57 lines
1.1 KiB
Go
57 lines
1.1 KiB
Go
package shared
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import (
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"crypto/subtle"
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"encoding/base64"
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"errors"
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"github.com/dchest/siphash"
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"gopkg.in/mgo.v2/bson"
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"os"
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)
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var idHashKey []byte = []byte("semi-private-key")
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func exists(name string) bool {
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if _, err := os.Stat(name); err != nil {
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if os.IsNotExist(err) {
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return false
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}
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}
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return true
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}
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func validateId(id []byte) error {
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if len(id) != 16 {
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return errors.New("valid ids are 16 bytes (126 bit) long.")
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}
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h := siphash.New(idHashKey)
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h.Write(id[4:16])
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if subtle.ConstantTimeCompare(h.Sum(nil)[0:4], id[0:4]) != 1 {
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return errors.New("invalid id checksum")
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}
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return nil
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}
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func ObjectIdToPublicId(id bson.ObjectId) string {
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if id == "" {
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return ""
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}
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h := siphash.New(idHashKey)
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h.Write([]byte(id))
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return base64.URLEncoding.EncodeToString(append(h.Sum(nil)[0:4], []byte(id)...))
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}
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func PublicIdToObjectId(id string) (bson.ObjectId, error) {
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if id == "" {
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return "", nil
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}
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cypher, err := base64.URLEncoding.DecodeString(id)
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if err != nil {
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return "", err
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}
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if err := validateId(cypher); err != nil {
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return "", err
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}
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return bson.ObjectId(cypher[4:16]), nil
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}
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