91 lines
1.7 KiB
Go
91 lines
1.7 KiB
Go
package twofactor
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import (
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"crypto/rand"
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"errors"
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"fmt"
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"hash"
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"net/url"
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)
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type Type uint
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const (
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OATH_HOTP = iota
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OATH_TOTP
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)
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// PRNG is an io.Reader that provides a cryptographically secure
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// random byte stream.
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var PRNG = rand.Reader
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var (
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ErrInvalidURL = errors.New("twofactor: invalid URL")
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ErrInvalidAlgo = errors.New("twofactor: invalid algorithm")
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)
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// Type OTP represents a one-time password token -- whether a
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// software taken (as in the case of Google Authenticator) or a
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// hardware token (as in the case of a YubiKey).
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type OTP interface {
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// Returns the current counter value; the meaning of the
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// returned value is algorithm-specific.
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Counter() uint64
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// Set the counter to a specific value.
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SetCounter(uint64)
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// the secret key contained in the OTP
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Key() []byte
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// generate a new OTP
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OTP() string
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// the output size of the OTP
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Size() int
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// the hash function used by the OTP
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Hash() func() hash.Hash
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// URL generates a Google Authenticator url (or perhaps some other url)
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URL(string) string
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// QR outputs a byte slice containing a PNG-encoded QR code
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// of the URL.
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QR(string) ([]byte, error)
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// Returns the type of this OTP.
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Type() Type
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}
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func OTPString(otp OTP) string {
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var typeName string
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switch otp.Type() {
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case OATH_HOTP:
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typeName = "OATH-HOTP"
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case OATH_TOTP:
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typeName = "OATH-TOTP"
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}
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return fmt.Sprintf("%s, %d", typeName, otp.Size())
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}
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func FromURL(URL string) (OTP, string, error) {
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u, err := url.Parse(URL)
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if err != nil {
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return nil, "", err
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}
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if u.Scheme != "otpauth" {
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return nil, "", ErrInvalidURL
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}
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switch {
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case u.Host == "totp":
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return totpFromURL(u)
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case u.Host == "hotp":
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return hotpFromURL(u)
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default:
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return nil, "", ErrInvalidURL
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}
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}
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