89 lines
1.4 KiB
Go
89 lines
1.4 KiB
Go
package golicense
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import (
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"crypto/hmac"
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"crypto/sha256"
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"encoding/base64"
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"encoding/json"
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"errors"
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"time"
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)
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var (
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secret = []byte("superDuperSecret123!")
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ErrorHmacMismatch = errors.New("checksum mismatch - not a valid license key")
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)
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type Data struct {
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Feature1 bool
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Feature2 int
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ValidTill time.Time
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CreatedAt time.Time
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}
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type Envelope struct {
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Data Data
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Checksum []byte
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}
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func (e *Envelope) String() (string, error) {
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d, err := json.Marshal(e)
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if err != nil {
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return "", err
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}
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str := base64.StdEncoding.EncodeToString(d)
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return str, nil
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}
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func New(feature1 bool, feature2 int, expire int) (*Envelope, error) {
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d := Data{
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Feature1: feature1,
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Feature2: feature2,
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ValidTill: time.Now().AddDate(0, 0, expire),
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}
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e := Envelope{
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Data: d,
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}
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db, err := json.Marshal(&d)
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if err != nil {
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return nil, err
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}
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hmac := hmac.New(sha256.New, secret)
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hmac.Write(db)
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dh := hmac.Sum(nil)
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e.Checksum = dh
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return &e, nil
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}
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func Verify(in string) (*Envelope, error) {
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d, err := base64.StdEncoding.DecodeString(in)
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if err != nil {
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return nil, err
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}
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var e Envelope
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if err := json.Unmarshal(d, &e); err != nil {
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return nil, err
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}
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db, err := json.Marshal(e.Data)
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if err != nil {
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return nil, err
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}
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hm := hmac.New(sha256.New, secret)
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hm.Write(db)
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dh := hm.Sum(nil)
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if !hmac.Equal(e.Checksum, dh) {
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return nil, ErrorHmacMismatch
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}
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return &e, nil
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}
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