Example #1
0
//Verify checks res is codeward in the server.
func Verify(res []byte, fnum int, key []byte, n int, loc []int) (bool, error) {
	p := &prf{key: key, fnum: fnum}
	for _, l := range loc {
		res[len(res)-1] ^= p.rand(l)
	}
	enc, err := reedsolomon.NewAN(nServerBlock-1, 1, p.perm())
	if err != nil {
		log.Println(err)
		return false, err
	}
	data := make([][]byte, nServerBlock)
	for i := 0; i < nServerBlock; i++ {
		data[i] = make([]byte, 1)
		data[i][0] = res[i]
	}
	ok, err := enc.Verify(data)
	if err != nil {
		log.Println(err)
		return false, err
	}
	return ok, nil
}
Example #2
0
//Build builds shards for servers with reed solomon coding
//and (255,1) redundant codes for each servers for challenge/response.
func Build(m, n int, fname string) ([]string, []byte, error) {
	key := make([]byte, 32)
	if _, err := rand.Read(key); err != nil {
		log.Fatal(err)
	}
	prf := &prf{key: key}

	enc, err := reedsolomon.New(n, m)
	if err != nil {
		log.Println(err)
		return nil, nil, err
	}
	data := make([][]byte, m+n)

	rs, err := rmmap(fname)
	if err != nil {
		log.Println(err)
		return nil, nil, err
	}
	defer rs.Close()

	shardSize, err := size(rs.f, n)
	if err != nil {
		return nil, nil, err
	}
	serverBlockSize := blocks(shardSize, nServerBlock-1)

	ss := make([]*smap, m+n)
	name := parseName(fname)
	outfiles := make([]string, m+n)
	for i := 0; i < m+n; i++ {
		outfiles[i] = name.rename(i)
		ss[i], err = wmmap(outfiles[i], int64(serverBlockSize)*nServerBlock)
		if err != nil {
			log.Println(err)
			return nil, nil, err
		}
		data[i] = ss[i].bytes()[:shardSize]
	}
	defer func() {
		for i := 0; i < m+n; i++ {
			ss[i].Close()
		}
	}()
	for i := 0; i < n; i++ {
		end := (i + 1) * shardSize
		if end > len(rs.bytes()) {
			end = len(rs.bytes())
		}
		copy(data[i], rs.bytes()[i*shardSize:end])
	}
	if err != nil {
		log.Println(err)
		return nil, nil, err
	}

	if err = enc.Encode(data); err != nil {
		log.Println(err)
		return nil, nil, err
	}
	encServer, err := reedsolomon.NewAN(nServerBlock-1, 1, prf.perm())
	if err != nil {
		log.Println(err)
		return nil, nil, err
	}
	for i := 0; i < m+n; i++ {
		prf.fnum = i
		if err := serverEncode(ss[i].bytes(), prf, serverBlockSize, encServer); err != nil {
			log.Println(err)
			return nil, nil, err
		}
	}
	return outfiles, key, err
}