SAML SSO Implementation in Golang: A Comprehensive Step-by-Step Guide
Tags: webdev, programming, tutorial, go
Published: 2023-05-06 09:31:48

## **Introduction**

The Security Assertion Markup Language (SAML) is a widely recognized standard protocol that enables secure authentication and authorization between two distinct systems. SAML provides a secure means for exchanging information between two parties, eliminating the need to store user credentials in multiple locations. SAML is extensively used in enterprise environments to facilitate a Single Sign-On (SSO) solution for various applications. This article aims to guide you through implementing SAML in Golang by providing a sample code to assist you in getting started. We will cover all the essential aspects of SAML implementation in Golang that you need to know to get started. Let’s get started

**Step 1: Install the necessary packages**

You need to install the following packages using the go get command for SAML implementation in GoLang:

```
go get -u github.com/crewjam/saml github.com/crewjam/saml/samlsp
```


**Step 2: Create a SAML Service Provider**

Create a SAML Service Provider (SP) to receive and process SAML responses from the Identity Provider (IdP) using the `samlsp.Middleware` struct:

```
sp, err := samlsp.New(samlsp.Options{
    IDPMetadataURL: "https://idp.example.com/metadata",
    SAMLNameIDFormat: "urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified",
    RelayState: "https://app.example.com/after-auth",
    PrivateKeyFile: "sp-key.pem",
    CertificateFile: "sp-cert.pem",
})

http.HandleFunc("/saml/acs", func(w http.ResponseWriter, r *http.Request) {
    err := sp.ServeHTTP(w, r)
    if err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }
    http.Redirect(w, r, sp.DefaultRedirectURI(), http.StatusFound)
})

log.Fatal(http.ListenAndServe(":8080", nil))
```


**Step 3: Create a SAML Identity Provider**

To create a SAML Identity Provider (IdP), use the `saml.IdentityProvider` struct:

```
keyPair, _ := tls.LoadX509KeyPair("idp-cert.pem", "idp-key.pem")
idp := &saml.IdentityProvider{
    Key:         keyPair.PrivateKey,
    Certificate: keyPair.Certificate,
    IDPMetadata: &saml.EntityDescriptor{
        ID:    "_12345",
        EntityID: "https://idp.example.com/metadata",
        RoleDescriptors: []saml.RoleDescriptor{
            &saml.IDPSSODescriptor{
                ProtocolSupportEnumeration: []string{
                    "urn:oasis:names:tc:SAML:2.0:protocol",
                },
                KeyDescriptors: []saml.KeyDescriptor{
                    &saml.KeyDescriptor{
                        Use: "signing",
                        KeyInfo: &ds.KeyInfo{
                            X509Datas: []ds.X509Data{
                                ds.X509Data{
                                    X509Certificates: []ds.X509Certificate{
                                        ds.X509Certificate{
                                            Data: certData,
                                        },
                                    },
                                },
                            },
                        },
                    },
                },
                SingleLogoutServices: []saml.Endpoint{
                    saml.Endpoint{
                        Binding:  saml.HTTPRedirectBinding,
                        Location: "https://idp.example.com/sls",
                    },
                },
                NameIDFormats: []string{
                    "urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified",
                },
                SingleSignOnServices: []saml.Endpoint{
                    saml.Endpoint{
                        Binding:  saml.HTTPRedirectBinding,
                        Location: "https://idp.example.com/sso",
                    },
                },
            },
        },
    },
}
```

**Step 4: Generate a SAML AuthnRequest**

To generate a SAML AuthnRequest, use the `samlsp.AuthRequest` function:

```
authnRequest, err := sp.MakeAuthRedirect(r.Context(), saml.IDPSSOBindingPOST)
if err != nil {
    http.Error(w, err.Error(), http.StatusInternalServerError)
    return
}

http.Redirect(w, r, authnRequest, http.StatusFound)
```


**Step 5: Process the SAML Response**

To process the SAML response, use the `sp.ServeHTTP` method:

```
err := sp.ServeHTTP(w, r)
if err != nil {
    http.Error(w, err.Error(), http.StatusInternalServerError)
    return
}

http.Redirect(w, r, sp.DefaultRedirectURI(), http.StatusFound)
```

And that’s it! You have successfully implemented SAML in Golang.

## **Conclusion**

To sum up, we have furnished a detailed guide on implementing SAML in Golang, along with a sample code to assist you in commencing the process. SAML implementation in Golang offers a secure means of authentication and authorization between two distinct systems.

SAML is a commonly utilized protocol in enterprise settings, providing a Single Sign-On (SSO) resolution for multiple applications. This guide can assist you in implementing SAML in Golang without difficulty, enhancing the security of your web applications.

If you have any queries or suggestions, please let us know at support@ssojet.com. We would be happy to help you!