feat: define DWH installation credentials

2026-08-20 23:00:34 +02:00
parent 4ef0a6a833
commit 3bc84b0bc3
5 changed files with 452 additions and 0 deletions
@@ -0,0 +1,78 @@
+// Package credential generates and verifies DWH installation credentials.
+package credential
+
+import (
+	"crypto/sha256"
+	"crypto/subtle"
+	"encoding/base64"
+	"io"
+	"strings"
+
+	"github.com/aritmolab/thothii/tools/dwh-auth/internal/record"
+)
+
+const Prefix = "thtdwh_v1"
+const KeyIDEncodedLength = 16
+const SecretEncodedLength = 43
+const MaxHeaderBytes = 128
+
+type Material struct {
+	Value  []byte
+	KeyID  string
+	Digest record.Digest
+}
+
+// Generate creates one canonical version 1 credential from random.
+func Generate(random io.Reader) (Material, error) {
+	keyIDBytes := make([]byte, 12)
+	secretBytes := make([]byte, 32)
+	if _, err := io.ReadFull(random, keyIDBytes); err != nil {
+		return Material{}, err
+	}
+	if _, err := io.ReadFull(random, secretBytes); err != nil {
+		return Material{}, err
+	}
+	keyID := base64.RawURLEncoding.EncodeToString(keyIDBytes)
+	secret := base64.RawURLEncoding.EncodeToString(secretBytes)
+	value := []byte(Prefix + "." + keyID + "." + secret)
+	sum := sha256.Sum256(value)
+	return Material{Value: value, KeyID: keyID, Digest: record.Digest(sum)}, nil
+}
+
+// VerifyV1 authenticates one canonical version 1 credential and returns its key ID.
+func VerifyV1(value []byte, expected record.Digest) (string, bool) {
+	if len(value) > MaxHeaderBytes || len(value) != len(Prefix)+1+KeyIDEncodedLength+1+SecretEncodedLength {
+		return "", false
+	}
+	parts := strings.Split(string(value), ".")
+	if len(parts) != 3 || parts[0] != Prefix || !canonicalBase64(parts[1], 12, KeyIDEncodedLength) || !canonicalBase64(parts[2], 32, SecretEncodedLength) {
+		return "", false
+	}
+	sum := sha256.Sum256(value)
+	if subtle.ConstantTimeCompare(sum[:], expected[:]) != 1 {
+		return "", false
+	}
+	return parts[1], true
+}
+
+// VerifyLegacy authenticates an opaque legacy credential without interpreting its syntax.
+func VerifyLegacy(value []byte, expected record.Digest) bool {
+	if len(value) < 1 || len(value) > MaxHeaderBytes {
+		return false
+	}
+	for _, b := range value {
+		if b <= 0x1f || b == 0x7f {
+			return false
+		}
+	}
+	sum := sha256.Sum256(value)
+	return subtle.ConstantTimeCompare(sum[:], expected[:]) == 1
+}
+
+func canonicalBase64(value string, decodedLength, encodedLength int) bool {
+	if len(value) != encodedLength {
+		return false
+	}
+	decoded, err := base64.RawURLEncoding.DecodeString(value)
+	return err == nil && len(decoded) == decodedLength && base64.RawURLEncoding.EncodeToString(decoded) == value
+}
@@ -0,0 +1,116 @@
+package credential
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/base64"
+	"strings"
+	"testing"
+
+	"github.com/aritmolab/thothii/tools/dwh-auth/internal/record"
+)
+
+func TestGenerateProducesCanonicalV1Material(t *testing.T) {
+	random := bytes.NewReader(bytes.Repeat([]byte{0x7f}, 44))
+	material, err := Generate(random)
+	if err != nil {
+		t.Fatalf("Generate() error = %v", err)
+	}
+
+	if got, want := string(material.Value), "thtdwh_v1.f39_f39_f39_f39_.f39_f39_f39_f39_f39_f39_f39_f39_f39_f39_f38"; got != want {
+		t.Fatalf("Value = %q, want %q", got, want)
+	}
+	if got, want := len(material.Value), 70; got != want {
+		t.Fatalf("len(Value) = %d, want %d", got, want)
+	}
+	if got, want := material.KeyID, "f39_f39_f39_f39_"; got != want {
+		t.Fatalf("KeyID = %q, want %q", got, want)
+	}
+
+	segments := strings.Split(string(material.Value), ".")
+	if got, want := len(segments), 3; got != want {
+		t.Fatalf("segment count = %d, want %d", got, want)
+	}
+	if got, want := segments[0], Prefix; got != want {
+		t.Fatalf("prefix = %q, want %q", got, want)
+	}
+	if got, want := len(segments[1]), KeyIDEncodedLength; got != want {
+		t.Fatalf("key ID length = %d, want %d", got, want)
+	}
+	if got, want := len(segments[2]), SecretEncodedLength; got != want {
+		t.Fatalf("secret length = %d, want %d", got, want)
+	}
+	secret, err := base64.RawURLEncoding.DecodeString(segments[2])
+	if err != nil {
+		t.Fatalf("DecodeString(secret) error = %v", err)
+	}
+	if got, want := len(secret), 32; got != want {
+		t.Fatalf("decoded secret length = %d, want %d", got, want)
+	}
+
+	wantDigest := sha256.Sum256(material.Value)
+	if material.Digest != record.Digest(wantDigest) {
+		t.Fatalf("Digest = %x, want %x", material.Digest, wantDigest)
+	}
+}
+
+func TestVerifyV1AcceptsGeneratedMaterialAndRejectsChangedByte(t *testing.T) {
+	material, err := Generate(bytes.NewReader(bytes.Repeat([]byte{0x01}, 44)))
+	if err != nil {
+		t.Fatalf("Generate() error = %v", err)
+	}
+
+	if keyID, ok := VerifyV1(material.Value, material.Digest); !ok || keyID != material.KeyID {
+		t.Fatalf("VerifyV1() = (%q, %t), want (%q, true)", keyID, ok, material.KeyID)
+	}
+
+	changed := append([]byte(nil), material.Value...)
+	changed[len(changed)-1] ^= 1
+	if keyID, ok := VerifyV1(changed, material.Digest); ok || keyID != "" {
+		t.Fatalf("VerifyV1(changed) = (%q, %t), want (\"\", false)", keyID, ok)
+	}
+}
+
+func TestVerifyV1RejectsNonCanonicalValues(t *testing.T) {
+	material, err := Generate(bytes.NewReader(bytes.Repeat([]byte{0x02}, 44)))
+	if err != nil {
+		t.Fatalf("Generate() error = %v", err)
+	}
+
+	for _, value := range [][]byte{
+		append(append([]byte(nil), material.Value...), ','),
+		[]byte(string(material.Value) + "," + string(material.Value)),
+		[]byte(string(material.Value) + "." + material.KeyID),
+		[]byte(string(material.Value) + "="),
+		[]byte(" " + string(material.Value)),
+		append(bytes.Repeat([]byte{'a'}, MaxHeaderBytes+1)),
+	} {
+		if keyID, ok := VerifyV1(value, material.Digest); ok || keyID != "" {
+			t.Fatalf("VerifyV1(%q) = (%q, %t), want (\"\", false)", value, keyID, ok)
+		}
+	}
+}
+
+func TestVerifyLegacyHashesOpaqueRawValueWithoutV1Parsing(t *testing.T) {
+	value := []byte("legacy opaque value /:[]")
+	sum := sha256.Sum256(value)
+	if !VerifyLegacy(value, record.Digest(sum)) {
+		t.Fatal("VerifyLegacy() = false, want true")
+	}
+	if VerifyLegacy([]byte("thtdwh_v1.not-a-valid-v1"), record.Digest(sum)) {
+		t.Fatal("VerifyLegacy() accepted a different raw value")
+	}
+}
+
+func TestVerifyLegacyRejectsInvalidOpaqueValues(t *testing.T) {
+	sum := sha256.Sum256([]byte("legacy"))
+	for _, value := range [][]byte{
+		nil,
+		bytes.Repeat([]byte{'a'}, MaxHeaderBytes+1),
+		[]byte("bad\nvalue"),
+	} {
+		if VerifyLegacy(value, record.Digest(sum)) {
+			t.Fatalf("VerifyLegacy(%q) = true, want false", value)
+		}
+	}
+}