Add certificate extract command for conversion between P12, PEM, and DER

command/certificate/format.go

@@ -6,30 +6,43 @@ import (
 	"encoding/pem"
 	"os"
 
+	"go.step.sm/crypto/pemutil"
+
 	"github.com/pkg/errors"
 	"github.com/smallstep/cli/flags"
 	"github.com/smallstep/cli/ui"
 	"github.com/smallstep/cli/utils"
 	"github.com/urfave/cli"
 	"go.step.sm/cli-utils/command"
 	"go.step.sm/cli-utils/errs"
+
+	"software.sslmate.com/src/go-pkcs12"
 )
 
 func formatCommand() cli.Command {
 	return cli.Command{
-		Name:      "format",
-		Action:    command.ActionFunc(formatAction),
-		Usage:     `reformat certificate`,
-		UsageText: `**step certificate format** <crt-file> [**--out**=<file>]`,
+		Name:   "format",
+		Action: command.ActionFunc(formatAction),
+		Usage:  `reformat certificate`,
+		UsageText: `**step certificate format** <crt-file> [**--crt**=<file>] [**--key**=<file>]
+[**--ca**=<file>] [**--out**=<file>] [**--format**=<format>]`,
 		Description: `**step certificate format** prints the certificate or CSR in a different format.
 
-Only 2 formats are currently supported; PEM and ASN.1 DER. This tool will convert
-a certificate or CSR in one format to the other.
+If either PEM or ASN.1 DER is provided as a positional argument, this command
+will convert a certificate or CSR in one format to the other.
+
+If PFX / PKCS12 file is provided as a positional argument, and the format is
+specified as "pem"/"der", this command extracts a certificate and private key
+from the input.
+
+If either PEM or ASN.1 DER is provided in "--crt" | "--key" | "--ca", and the
+format is specified as "p12", this command creates a PFX / PKCS12 file from the input .
 
 ## POSITIONAL ARGUMENTS
 
 <crt-file>
-:  Path to a certificate or CSR file.
+:  Path to a certificate, CSR, or .p12 file.
+<crt-file>
 
 ## EXIT CODES
 
@@ -51,12 +64,72 @@ Convert PEM format to DER and write to disk:
 '''
 $ step certificate format foo.pem --out foo.der
 '''
+
+Convert a .p12 file to a certificate and private key:
+
+'''
+$ step certificate format foo.p12 --crt foo.crt --key foo.key --format pem
+'''
+
+Convert a .p12 file to a certificate, private key and intermediate certificates:
+
+'''
+$ step certificate format foo.p12 --crt foo.crt --key foo.key --ca intermediate.crt --format pem
+'''
+
+Convert a certificate and private key to a .p12 file:
+
+'''
+$ step certificate format foo.crt --crt foo.p12 --key foo.key --format p12
+'''
+
+Convert a certificate, a private key, and intermediate certificates(s) to a .p12 file:
+
+'''
+$ step certificate format foo.crt --crt foo.p12 --key foo.key \
+  --ca intermediate-1.crt --ca intermediate-2 --format p12
+'''
 `,
 		Flags: []cli.Flag{
 			cli.StringFlag{
-				Name:  "out",
-				Usage: `Path to write the reformatted result.`,
+				Name: "format",
+				Usage: `The desired output <format> for the input. The default behavior is to
+convert between DER and PEM format. Acceptable formats are 'pem', 'der', and 'p12'.`,
+			},
+			cli.StringFlag{
+				Name: "crt",
+				Usage: `The path to a certificate <file>. If --format is 'p12' then this flag
+must be a PEM or DER encoded certificate. If the positional argument is a P12
+encoded file then this flag contains the name for the PEM or DER encoded leaf
+certificate extracted from the p12 file.`,
+			},
+			cli.StringFlag{
+				Name: "key",
+				Usage: `The path to a key <file>. If --format is 'p12' then this flag
+must be a PEM or DER encoded private key. If the positional argument is a P12
+encoded file then this flag contains the name for the PEM or DER encoded private
+key extracted from the p12 file.`,
 			},
+			cli.StringSliceFlag{
+				Name: "ca",
+				Usage: `The path to a root or intermediate certificate <file>. If --format is 'p12'
+then this flag can be used to submit one or more CA files encoded as PEM or DER.
+Additional CA certificates can be added by using the --ca flag multiple times.
+If the positional argument is a p12 encoded file then this flag contains the
+name for the PEM or DER encoded certificate chain extracted from the p12 file.`,
+			},
+			cli.StringFlag{
+				Name: "out",
+				Usage: `The <file> to write the reformatted result. Only use this flag
+for conversions between PEM and DER. Conversions to P12 should use --crt, --key,
+and --ca.`,
+			},
+			cli.StringFlag{
+				Name:  "password-file",
+				Usage: `The path to the <file> containing the password to encrypt/decrypt the .p12 file.`,
+			},
+			flags.NoPassword,
+			flags.Insecure,
 			flags.Force,
 		},
 	}
@@ -67,15 +140,97 @@ func formatAction(ctx *cli.Context) error {
 		return err
 	}
 
+	sourceFile := ctx.Args().First()
+	format := ctx.String("format")
+	crtFile := ctx.String("crt")
+	keyFile := ctx.String("key")
+	caFiles := ctx.StringSlice("ca")
+	out := ctx.String("out")
+	passwordFile := ctx.String("password-file")
+	noPassword := ctx.Bool("no-password")
+	insecure := ctx.Bool("insecure")
+
+	if out != "" {
+		if crtFile != "" {
+			return errs.IncompatibleFlagWithFlag(ctx, "out", "crt")
+		}
+		if keyFile != "" {
+			return errs.IncompatibleFlagWithFlag(ctx, "out", "key")
+		}
+		if format != "" {
+			return errs.IncompatibleFlagWithFlag(ctx, "out", "format")
+		}
+	}
+
+	if passwordFile != "" && noPassword {
+		return errs.IncompatibleFlagWithFlag(ctx, "no-password", "password-file")
+	}
+
 	var (
-		out = ctx.String("out")
-		ob  []byte
+		err  error
+		pass = ""
 	)
+	if passwordFile != "" {
+		pass, err = utils.ReadStringPasswordFromFile(passwordFile)
+		if err != nil {
+			return errs.FileError(err, passwordFile)
+		}
+	}
 
-	var crtFile string
-	if ctx.NArg() == 1 {
-		crtFile = ctx.Args().First()
-	} else {
+	if sourceFile != "" {
+		srcBytes, err := os.ReadFile(sourceFile)
+		if err != nil {
+			return errs.FileError(err, sourceFile)
+		}
+
+		// First check if P12 input.
+		if keyFrom, crtFrom, caFrom, err := pkcs12.DecodeChain(srcBytes, pass); err == nil {
+			if format == "p12" {
+				return errors.Errorf("invalid flag --format with value 'p12'; cannot from P12 format to P12 format")
+			}
+			if len(caFrom) > 1 {
+				return errors.Errorf("flag --ca cannot be used multiple times when converting from P12 format")
+			}
+			caFile := ""
+			if len(caFiles) == 1 {
+				caFile = caFiles[0]
+			}
+			if err := write(crtFile, format, crtFrom); err != nil {
+				return err
+			}
+
+			if err := writeCerts(caFile, format, caFrom); err != nil {
+				return err
+			}
+
+			if err := write(keyFile, format, keyFrom); err != nil {
+				return err
+			}
+		}
+
+		// Now we know input is not P12 format. Check if we're converting to P12.
+		if format == "p12" {
+			if noPassword && !insecure {
+				return errs.RequiredInsecureFlag(ctx, "no-password")
+			}
+			return ToP12(out, crtFile, keyFile, caFiles, passwordFile, noPassword, insecure)
+		}
+
+		// Otherwise interconvert between PEM and DER.
+		return interconvertPemAndDer(sourceFile, out)
+	}
+
+	// If format is PEM or DER (not P12) then an input certificate file is required.
+	if format != "p12" {
+		return errors.Errorf("flag --format with value '%s' requires a certificate file as positional argument", format)
+	}
+	return ToP12(out, crtFile, keyFile, caFiles, passwordFile, noPassword, insecure)
+}
+
+func interconvertPemAndDer(crtFile, out string) error {
+	var ob []byte
+
+	if crtFile == "" {
 		crtFile = "-"
 	}
 
@@ -116,7 +271,7 @@ func formatAction(ctx *cli.Context) error {
 			}
 		}
 		if err := utils.WriteFile(out, ob, mode); err != nil {
-			return err
+			return errs.FileError(err, out)
 		}
 		ui.Printf("Your certificate has been saved in %s\n", out)
 	}
@@ -133,21 +288,95 @@ func decodeCertificatePem(b []byte) ([]byte, error) {
 		}
 		switch block.Type {
 		case "CERTIFICATE":
-			crt, err := x509.ParseCertificate(block.Bytes)
-			if err != nil {
+			if _, err := x509.ParseCertificate(block.Bytes); err != nil {
 				return nil, errors.Wrap(err, "error parsing certificate")
 			}
-			return crt.Raw, nil
+			return block.Bytes, nil
 		case "CERTIFICATE REQUEST":
-			csr, err := x509.ParseCertificateRequest(block.Bytes)
-			if err != nil {
+			if _, err := x509.ParseCertificateRequest(block.Bytes); err != nil {
 				return nil, errors.Wrap(err, "error parsing certificate request")
 			}
-			return csr.Raw, nil
+			return block.Bytes, nil
+		case "RSA PRIVATE KEY":
+			if _, err := x509.ParsePKCS1PrivateKey(block.Bytes); err != nil {
+				return nil, errors.Wrap(err, "error parsing RSA private key")
+			}
+			return block.Bytes, nil
+		case "EC PRIVATE KEY":
+			if _, err := x509.ParseECPrivateKey(block.Bytes); err != nil {
+				return nil, errors.Wrap(err, "error parsing EC private key")
+			}
+			return block.Bytes, nil
+		case "PRIVATE KEY":
+			if _, err := x509.ParsePKCS8PrivateKey(block.Bytes); err != nil {
+				return nil, errors.Wrap(err, "error parsing private key")
+			}
+
+			return block.Bytes, nil
 		default:
 			continue
 		}
 	}
 
 	return nil, errors.Errorf("error decoding certificate: invalid PEM block")
 }
+
+func writeCerts(filename, format string, certs []*x509.Certificate) error {
+	if len(certs) > 1 && format == "der" {
+		return errors.Errorf("der format does not support a certificate bundle")
+	}
+	var data []byte
+	for _, cert := range certs {
+		b, err := toByte(cert, format)
+		if err != nil {
+			return err
+		}
+		data = append(data, b...)
+	}
+	if err := maybeWrite(filename, data); err != nil {
+		return err
+	}
+	return nil
+}
+
+func write(filename, format string, in interface{}) error {
+	b, err := toByte(in, format)
+	if err != nil {
+		return err
+	}
+	if err := maybeWrite(filename, b); err != nil {
+		return err
+	}
+	return nil
+}
+
+func maybeWrite(filename string, out []byte) error {
+	if filename == "" {
+		os.Stdout.Write(out)
+	} else {
+		if err := utils.WriteFile(filename, out, 0600); err != nil {
+			return errs.FileError(err, filename)
+		}
+	}
+	return nil
+}
+
+func toByte(in interface{}, format string) ([]byte, error) {
+	pemblk, err := pemutil.Serialize(in)
+	if err != nil {
+		return nil, err
+	}
+	pemByte := pem.EncodeToMemory(pemblk)
+	switch format {
+	case "der":
+		derByte, err := decodeCertificatePem(pemByte)
+		if err != nil {
+			return nil, err
+		}
+		return derByte, nil
+	case "pem", "":
+		return pemByte, nil
+	default:
+		return nil, errors.Errorf("unsupported format: %s", format)
+	}
+}

command/certificate/p12.go

@@ -3,6 +3,7 @@ package certificate
 import (
 	"crypto/rand"
 	"crypto/x509"
+	"os"
 
 	"github.com/pkg/errors"
 	"github.com/smallstep/cli/crypto/pemutil"
@@ -85,6 +86,10 @@ func p12Action(ctx *cli.Context) error {
 	caFiles := ctx.StringSlice("ca")
 	hasKeyAndCert := crtFile != "" && keyFile != ""
 
+	passwordFile := ctx.String("password-file")
+	noPassword := ctx.Bool("no-password")
+	insecure := ctx.Bool("insecure")
+
 	// If either key or cert are provided, both must be provided
 	if !hasKeyAndCert && (crtFile != "" || keyFile != "") {
 		return errs.MissingArguments(ctx, "key_file")
@@ -97,13 +102,20 @@ func p12Action(ctx *cli.Context) error {
 
 	// Validate flags
 	switch {
-	case ctx.String("password-file") != "" && ctx.Bool("no-password"):
+	case passwordFile != "" && noPassword:
 		return errs.IncompatibleFlagWithFlag(ctx, "no-password", "password-file")
-	case ctx.Bool("no-password") && !ctx.Bool("insecure"):
+	case noPassword && !insecure:
 		return errs.RequiredInsecureFlag(ctx, "no-password")
 	}
 
-	x509CAs := []*x509.Certificate{}
+	if err := ToP12(p12File, crtFile, keyFile, caFiles, passwordFile, noPassword, insecure); err != nil {
+		return err
+	}
+	return nil
+}
+
+func ToP12(p12File, crtFile, keyFile string, caFiles []string, passwordFile string, noPassword, insecure bool) error {
+	var x509CAs []*x509.Certificate
 	for _, caFile := range caFiles {
 		x509Bundle, err := pemutil.ReadCertificateBundle(caFile)
 		if err != nil {
@@ -114,8 +126,8 @@ func p12Action(ctx *cli.Context) error {
 
 	var err error
 	var password string
-	if !ctx.Bool("no-password") {
-		if passwordFile := ctx.String("password-file"); passwordFile != "" {
+	if !noPassword {
+		if passwordFile != "" {
 			password, err = utils.ReadStringPasswordFromFile(passwordFile)
 			if err != nil {
 				return err
@@ -132,7 +144,7 @@ func p12Action(ctx *cli.Context) error {
 	}
 
 	var pkcs12Data []byte
-	if hasKeyAndCert {
+	if crtFile != "" && keyFile != "" {
 		// If we have a key and certificate, we're making an identity store
 		x509CertBundle, err := pemutil.ReadCertificateBundle(crtFile)
 		if err != nil {
@@ -146,7 +158,7 @@ func p12Action(ctx *cli.Context) error {
 
 		// The first certificate in the bundle will be our server cert
 		x509Cert := x509CertBundle[0]
-		// Any remaning certs will be intermediates for the server
+		// Any remaining certs will be intermediates for the server
 		x509CAs = append(x509CAs, x509CertBundle[1:]...)
 
 		pkcs12Data, err = pkcs12.Encode(rand.Reader, key, x509Cert, x509CAs, password)
@@ -161,10 +173,16 @@ func p12Action(ctx *cli.Context) error {
 		}
 	}
 
-	if err := utils.WriteFile(p12File, pkcs12Data, 0600); err != nil {
-		return err
+	if p12File != "" {
+		if err := utils.WriteFile(p12File, pkcs12Data, 0600); err != nil {
+			return err
+		}
+		ui.Printf("Your .p12 bundle has been saved as %s.\n", p12File)
+	} else {
+		if _, err := os.Stdout.Write(pkcs12Data); err != nil {
+			return err
+		}
 	}
 
-	ui.Printf("Your .p12 bundle has been saved as %s.\n", p12File)
 	return nil
 }

integration/certificate_format_test.go

@@ -0,0 +1,183 @@
+//go:build integration
+
+package integration
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/smallstep/assert"
+	"github.com/smallstep/cli/crypto/pemutil"
+	"github.com/smallstep/cli/utils"
+)
+
+func TestCertificateFormat(t *testing.T) {
+	setup()
+	t.Run("validate cert and key extraction from p12", func(t *testing.T) {
+        _, err := NewCLICommand().
+			setCommand(fmt.Sprintf("../bin/step certificate format %s", temp("foo.p12"))).
+			setFlag("crt", temp("foo_out0.crt")).
+			setFlag("key", temp("foo_out0.key")).
+			setFlag("ca", temp("intermediate-ca_out0.crt")).
+			setFlag("format", "pem").
+			setFlag("no-password", "").
+			run()
+		assert.Nil(t, err)
+
+		foo_crt, _ := pemutil.ReadCertificate(temp("foo.crt"))
+		foo_crt_out, _ := pemutil.ReadCertificate(temp("foo_out0.crt"))
+		assert.Equals(t, foo_crt, foo_crt_out)
+
+		foo_key, _ := utils.ReadFile(temp("foo.key"))
+		foo_out_key, _ := utils.ReadFile(temp("foo_out0.key"))
+		assert.Equals(t, foo_key, foo_out_key)
+
+		foo_ca, _ := pemutil.ReadCertificate(temp("intermediate-ca_out0.crt"))
+		foo_ca_out, _ := pemutil.ReadCertificate(temp("intermediate-ca_out0.crt"))
+		assert.Equals(t, foo_ca, foo_ca_out)
+	})
+
+	t.Run("validate cert and key packaging to p12", func(t *testing.T) {
+		_, err := NewCLICommand().
+			setCommand(fmt.Sprintf("../bin/step certificate format %s", temp("foo.crt"))).
+			setFlag("crt", temp("foo_format.p12")).
+			setFlag("key", temp("foo.key")).
+			setFlag("ca", temp("intermediate-ca.crt")).
+			setFlag("format", "p12").
+			setFlag("no-password", "").
+			setFlag("insecure", "").
+			run()
+		assert.Nil(t, err)
+
+		_, err = NewCLICommand().
+			setCommand(fmt.Sprintf("../bin/step certificate format %s", temp("foo_format.p12"))).
+			setFlag("crt", temp("foo_out1.crt")).
+			setFlag("key", temp("foo_out1.key")).
+			setFlag("ca", temp("intermediate-ca_out1.crt")).
+			setFlag("format", "pem").
+			setFlag("no-password", "").
+			run()
+
+		assert.Nil(t, err)
+
+		foo_crt, _ := pemutil.ReadCertificate(temp("foo.crt"))
+		foo_crt_out, _ := pemutil.ReadCertificate(temp("foo_out1.crt"))
+		assert.Equals(t, foo_crt, foo_crt_out)
+
+		foo_key, _ := utils.ReadFile(temp("foo.key"))
+		foo_out_key, _ := utils.ReadFile(temp("foo_out1.key"))
+		assert.Equals(t, foo_key, foo_out_key)
+
+		foo_ca, _ := pemutil.ReadCertificate(temp("intermediate-ca.crt"))
+		foo_ca_out, _ := pemutil.ReadCertificate(temp("intermediate-ca_out1.crt"))
+		assert.Equals(t, foo_ca, foo_ca_out)
+	})
+
+	t.Run("validate stdout output", func(t *testing.T) {
+        output, err := NewCLICommand().
+			setCommand(fmt.Sprintf("../bin/step certificate format %s", temp("foo.p12"))).
+			setFlag("no-password", "").
+			setFlag("key", temp("temp.key")).
+			setFlag("ca", temp("temp.crt")).
+			setFlag("format", "pem").
+			run()
+		assert.Nil(t, err)
+
+		foo_crt, _ := pemutil.ReadCertificate(temp("foo.crt"))
+		foo_crt_out, _ := pemutil.Parse([]byte(output.stdout))
+		assert.Equals(t, foo_crt, foo_crt_out)
+	})
+
+	t.Run("compare der format", func(t *testing.T) {
+		_, err := NewCLICommand().
+			setCommand(fmt.Sprintf("../bin/step certificate format")).
+			setArguments(temp("foo.crt")).
+			setFlag("out", temp("foo.der")).
+			run()
+		assert.Nil(t, err)
+
+
+		_, err = NewCLICommand().
+			setCommand(fmt.Sprintf("../bin/step certificate format %s", temp("foo.p12"))).
+			setFlag("no-password", "").
+			setFlag("format", "der").
+			setFlag("crt", temp("foo_cmp.der")).
+			run()
+
+		assert.Nil(t, err)
+
+		foo_crt, _ := pemutil.ReadCertificate(temp("foo.der"))
+		foo_crt_out, _ := pemutil.ReadCertificate(temp("foo_cmp.der"))
+		assert.Equals(t, foo_crt, foo_crt_out)
+	})
+
+	t.Run("validate interconversion between PEM and DER", func(t *testing.T) {
+		_, err := NewCLICommand().
+			setCommand(fmt.Sprintf("../bin/step certificate format")).
+			setArguments(temp("foo.crt")).
+			setFlag("out", temp("foo_inter.der")).
+			run()
+		assert.Nil(t, err)
+
+		_, err = NewCLICommand().
+			setCommand(fmt.Sprintf("../bin/step certificate format")).
+			setArguments(temp("foo_inter.der")).
+			setFlag("out", temp("foo_inter.crt")).
+			run()
+		assert.Nil(t, err)
+
+		assert.Nil(t, err)
+
+		foo_crt, _ := pemutil.ReadCertificate(temp("foo.crt"))
+		foo_crt_out, _ := pemutil.ReadCertificate(temp("foo_inter.crt"))
+		assert.Equals(t, foo_crt, foo_crt_out)
+	})
+
+	t.Run("assert incompatible flag", func(t *testing.T) {
+		output, _ := NewCLICommand().
+			setCommand(fmt.Sprintf("../bin/step certificate format %s", temp("foo.p12"))).
+			setFlag("out", temp("some")).
+			setFlag("key", temp("some")).
+			run()
+		assert.Equals(t, "flag '--out' is incompatible with '--key'\n", output.stderr)
+	})
+
+}
+
+func setup() {
+	NewCLICommand().
+		setCommand(fmt.Sprintf("../bin/step certificate create root-ca %s %s", temp("root-ca.crt"), temp("root-ca.key"))).
+		setFlag("profile", "root-ca").
+		setFlag("no-password", "").
+		setFlag("insecure", "").
+		run()
+
+	NewCLICommand().
+		setCommand(fmt.Sprintf("../bin/step certificate create intermediate-ca %s %s", temp("intermediate-ca.crt"), temp("intermediate-ca.key"))).
+		setFlag("profile", "intermediate-ca").
+		setFlag("ca", temp("root-ca.crt")).
+		setFlag("ca-key", temp("root-ca.key")).
+		setFlag("no-password", "").
+		setFlag("insecure", "").
+		run()
+
+	NewCLICommand().
+		setCommand(fmt.Sprintf("../bin/step certificate create foo %s %s", temp("foo.crt"), temp("foo.key"))).
+		setFlag("profile", "leaf").
+		setFlag("ca", temp("intermediate-ca.crt")).
+		setFlag("ca-key", temp("intermediate-ca.key")).
+		setFlag("no-password", "").
+		setFlag("insecure", "").
+		run()
+
+	NewCLICommand().
+		setCommand(fmt.Sprintf("../bin/step certificate p12 %s %s %s", temp("foo.p12"), temp("foo.crt"), temp("foo.key"))).
+		setFlag("ca", temp("intermediate-ca.crt")).
+		setFlag("no-password", "").
+		setFlag("insecure", "").
+		run()
+}
+
+func temp(filename string) string {
+	return fmt.Sprintf("%s/%s", TempDirectory, filename)
+}