diff --git a/core/auth/auth.go b/core/auth/auth.go
index 68a49a0..46779f4 100644
--- a/core/auth/auth.go
+++ b/core/auth/auth.go
@@ -14,6 +14,22 @@ type AuthService struct {
 	bcrypt util.Bcrypt
 }
 
+// AuthRepository interface for dependency injection
+type AuthRepository interface {
+	GetVerifiedUserByEmail(string) (*types.User, error)
+	GetUserByActiveSession(string) (*types.User, error)
+	GetUserByApiKey(string) (*types.User, error)
+	GetUserByEmailVerifyCode(string) (*types.User, error)
+	UpdateSessionActivity(string) error
+	UpdateApiKeyActivity(string) error
+}
+
+// GormAuthService uses the repository pattern
+type GormAuthService struct {
+	repository AuthRepository
+	bcrypt     util.Bcrypt
+}
+
 type Interface interface {
 	Authenticate(string, string) (*types.User, error)
 	AuthenticateUser(email string, password string) (*types.User, error)
@@ -28,6 +44,12 @@ func NewAuthService(db db.Datastore, bcrypt util.Bcrypt) *AuthService {
 	return authService
 }
 
+func NewGormAuthService(repository AuthRepository, bcrypt util.Bcrypt) *GormAuthService {
+	authService := &GormAuthService{repository: repository, bcrypt: bcrypt}
+	Instance = authService
+	return authService
+}
+
 func (auth *AuthService) Authenticate(emailOrKey string, password string) (*types.User, error) {
 	// authenticate via session, apikey or user
 	user, err := auth.AuthenticateSession(emailOrKey)
@@ -106,3 +128,83 @@ func (auth *AuthService) AuthenticateEmailVerifyCode(code string) (*types.User,
 
 	return u, nil
 }
+
+// GormAuthService implementations
+func (auth *GormAuthService) Authenticate(emailOrKey string, password string) (*types.User, error) {
+	// authenticate via session, apikey or user
+	user, err := auth.AuthenticateSession(emailOrKey)
+
+	if err == nil {
+		return user, nil
+	}
+
+	user, err = auth.AuthenticateApiKey(emailOrKey)
+
+	if err == nil {
+		return user, nil
+	}
+
+	user, err = auth.AuthenticateUser(emailOrKey, password)
+
+	if err == nil {
+		return user, nil
+	}
+
+	user, err = auth.AuthenticateEmailVerifyCode(emailOrKey)
+
+	if err == nil {
+		return user, nil
+	}
+
+	return nil, errors.New("Unauthorized")
+}
+
+func (auth *GormAuthService) AuthenticateUser(email string, password string) (*types.User, error) {
+	u, err := auth.repository.GetVerifiedUserByEmail(email)
+
+	if err != nil {
+		return nil, errors.New("Invalid email or password")
+	}
+
+	err = auth.bcrypt.CompareHashAndPassword([]byte(u.PasswordHash), []byte(password))
+
+	if err != nil {
+		return nil, errors.New("Invalid email or password")
+	}
+
+	return u, nil
+}
+
+func (auth *GormAuthService) AuthenticateSession(id string) (*types.User, error) {
+	u, err := auth.repository.GetUserByActiveSession(id)
+
+	if err != nil {
+		return nil, errors.New("Invalid session")
+	}
+
+	auth.repository.UpdateSessionActivity(id)
+
+	return u, nil
+}
+
+func (auth *GormAuthService) AuthenticateApiKey(id string) (*types.User, error) {
+	u, err := auth.repository.GetUserByApiKey(id)
+
+	if err != nil {
+		return nil, errors.New("Access denied")
+	}
+
+	auth.repository.UpdateApiKeyActivity(id)
+
+	return u, nil
+}
+
+func (auth *GormAuthService) AuthenticateEmailVerifyCode(code string) (*types.User, error) {
+	u, err := auth.repository.GetUserByEmailVerifyCode(code)
+
+	if err != nil {
+		return nil, errors.New("Access denied")
+	}
+
+	return u, nil
+}
diff --git a/core/auth/auth_test.go b/core/auth/auth_test.go
index 3cb96df..2394547 100644
--- a/core/auth/auth_test.go
+++ b/core/auth/auth_test.go
@@ -2,12 +2,13 @@ package auth
 
 import (
 	"errors"
+	"testing"
+	"time"
+
 	"github.com/openaccounting/oa-server/core/model/db"
 	"github.com/openaccounting/oa-server/core/model/types"
 	"github.com/openaccounting/oa-server/core/util"
 	"github.com/stretchr/testify/assert"
-	"testing"
-	"time"
 )
 
 type TdUser struct {
@@ -28,18 +29,19 @@ func (td *TdUser) GetVerifiedUserByEmail(email string) (*types.User, error) {
 
 func (td *TdUser) GetVerifiedUserByEmail_1(email string) (*types.User, error) {
 	return &types.User{
-		"1",
-		time.Unix(0, 0),
-		time.Unix(0, 0),
-		"John",
-		"Doe",
-		"johndoe@email.com",
-		"password",
-		"$2a$10$KrtvADe7jwrmYIe3GXFbNupOQaPIvyOKeng5826g4VGOD47TpAisG",
-		true,
-		"",
-		false,
-		"",
+		Id:              "1",
+		Inserted:        time.Unix(0, 0),
+		Updated:         time.Unix(0, 0),
+		FirstName:       "John",
+		LastName:        "Doe",
+		Email:           "johndoe@email.com",
+		Password:        "password",
+		PasswordHash:    "$2a$10$KrtvADe7jwrmYIe3GXFbNupOQaPIvyOKeng5826g4VGOD47TpAisG",
+		AgreeToTerms:    true,
+		PasswordReset:   "",
+		EmailVerified:   false,
+		EmailVerifyCode: "",
+		SignupSource:    "",
 	}, nil
 }