diff --git a/client/client.go b/client/client.go
index e69f3534bb520b0fd6ea8ddecd14db58ea8e436b..b13c4cbdd9c5ad88246f741077df7d704b298b27 100644
--- a/client/client.go
+++ b/client/client.go
@@ -79,11 +79,8 @@ func Sign(pub ssh.PublicKey, token string, conf *Config) (*ssh.Certificate, erro
 	if err != nil {
 		return nil, err
 	}
-	marshaled := ssh.MarshalAuthorizedKey(pub)
-	// Remove the trailing newline.
-	marshaled = marshaled[:len(marshaled)-1]
 	s, err := json.Marshal(&lib.SignRequest{
-		Key:        string(marshaled),
+		Key:        lib.GetPublicKey(pub),
 		ValidUntil: time.Now().Add(validity),
 	})
 	if err != nil {
diff --git a/cmd/cashierd/main.go b/cmd/cashierd/main.go
index 31ee240b54317d664e3a0e8a34d4191f8476de5d..52b6a8b9548bb6cc15978a64831c4d8c47522b76 100644
--- a/cmd/cashierd/main.go
+++ b/cmd/cashierd/main.go
@@ -34,7 +34,6 @@ import (
 	"github.com/nsheridan/cashier/server/static"
 	"github.com/nsheridan/cashier/server/store"
 	"github.com/nsheridan/cashier/server/templates"
-	"github.com/nsheridan/cashier/server/util"
 	"github.com/nsheridan/cashier/server/wkfs/vaultfs"
 	"github.com/nsheridan/wkfs/s3"
 	"github.com/sid77/drop"
@@ -169,7 +168,7 @@ func signHandler(a *appContext, w http.ResponseWriter, r *http.Request) (int, er
 	}
 	json.NewEncoder(w).Encode(&lib.SignResponse{
 		Status:   "ok",
-		Response: util.GetPublicKey(cert),
+		Response: lib.GetPublicKey(cert),
 	})
 	return http.StatusOK, nil
 }
diff --git a/lib/const.go b/lib/proto.go
similarity index 59%
rename from lib/const.go
rename to lib/proto.go
index 1ba274931d7ffa6ea59b67d8683f3c3d8b4e925c..f3d7115605265e9a789d72a911f393c4ab7a3a2f 100644
--- a/lib/const.go
+++ b/lib/proto.go
@@ -9,9 +9,7 @@ type SignRequest struct {
 }
 
 // SignResponse is sent by the server.
-// `Status' is "ok" or "error".
-// `Response' contains a signed certificate or an error message.
 type SignResponse struct {
-	Status   string `json:"status"`
-	Response string `json:"response"`
+	Status   string `json:"status"`   // Status will be "ok" or "error".
+	Response string `json:"response"` // Response will contain either the signed certificate or the error message.
 }
diff --git a/server/util/util.go b/lib/util.go
similarity index 60%
rename from server/util/util.go
rename to lib/util.go
index 10f5eca6e3152e51dcc2b9ef3cd94c9d77c38b9e..b1c7b87016343712bcbbb534cfbecef733a083e6 100644
--- a/server/util/util.go
+++ b/lib/util.go
@@ -1,10 +1,10 @@
-package util
+package lib
 
 import "golang.org/x/crypto/ssh"
 
 // GetPublicKey marshals a ssh certificate to a string.
-func GetPublicKey(cert *ssh.Certificate) string {
-	marshaled := ssh.MarshalAuthorizedKey(cert)
+func GetPublicKey(pub ssh.PublicKey) string {
+	marshaled := ssh.MarshalAuthorizedKey(pub)
 	// Strip trailing newline
 	return string(marshaled[:len(marshaled)-1])
 }
diff --git a/server/util/util_test.go b/lib/util_test.go
similarity index 95%
rename from server/util/util_test.go
rename to lib/util_test.go
index d294d86d2ec1b20a7bf5410a347a48c974e1960f..9e89297073d63f53c2b2f5110b53efce22b0c485 100644
--- a/server/util/util_test.go
+++ b/lib/util_test.go
@@ -1,4 +1,4 @@
-package util
+package lib
 
 import (
 	"testing"
diff --git a/server/store/store.go b/server/store/store.go
index a447e726b3821e73d9de3db2f9fe52493768c15c..8af77e330618554fee94580daed704aa87c6c7cb 100644
--- a/server/store/store.go
+++ b/server/store/store.go
@@ -5,8 +5,8 @@ import (
 
 	"golang.org/x/crypto/ssh"
 
+	"github.com/nsheridan/cashier/lib"
 	"github.com/nsheridan/cashier/server/config"
-	"github.com/nsheridan/cashier/server/util"
 )
 
 // New returns a new configured database.
@@ -54,6 +54,6 @@ func parseCertificate(cert *ssh.Certificate) *CertRecord {
 		Principals: cert.ValidPrincipals,
 		CreatedAt:  parseTime(cert.ValidAfter),
 		Expires:    parseTime(cert.ValidBefore),
-		Raw:        util.GetPublicKey(cert),
+		Raw:        lib.GetPublicKey(cert),
 	}
 }