forked from balena-os/librsync-go
/
signature.go
98 lines (82 loc) · 2 KB
/
signature.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
package librsync
import (
"encoding/binary"
"fmt"
"io"
"golang.org/x/crypto/blake2b"
"golang.org/x/crypto/md4"
)
const (
BLAKE2_SUM_LENGTH = 32
MD4_SUM_LENGTH = 16
)
type SignatureType struct {
sigType MagicNumber
blockLen uint32
strongLen uint32
strongSigs [][]byte
weak2block map[uint32]int
}
func CalcStrongSum(data []byte, sigType MagicNumber, strongLen uint32) ([]byte, error) {
switch sigType {
case BLAKE2_SIG_MAGIC:
d := blake2b.Sum256(data)
return d[:strongLen], nil
case MD4_SIG_MAGIC:
d := md4.New()
d.Write(data)
return d.Sum(nil)[:strongLen], nil
}
return nil, fmt.Errorf("Invalid sigType %#x", sigType)
}
func Signature(input io.Reader, output io.Writer, blockLen, strongLen uint32, sigType MagicNumber) (*SignatureType, error) {
var maxStrongLen uint32
switch sigType {
case BLAKE2_SIG_MAGIC:
maxStrongLen = BLAKE2_SUM_LENGTH
case MD4_SIG_MAGIC:
maxStrongLen = MD4_SUM_LENGTH
default:
return nil, fmt.Errorf("invalid sigType %#x", sigType)
}
if strongLen > maxStrongLen {
return nil, fmt.Errorf("invalid strongLen %d for sigType %#x", strongLen, sigType)
}
err := binary.Write(output, binary.BigEndian, sigType)
if err != nil {
return nil, err
}
err = binary.Write(output, binary.BigEndian, blockLen)
if err != nil {
return nil, err
}
err = binary.Write(output, binary.BigEndian, strongLen)
if err != nil {
return nil, err
}
block := make([]byte, blockLen)
var ret SignatureType
ret.weak2block = make(map[uint32]int)
ret.sigType = sigType
ret.strongLen = strongLen
ret.blockLen = blockLen
for {
n, err := input.Read(block)
if err == io.EOF {
break
} else if err != nil {
return nil, err
}
data := block[:n]
weak := WeakChecksum(data)
err = binary.Write(output, binary.BigEndian, weak)
if err != nil {
return nil, err
}
strong, _ := CalcStrongSum(data, sigType, strongLen)
output.Write(strong)
ret.weak2block[weak] = len(ret.strongSigs)
ret.strongSigs = append(ret.strongSigs, strong)
}
return &ret, nil
}