":
return sha1.New()
case "sha256":
return sha256.New()
case "sha384":
return sha512.New384()
case "sha512":
return sha512.New()
case "sha512-224":
return sha512.New512_224()
case "sha512-256":
return sha512.New512_256()
case "crc32-ieee":
return crc32.NewIEEE()
case "crc64-iso":
return crc64.New(crc64.MakeTable(crc64.ISO))
case "crc64-ecma":
return crc64.New(crc64.MakeTable(crc64.ECMA))
case "adler32":
return adler32.New()
case "fnv32":
return fnv.New32()
case "fnv32a":
return fnv.New32a()
case "fnv64":
return fnv.New64()
case "fnv64a":
return fnv.New64a()
}
log.Fatalf("unknown hash %q", name)
return nil
}
func makeCurve(name string) elliptic.Curve {
switch name {
case "P224":
return elliptic.P224()
case "P256":
return elliptic.P256()
case "P384":
return elliptic.P384()
case "P521":
return elliptic.P521()
}
log.Fatalf("unknown curve %q", name)
return nil
}