Add method to create an ssh token.

ca/provisioner.go

@@ -22,6 +22,7 @@ type Provisioner struct {
 	name          string
 	kid           string
 	audience      string
+	sshAudience   string
 	fingerprint   string
 	jwk           *jose.JSONWebKey
 	tokenLifetime time.Duration
@@ -60,6 +61,7 @@ func NewProvisioner(name, kid, caURL string, password []byte, opts ...ClientOpti
 		name:          name,
 		kid:           jwk.KeyID,
 		audience:      client.endpoint.ResolveReference(&url.URL{Path: "/1.0/sign"}).String(),
+		sshAudience:   client.endpoint.ResolveReference(&url.URL{Path: "/1.0/ssh/sign"}).String(),
 		fingerprint:   fp,
 		jwk:           jwk,
 		tokenLifetime: tokenLifetime,
@@ -116,6 +118,39 @@ func (p *Provisioner) Token(subject string, sans ...string) (string, error) {
 	return tok.SignedString(p.jwk.Algorithm, p.jwk.Key)
 }
 
+func (p *Provisioner) SSHToken(certType, keyID string, principals []string) (string, error) {
+	jwtID, err := randutil.Hex(64)
+	if err != nil {
+		return "", err
+	}
+
+	notBefore := time.Now()
+	notAfter := notBefore.Add(tokenLifetime)
+	tokOptions := []token.Options{
+		token.WithJWTID(jwtID),
+		token.WithKid(p.kid),
+		token.WithIssuer(p.name),
+		token.WithAudience(p.sshAudience),
+		token.WithValidity(notBefore, notAfter),
+		token.WithSSH(provisioner.SSHOptions{
+			CertType:   certType,
+			Principals: principals,
+			KeyID:      keyID,
+		}),
+	}
+
+	if p.fingerprint != "" {
+		tokOptions = append(tokOptions, token.WithSHA(p.fingerprint))
+	}
+
+	tok, err := provision.New(keyID, tokOptions...)
+	if err != nil {
+		return "", err
+	}
+
+	return tok.SignedString(p.jwk.Algorithm, p.jwk.Key)
+}
+
 func decryptProvisionerJWK(encryptedKey string, password []byte) (*jose.JSONWebKey, error) {
 	enc, err := jose.ParseEncrypted(encryptedKey)
 	if err != nil {

ca/provisioner_test.go

@@ -198,3 +198,105 @@ func TestProvisioner_Token(t *testing.T) {
 		})
 	}
 }
+
+func TestProvisioner_SSHToken(t *testing.T) {
+	p := getTestProvisioner(t, "https://127.0.0.1:9000")
+	sha := "ef742f95dc0d8aa82d3cca4017af6dac3fce84290344159891952d18c53eefe7"
+
+	type fields struct {
+		name          string
+		kid           string
+		fingerprint   string
+		jwk           *jose.JSONWebKey
+		tokenLifetime time.Duration
+	}
+	type args struct {
+		certType   string
+		keyID      string
+		principals []string
+	}
+	tests := []struct {
+		name    string
+		fields  fields
+		args    args
+		wantErr bool
+	}{
+		{"ok", fields{p.name, p.kid, sha, p.jwk, p.tokenLifetime}, args{"user", "foo@smallstep.com", []string{"foo"}}, false},
+		{"ok host", fields{p.name, p.kid, sha, p.jwk, p.tokenLifetime}, args{"host", "foo.smallstep.com", []string{"foo.smallstep.com"}}, false},
+		{"ok multiple principals", fields{p.name, p.kid, sha, p.jwk, p.tokenLifetime}, args{"user", "foo@smallstep.com", []string{"foo", "bar"}}, false},
+		{"fail-no-subject", fields{p.name, p.kid, sha, p.jwk, p.tokenLifetime}, args{"user", "", []string{"foo"}}, true},
+		{"fail-no-key", fields{p.name, p.kid, sha, &jose.JSONWebKey{}, p.tokenLifetime}, args{"user", "foo@smallstep.com", []string{"foo"}}, true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			p := &Provisioner{
+				name:          tt.fields.name,
+				kid:           tt.fields.kid,
+				audience:      "https://127.0.0.1:9000/1.0/sign",
+				sshAudience:   "https://127.0.0.1:9000/1.0/ssh/sign",
+				fingerprint:   tt.fields.fingerprint,
+				jwk:           tt.fields.jwk,
+				tokenLifetime: tt.fields.tokenLifetime,
+			}
+			got, err := p.SSHToken(tt.args.certType, tt.args.keyID, tt.args.principals)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Provisioner.SSHToken() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+
+			if tt.wantErr == false {
+				jwt, err := jose.ParseSigned(got)
+				if err != nil {
+					t.Error(err)
+					return
+				}
+				var claims jose.Claims
+				if err := jwt.Claims(tt.fields.jwk.Public(), &claims); err != nil {
+					t.Error(err)
+					return
+				}
+				if err := claims.ValidateWithLeeway(jose.Expected{
+					Audience: []string{"https://127.0.0.1:9000/1.0/ssh/sign"},
+					Issuer:   tt.fields.name,
+					Subject:  tt.args.keyID,
+					Time:     time.Now().UTC(),
+				}, time.Minute); err != nil {
+					t.Error(err)
+					return
+				}
+				lifetime := claims.Expiry.Time().Sub(claims.NotBefore.Time())
+				if lifetime != tt.fields.tokenLifetime {
+					t.Errorf("Claims token life time = %s, want %s", lifetime, tt.fields.tokenLifetime)
+				}
+				allClaims := make(map[string]interface{})
+				if err := jwt.Claims(tt.fields.jwk.Public(), &allClaims); err != nil {
+					t.Error(err)
+					return
+				}
+				if v, ok := allClaims["sha"].(string); !ok || v != sha {
+					t.Errorf("Claim sha = %s, want %s", v, sha)
+				}
+
+				principals := make([]interface{}, len(tt.args.principals))
+				for i, p := range tt.args.principals {
+					principals[i] = p
+				}
+				want := map[string]interface{}{
+					"ssh": map[string]interface{}{
+						"certType":    tt.args.certType,
+						"keyID":       tt.args.keyID,
+						"principals":  principals,
+						"validAfter":  "",
+						"validBefore": "",
+					},
+				}
+				if !reflect.DeepEqual(allClaims["step"], want) {
+					t.Errorf("Claim step = %s, want %s", allClaims["step"], want)
+				}
+				if v, ok := allClaims["jti"].(string); !ok || v == "" {
+					t.Errorf("Claim jti = %s, want not blank", v)
+				}
+			}
+		})
+	}
+}