aboutsummaryrefslogtreecommitdiff
path: root/ask/ask.go
blob: f021ffdeb4e2dba8c4517b2d91764021ba478999 (plain)
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
// Package ask implements interactive password retrieval
package ask

import (
	"errors"
	"io"
	"os"

	"dim13.org/signify/bhash"

	"golang.org/x/crypto/ssh/terminal"
)

var (
	ErrNoPassword = errors.New("please provide a password")
	ErrNoMatch    = errors.New("passwords don't match")
)

const (
	promtPassphrase = "passphrase: "
	promtConfirmed  = "confirm passphrase: "
)

type Passphrase struct{}

func (Passphrase) Derive(salt []byte, rounds int, length int) ([]byte, error) {
	pass, err := passphrase()
	if err != nil {
		return nil, err
	}
	return bhash.Pbkdf([]byte(pass), salt, rounds, length)
}

type Confirmed struct{}

func (Confirmed) Derive(salt []byte, rounds int, length int) ([]byte, error) {
	pass, err := confirmed()
	if err != nil {
		return nil, err
	}
	return bhash.Pbkdf([]byte(pass), salt, rounds, length)
}

// confirmed asks for password twice
func confirmed() (string, error) {
	restore, err := makeRaw(os.Stdin)
	if err != nil {
		return "", err
	}
	defer restore()
	pass, err := readPassword(os.Stdin, promtPassphrase)
	if err != nil {
		return "", err
	}
	pass2, err := readPassword(os.Stdin, promtConfirmed)
	if err != nil {
		return "", err
	}
	if pass != pass2 {
		return "", ErrNoMatch
	}
	return pass, nil
}

// passphrase asks for passphrase once
func passphrase() (string, error) {
	restore, err := makeRaw(os.Stdin)
	if err != nil {
		return "", err
	}
	defer restore()
	return readPassword(os.Stdin, promtPassphrase)
}

func readPassword(rw io.ReadWriter, prompt string) (string, error) {
	pass, err := terminal.NewTerminal(rw, "").ReadPassword(prompt)
	if err != nil {
		return "", err
	}
	if len(pass) == 0 {
		return "", ErrNoPassword
	}
	return pass, nil
}

func makeRaw(f *os.File) (func(), error) {
	fd := int(f.Fd())
	oldState, err := terminal.MakeRaw(fd)
	if err != nil {
		return nil, err
	}
	return func() { terminal.Restore(fd, oldState) }, nil
}