diff --git a/pkg/captcha/db.go b/pkg/captcha/db.go
index 758125e..b9fa5e7 100644
--- a/pkg/captcha/db.go
+++ b/pkg/captcha/db.go
@@ -9,9 +9,21 @@ import (
 	"time"
 )
 
+var expiredScanInterval = 60 * time.Second
+
 type ID string
 
-var expiredScanInterval = 60 * time.Second
+// NewID generates an ID as a sha256 hash of additionalData, current time
+// and answer encoded with base64 in raw URL variant.
+func NewID(additionalData string, answer Answer) ID {
+	idHash := sha256.New()
+
+	idHash.Write([]byte(additionalData))
+	idHash.Write([]byte(strconv.FormatInt(time.Now().UnixMicro(), 16)))
+	idHash.Write([]byte(answer))
+
+	return ID(base64.RawURLEncoding.EncodeToString(idHash.Sum(nil)))
+}
 
 type ICaptchaDB interface {
 	New(data string) (ICaptcha, ID)
@@ -54,13 +66,7 @@ func (cdb *CaptchaDB) SetExpiry(expire time.Duration) {
 // `data` string is an additional random data used to generate an ID,
 // e.g. IP-address.
 func (cdb *CaptchaDB) New(data string, captcha ICaptcha) (ICaptcha, ID) {
-	idHash := sha256.New()
-
-	idHash.Write([]byte(data))
-	idHash.Write([]byte(strconv.FormatInt(time.Now().UnixMicro(), 16)))
-	idHash.Write([]byte(captcha.GetAnswer()))
-
-	id := ID(base64.RawURLEncoding.EncodeToString(idHash.Sum(nil)))
+	id := NewID(data, captcha.GetAnswer())
 
 	cdb.mut.Lock()
 	defer cdb.mut.Unlock()