Add RSS PSS SignerVerifier

Signed-off-by: Aditya Sirish <[email protected]>

Author: adityasaky

go.mod

@@ -1,6 +1,6 @@
 module github.com/secure-systems-lab/go-securesystemslib
 
-go 1.17
+go 1.20
 
 require (
 	github.com/codahale/rfc6979 v0.0.0-20141003034818-6a90f24967eb

signerverifier/ed25519.go

@@ -5,6 +5,7 @@ import (
 	"crypto"
 	"crypto/ed25519"
 	"encoding/hex"
+	"os"
 )
 
 const Ed25519KeyType = "ed25519"
@@ -77,3 +78,12 @@ func (sv Ed25519SignerVerifier) KeyID() (string, error) {
 func (sv Ed25519SignerVerifier) Public() crypto.PublicKey {
 	return sv.public
 }
+
+func LoadEd25519KeyFromFile(path string) (*SSLibKey, error) {
+	contents, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+
+	return loadKeyFromSSLibBytes(contents)
+}

signerverifier/ed25519_test.go

@@ -11,7 +11,7 @@ import (
 )
 
 func TestNewEd25519SignerVerifierFromSSLibKey(t *testing.T) {
-	key, err := LoadKeyFromFile(filepath.Join("test-data", "ed25519-test-key.pub"))
+	key, err := LoadEd25519KeyFromFile(filepath.Join("test-data", "ed25519-test-key.pub"))
 	if err != nil {
 		t.Error(err)
 	}
@@ -30,7 +30,7 @@ func TestNewEd25519SignerVerifierFromSSLibKey(t *testing.T) {
 }
 
 func TestEd25519SignerVerifierSign(t *testing.T) {
-	key, err := LoadKeyFromFile(filepath.Join("test-data", "ed25519-test-key"))
+	key, err := LoadEd25519KeyFromFile(filepath.Join("test-data", "ed25519-test-key"))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -50,7 +50,7 @@ func TestEd25519SignerVerifierSign(t *testing.T) {
 	expectedSignature := []byte{0x80, 0x72, 0xb4, 0x31, 0xc5, 0xa3, 0x7e, 0xc, 0xf3, 0x91, 0x22, 0x3, 0x60, 0xbf, 0x92, 0xa4, 0x46, 0x31, 0x84, 0x83, 0xf1, 0x31, 0x3, 0xdc, 0xbc, 0x5, 0x6f, 0xab, 0x84, 0xe4, 0xdc, 0xe9, 0xf5, 0x1c, 0xa9, 0xb3, 0x95, 0xa5, 0xa0, 0x16, 0xd3, 0xaa, 0x4d, 0xe7, 0xde, 0xaf, 0xc2, 0x5e, 0x1e, 0x9a, 0x9d, 0xc8, 0xb2, 0x5c, 0x1c, 0x68, 0xf7, 0x28, 0xb4, 0x1, 0x4d, 0x9f, 0xc8, 0x4}
 	assert.Equal(t, expectedSignature, signature)
 
-	key, err = LoadKeyFromFile(filepath.Join("test-data", "ed25519-test-key.pub"))
+	key, err = LoadEd25519KeyFromFile(filepath.Join("test-data", "ed25519-test-key.pub"))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -65,7 +65,7 @@ func TestEd25519SignerVerifierSign(t *testing.T) {
 }
 
 func TestEd25519SignerVerifierVerify(t *testing.T) {
-	key, err := LoadKeyFromFile(filepath.Join("test-data", "ed25519-test-key.pub"))
+	key, err := LoadEd25519KeyFromFile(filepath.Join("test-data", "ed25519-test-key.pub"))
 	if err != nil {
 		t.Fatal(err)
 	}

signerverifier/rsa.go

@@ -0,0 +1,129 @@
+package signerverifier
+
+import (
+	"context"
+	"crypto"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/sha256"
+	"crypto/x509"
+	"errors"
+	"os"
+)
+
+// ErrNoPEMBlock gets triggered when there is no PEM block in the provided file
+var ErrNoPEMBlock = errors.New("failed to decode the data as PEM block (are you sure this is a pem file?)")
+
+// ErrFailedPEMParsing gets returned when PKCS1, PKCS8 or PKIX key parsing fails
+var ErrFailedPEMParsing = errors.New("failed parsing the PEM block: unsupported PEM type")
+
+const (
+	RSAKeyType       = "rsa"
+	RSAKeyScheme     = "rsassa-pss-sha256"
+	RSAPublicKeyPEM  = "PUBLIC KEY"
+	RSAPrivateKeyPEM = "RSA PRIVATE KEY"
+)
+
+type RSAPSSSignerVerifier struct {
+	keyID   string
+	private *rsa.PrivateKey
+	public  *rsa.PublicKey
+}
+
+func NewRSAPSSSignerVerifierFromSSLibKey(key *SSLibKey) (*RSAPSSSignerVerifier, error) {
+	_, publicParsedKey, err := decodeAndParsePEM([]byte(key.KeyVal.Public))
+	if err != nil {
+		return nil, err
+	}
+
+	if len(key.KeyVal.Private) > 0 {
+		_, privateParsedKey, err := decodeAndParsePEM([]byte(key.KeyVal.Private))
+		if err != nil {
+			return nil, err
+		}
+
+		return &RSAPSSSignerVerifier{
+			keyID:   key.KeyID(),
+			public:  publicParsedKey.(*rsa.PublicKey),
+			private: privateParsedKey.(*rsa.PrivateKey),
+		}, nil
+	}
+
+	return &RSAPSSSignerVerifier{
+		keyID:   key.KeyID(),
+		public:  publicParsedKey.(*rsa.PublicKey),
+		private: nil,
+	}, nil
+}
+
+func (sv *RSAPSSSignerVerifier) Sign(ctx context.Context, data []byte) ([]byte, error) {
+	if sv.private == nil {
+		return nil, ErrNotPrivateKey
+	}
+
+	hashedData := hashBeforeSigning(data)
+
+	return rsa.SignPSS(rand.Reader, sv.private, crypto.SHA256, hashedData, &rsa.PSSOptions{SaltLength: sha256.Size, Hash: crypto.SHA256})
+}
+
+func (sv RSAPSSSignerVerifier) Verify(ctx context.Context, data []byte, sig []byte) error {
+	hashedData := hashBeforeSigning(data)
+
+	if err := rsa.VerifyPSS(sv.public, crypto.SHA256, hashedData, sig, &rsa.PSSOptions{SaltLength: sha256.Size, Hash: crypto.SHA256}); err != nil {
+		return ErrSignatureVerificationFailed
+	}
+
+	return nil
+}
+
+func (sv RSAPSSSignerVerifier) KeyID() (string, error) {
+	return sv.keyID, nil
+}
+
+func (sv RSAPSSSignerVerifier) Public() crypto.PublicKey {
+	return sv.public
+}
+
+func LoadRSAPSSKeyFromFile(path string) (*SSLibKey, error) {
+	contents, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+
+	pemData, keyObj, err := decodeAndParsePEM(contents)
+	if err != nil {
+		return nil, err
+	}
+
+	key := &SSLibKey{
+		KeyType:             RSAKeyType,
+		Scheme:              RSAKeyScheme,
+		KeyIDHashAlgorithms: KeyIDHashAlgorithms,
+		KeyVal:              KeyVal{},
+	}
+
+	switch k := keyObj.(type) {
+	case *rsa.PublicKey:
+		pubKeyBytes, err := x509.MarshalPKIXPublicKey(k)
+		if err != nil {
+			return nil, err
+		}
+		key.KeyVal.Public = string(generatePEMBlock(pubKeyBytes, RSAPublicKeyPEM))
+
+	case *rsa.PrivateKey:
+		pubKeyBytes, err := x509.MarshalPKIXPublicKey(k.Public())
+		if err != nil {
+			return nil, err
+		}
+		key.KeyVal.Public = string(generatePEMBlock(pubKeyBytes, RSAPublicKeyPEM))
+		key.KeyVal.Private = string(generatePEMBlock(pemData.Bytes, RSAPrivateKeyPEM))
+	}
+
+	keyID, err := calculateKeyID(key)
+	if err != nil {
+		return nil, err
+	}
+	key.keyID = keyID
+
+	return key, nil
+}

signerverifier/rsa_test.go

@@ -0,0 +1,69 @@
+package signerverifier
+
+import (
+	"context"
+	"crypto/rsa"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewRSAPSSSignerVerifierFromSSLibKey(t *testing.T) {
+	key, err := LoadRSAPSSKeyFromFile(filepath.Join("test-data", "rsa-test-key.pub"))
+	if err != nil {
+		t.Error(err)
+	}
+
+	sv, err := NewRSAPSSSignerVerifierFromSSLibKey(key)
+	if err != nil {
+		t.Error(err)
+	}
+
+	expectedPublicString := "-----BEGIN PUBLIC KEY-----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\nEm53T13mZzYUvbLJ0q3aljZVLIC3IZn3ZwA2yCWchBkVAgMBAAE=\n-----END PUBLIC KEY-----"
+	_, expectedPublicKey, err := decodeAndParsePEM([]byte(expectedPublicString))
+	assert.Nil(t, err)
+
+	assert.Equal(t, "966c5d84ba73ccded42eb473c939d77336e4def253ffaf6739f8e983ef73dad8", sv.keyID) // FIXME: mismatch?
+	assert.Equal(t, expectedPublicKey.(*rsa.PublicKey), sv.public)
+	assert.Nil(t, sv.private)
+}
+
+func TestRSAPSSSignerVerifierSignAndVerify(t *testing.T) {
+	t.Run("using valid key", func(t *testing.T) {
+		key, err := LoadRSAPSSKeyFromFile(filepath.Join("test-data", "rsa-test-key"))
+		if err != nil {
+			t.Error(err)
+		}
+
+		sv, err := NewRSAPSSSignerVerifierFromSSLibKey(key)
+		if err != nil {
+			t.Error(err)
+		}
+
+		message := []byte("test message")
+
+		signature, err := sv.Sign(context.Background(), message)
+		assert.Nil(t, err)
+
+		err = sv.Verify(context.Background(), message, signature)
+		assert.Nil(t, err)
+	})
+
+	t.Run("using invalid key", func(t *testing.T) {
+		key, err := LoadRSAPSSKeyFromFile(filepath.Join("test-data", "rsa-test-key.pub"))
+		if err != nil {
+			t.Error(err)
+		}
+
+		sv, err := NewRSAPSSSignerVerifierFromSSLibKey(key)
+		if err != nil {
+			t.Error(err)
+		}
+
+		message := []byte("test message")
+
+		_, err = sv.Sign(context.Background(), message)
+		assert.ErrorIs(t, err, ErrNotPrivateKey)
+	})
+}

signerverifier/signerverifier.go

@@ -1,15 +1,11 @@
 package signerverifier
 
 import (
-	"crypto/sha256"
-	"encoding/hex"
-	"encoding/json"
 	"errors"
-	"os"
-
-	"github.com/secure-systems-lab/go-securesystemslib/cjson"
 )
 
+var KeyIDHashAlgorithms = []string{"sha256", "sha512"}
+
 var (
 	ErrNotPrivateKey               = errors.New("loaded key is not a private key")
 	ErrSignatureVerificationFailed = errors.New("failed to verify signature")
@@ -34,39 +30,3 @@ type KeyVal struct {
 	Public      string `json:"public"`
 	Certificate string `json:"certificate,omitempty"`
 }
-
-// LoadKeyFromBytes returns a pointer to a Key instance created from the
-// contents of the bytes. The key contents are expected to be in the custom
-// securesystemslib format.
-func LoadKeyFromBytes(contents []byte) (*SSLibKey, error) {
-	var key *SSLibKey
-	if err := json.Unmarshal(contents, &key); err != nil {
-		return nil, err
-	}
-
-	keyID, err := calculateKeyID(key)
-	if err != nil {
-		return nil, err
-	}
-	key.keyID = keyID
-
-	return key, nil
-}
-
-func LoadKeyFromFile(path string) (*SSLibKey, error) {
-	contents, err := os.ReadFile(path)
-	if err != nil {
-		return nil, err
-	}
-
-	return LoadKeyFromBytes(contents)
-}
-
-func calculateKeyID(k *SSLibKey) (string, error) {
-	canonical, err := cjson.EncodeCanonical(k)
-	if err != nil {
-		return "", err
-	}
-	digest := sha256.Sum256(canonical)
-	return hex.EncodeToString(digest[:]), nil
-}

signerverifier/test-data/rsa-test-key

@@ -0,0 +1,39 @@
+-----BEGIN RSA PRIVATE KEY-----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+w6gG/+YLvx9MYcEVGeruyPmlYFp6g+vN/qEiPs1oZej8r1XjNj228XdTMAJ2qTbZ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+-----END RSA PRIVATE KEY-----

signerverifier/test-data/rsa-test-key.pub

@@ -0,0 +1,11 @@
+-----BEGIN PUBLIC KEY-----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+-----END PUBLIC KEY-----