Рыба проекта. Минимальная функциональность

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2026-08-03 22:22:24 +03:00
commit 8c8631ac9c
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package composite
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"crypto/sha256"
"encoding/base64"
"encoding/binary"
"encoding/json"
"errors"
"fmt"
"io"
"os"
"testing"
"git.tswf.io/infra/go-synapse-backupper/pkg/domain/crypto"
)
// ---------------------------------------------------------------------------
// Test KEM harness
//
// The composite format pins slot 0 = PQ (schemeID 0x0006, ciphertext length
// 1088) and slot 1 = classical (schemeID 0x0007, ciphertext length 32),
// matching the real mlkem768 + x25519 adapter contracts. Adapters' priv types
// are unexported and reject type-asserted impostors at Decapsulate, and the
// composite todo's scope forbids touching adapter packages — so tests exercise
// the composite with deterministic fake KEMs (registered under the SAME
// schemeIDs as the real adapters). The committed golden fixture uses these
// fakes; the composite production code is exercised end-to-end on the format,
// the HKDF combiner, AES-256-GCM wrapping, and chunked AEAD.
// ---------------------------------------------------------------------------
const (
fakePqSchemeID uint16 = 0x0006
fakeClassicalSchemeID uint16 = 0x0007
fakePqCtLen int = 1088 // matches crypto/mlkem EncapsulateKey768 ciphertext length
fakeClassicalCtLen int = 32 // matches X25519 ephemeral pubkey length
fakeSeedLen int = 32
)
// fakeKem derives a deterministic shared secret per pub/ct pair:
//
// ss = SHA256(pub_raw_or_priv_raw || ct)
//
// where pub.raw and priv.raw are both the random seed; randomness lives only
// in the ct (the call site's rand supplies ct bytes), so decapsulation with
// the matching priv always recovers the encryption-time ss.
type fakeKem struct {
schemeIDValue uint16
ctLenValue int
}
func newFakePqKem() crypto.KEM {
return &fakeKem{schemeIDValue: fakePqSchemeID, ctLenValue: fakePqCtLen}
}
func newFakeClassicalKem() crypto.KEM {
return &fakeKem{schemeIDValue: fakeClassicalSchemeID, ctLenValue: fakeClassicalCtLen}
}
func (k *fakeKem) SchemeID() uint16 { return k.schemeIDValue }
func (k *fakeKem) GenerateKeyPair(
rand io.Reader,
) (
crypto.RecipientPub,
crypto.RecipientPriv,
error,
) {
seed := make([]byte, fakeSeedLen)
if _, err := io.ReadFull(rand, seed); err != nil {
return nil, nil, err
}
return newFakePub(k.schemeIDValue, seed), newFakePriv(k.schemeIDValue, seed), nil
}
func (k *fakeKem) Encapsulate(
pub crypto.RecipientPub,
rand io.Reader,
) (
ciphertext []byte,
sharedSecret []byte,
err error,
) {
p, ok := pub.(*fakePub)
if !ok {
return nil, nil, errors.New("fakeKem: invalid pub type")
}
ciphertext = make([]byte, k.ctLenValue)
if _, err := io.ReadFull(rand, ciphertext); err != nil {
return nil, nil, err
}
return ciphertext, deriveFakeSS(p.raw, ciphertext), nil
}
func (k *fakeKem) Decapsulate(
priv crypto.RecipientPriv,
ciphertext []byte,
) (
sharedSecret []byte,
err error,
) {
p, ok := priv.(*fakePriv)
if !ok {
return nil, errors.New("fakeKem: invalid priv type")
}
if len(ciphertext) != k.ctLenValue {
return nil, errors.New("fakeKem: invalid ciphertext length")
}
return deriveFakeSS(p.raw, ciphertext), nil
}
func (k *fakeKem) LoadPriv(
raw []byte,
) (
crypto.RecipientPriv,
error,
) {
return newFakePriv(k.schemeIDValue, raw), nil
}
func deriveFakeSS(
raw, ciphertext []byte,
) []byte {
h := sha256.New()
h.Write(raw)
h.Write(ciphertext)
return h.Sum(nil)
}
// fakePub / fakePriv — deterministic raw-bytes-backed recipients.
type fakePub struct {
scheme uint16
raw []byte
keyID []byte
}
func newFakePub(
scheme uint16,
raw []byte,
) *fakePub {
h := sha256.Sum256(raw)
return &fakePub{
scheme: scheme,
raw: append([]byte(nil), raw...),
keyID: h[:8],
}
}
func (f *fakePub) SchemeID() uint16 { return f.scheme }
func (f *fakePub) KeyID() []byte { return f.keyID }
func (f *fakePub) Raw() []byte { return f.raw }
type fakePriv struct {
scheme uint16
raw []byte
keyID []byte
}
func newFakePriv(
scheme uint16,
raw []byte,
) *fakePriv {
h := sha256.Sum256(raw)
return &fakePriv{
scheme: scheme,
raw: append([]byte(nil), raw...),
keyID: h[:8],
}
}
func (f *fakePriv) SchemeID() uint16 { return f.scheme }
func (f *fakePriv) KeyID() []byte { return f.keyID }
func (f *fakePriv) Raw() []byte { return f.raw }
// fakeRegistry returns a Registry with the two fake KEMs registered under
// the v2 slot schemeIDs.
func fakeRegistry(
t *testing.T,
) crypto.Registry {
t.Helper()
reg := crypto.NewRegistry()
if err := reg.Register(fakePqSchemeID, newFakePqKem); err != nil {
t.Fatalf("register pq fake: %v", err)
}
if err := reg.Register(fakeClassicalSchemeID, newFakeClassicalKem); err != nil {
t.Fatalf("register classical fake: %v", err)
}
return reg
}
// generateFakeKeyPair generates (pub, priv) for slot schemeID from rand.
func generateFakeKeyPair(
t *testing.T,
reg crypto.Registry,
schemeID uint16,
rand io.Reader,
) (
crypto.RecipientPub,
crypto.RecipientPriv,
) {
t.Helper()
factory, err := reg.Lookup(schemeID)
if err != nil {
t.Fatalf("lookup 0x%04x: %v", schemeID, err)
}
pub, priv, err := factory().GenerateKeyPair(rand)
if err != nil {
t.Fatalf("generate 0x%04x: %v", schemeID, err)
}
return pub, priv
}
// standardHeaderLen returns the fixed artifact-header length given the two
// slot ciphertext lengths: 11 (magic+version+flags+nRecipients) +
// per-slot (14 + ctLen) + 72 (wrapNonce+wrappedCEK+firstPayloadNonce).
func standardHeaderLen(
pqCtLen, classicalCtLen int,
) int {
return 11 + (14 + pqCtLen) + (14 + classicalCtLen) + (12 + 48 + 12)
}
// countingReader wraps an io.Reader and counts how many bytes have been read
// — used by the adversarial-parser tests to assert the parser does NOT
// consume past the header before bailing out.
type countingReader struct {
r io.Reader
n int64
}
func (c *countingReader) Read(
p []byte,
) (int, error) {
readN, err := c.r.Read(p)
c.n += int64(readN)
return readN, err
}
// ---------------------------------------------------------------------------
// Tests (a) through (p)
// ---------------------------------------------------------------------------
// (a) Golden format fixture.
func TestGoldenFormat(
t *testing.T,
) {
goldenBytes := mustReadFile(t, "testdata/golden-1byte.pqenc")
// Header byte offsets pinned verbatim — if any of these breaks, the
// on-disk format has drifted and old .pqenc files won't decrypt.
// [0:4] magic u32 BE = 0x47535051
// [4:6] version u16 BE = 0x0002
// [6:10] flags u32 BE = 0x00000000
// [10] nRecipients u8 = 0x02
// [11:13] slot0 schemeID = 0x0006
// [13:21] slot0 keyID 8B
// [21:25] slot0 ctLen u32 = 1088
// [25:1113] slot0 ciphertext (1088 bytes)
// [1113:1115] slot1 schemeID = 0x0007
if binary.BigEndian.Uint32(goldenBytes[0:4]) != 0x47535051 {
t.Errorf("magic = 0x%08x, want 0x47535051", binary.BigEndian.Uint32(goldenBytes[0:4]))
}
if binary.BigEndian.Uint16(goldenBytes[4:6]) != 0x0002 {
t.Errorf("version = 0x%04x, want 0x0002", binary.BigEndian.Uint16(goldenBytes[4:6]))
}
if binary.BigEndian.Uint32(goldenBytes[6:10]) != 0x00000000 {
t.Errorf("flags = 0x%08x, want 0", binary.BigEndian.Uint32(goldenBytes[6:10]))
}
if goldenBytes[10] != 0x02 {
t.Errorf("nRecipients = 0x%02x, want 0x02", goldenBytes[10])
}
if binary.BigEndian.Uint16(goldenBytes[11:13]) != 0x0006 {
t.Errorf("slot0 schemeID = 0x%04x, want 0x0006", binary.BigEndian.Uint16(goldenBytes[11:13]))
}
if binary.BigEndian.Uint16(goldenBytes[1113:1115]) != 0x0007 {
t.Errorf("slot1 schemeID = 0x%04x, want 0x0007", binary.BigEndian.Uint16(goldenBytes[1113:1115]))
}
// Decrypt-equality: reconstruct privs from committed golden-keys.json
// and assert Decrypt yields the 0xAA plaintext committed via golden_generate.
pqPriv, classicalPriv := loadGoldenPrivs(t, "testdata/golden-keys.json")
dec := NewDecryptor(fakeRegistry(t))
out := &bytes.Buffer{}
if err := dec.Decrypt(
bytes.NewReader(goldenBytes),
[]crypto.RecipientPriv{pqPriv, classicalPriv},
out,
); err != nil {
t.Fatalf("Decrypt(golden) failed: %v", err)
}
if !bytes.Equal(out.Bytes(), []byte{0xAA}) {
t.Errorf("decrypted = %x, want [0xAA]", out.Bytes())
}
}
// (b) Round-trip on canonical input sizes.
func TestRoundTrip(
t *testing.T,
) {
sizes := []int{0, 1, 64*1024 - 1, 64 * 1024, 64*1024 + 1, 1 << 20}
for _, size := range sizes {
t.Run(fmt.Sprintf("size=%d", size), func(t *testing.T) {
plaintext := make([]byte, size)
for i := 0; i < size; i++ {
plaintext[i] = byte(i)
}
reg := fakeRegistry(t)
enc := NewEncryptor(reg)
dec := NewDecryptor(reg)
pqPub, pqPriv := generateFakeKeyPair(t, reg, fakePqSchemeID, rand.Reader)
classicalPub, classicalPriv := generateFakeKeyPair(t, reg, fakeClassicalSchemeID, rand.Reader)
var encrypted bytes.Buffer
if err := enc.Encrypt(
bytes.NewReader(plaintext),
[]crypto.RecipientPub{pqPub, classicalPub},
&encrypted,
rand.Reader,
); err != nil {
t.Fatalf("Encrypt: %v", err)
}
out := &bytes.Buffer{}
if err := dec.Decrypt(
bytes.NewReader(encrypted.Bytes()),
[]crypto.RecipientPriv{pqPriv, classicalPriv},
out,
); err != nil {
t.Fatalf("Decrypt: %v", err)
}
if !bytes.Equal(out.Bytes(), plaintext) {
t.Errorf("round-trip mismatch: got %d bytes, want %d", out.Len(), len(plaintext))
}
})
}
}
// (c) Empty plaintext produces exactly ONE chunk with flags=0x01 and a 16B
// (tag-only) ciphertext.
func TestEmptyPlaintextSingleFinalChunk(
t *testing.T,
) {
reg := fakeRegistry(t)
enc := NewEncryptor(reg)
pqPub, _ := generateFakeKeyPair(t, reg, fakePqSchemeID, rand.Reader)
classicalPub, _ := generateFakeKeyPair(t, reg, fakeClassicalSchemeID, rand.Reader)
var encrypted bytes.Buffer
if err := enc.Encrypt(
bytes.NewReader(nil),
[]crypto.RecipientPub{pqPub, classicalPub},
&encrypted,
rand.Reader,
); err != nil {
t.Fatalf("Encrypt: %v", err)
}
headerLen := standardHeaderLen(fakePqCtLen, fakeClassicalCtLen)
chunks := encrypted.Bytes()[headerLen:]
// Expected record: [len=16 u32 (4B)][flags=0x01 (1B)][ciphertext (16B)].
if len(chunks) != 4+1+16 {
t.Fatalf("expected 21-byte chunk record, got %d bytes", len(chunks))
}
if ctLen := binary.BigEndian.Uint32(chunks[0:4]); ctLen != 16 {
t.Errorf("ctLen = %d, want 16 (tag-only)", ctLen)
}
if chunks[4] != 0x01 {
t.Errorf("flags = 0x%02x, want 0x01", chunks[4])
}
if len(chunks[5:]) != 16 {
t.Errorf("ciphertext = %d bytes, want 16 (tag-only)", len(chunks[5:]))
}
}
// (d) Exactly-64KiB input produces TWO chunks: full body (flags=0x00) and
// zero-length final marker (flags=0x01).
func TestExactly64KiBTwoChunks(
t *testing.T,
) {
reg := fakeRegistry(t)
enc := NewEncryptor(reg)
pqPub, _ := generateFakeKeyPair(t, reg, fakePqSchemeID, rand.Reader)
classicalPub, _ := generateFakeKeyPair(t, reg, fakeClassicalSchemeID, rand.Reader)
plaintext := bytes.Repeat([]byte{0xCC}, 64*1024)
var encrypted bytes.Buffer
if err := enc.Encrypt(
bytes.NewReader(plaintext),
[]crypto.RecipientPub{pqPub, classicalPub},
&encrypted,
rand.Reader,
); err != nil {
t.Fatalf("Encrypt: %v", err)
}
headerLen := standardHeaderLen(fakePqCtLen, fakeClassicalCtLen)
chunks := encrypted.Bytes()[headerLen:]
// Chunk 1: full body. ct = 64 KiB plaintext + 16B tag.
const bodyCtLen = 64*1024 + 16
if ctLen := binary.BigEndian.Uint32(chunks[0:4]); ctLen != bodyCtLen {
t.Errorf("chunk1 ctLen = %d, want %d", ctLen, bodyCtLen)
}
if chunks[4] != 0x00 {
t.Errorf("chunk1 flags = 0x%02x, want 0x00", chunks[4])
}
// Chunk 2: zero-length final marker (ct = 16B tag), flags = 0x01.
chunk2Start := 4 + 1 + bodyCtLen
if chunk2Start+5 > len(chunks) {
t.Fatalf("file truncated before chunk 2: need offset %d, have %d", chunk2Start+5, len(chunks))
}
if ctLen := binary.BigEndian.Uint32(chunks[chunk2Start : chunk2Start+4]); ctLen != 16 {
t.Errorf("chunk2 ctLen = %d, want 16 (zero-length marker)", ctLen)
}
if chunks[chunk2Start+4] != 0x01 {
t.Errorf("chunk2 flags = 0x%02x, want 0x01", chunks[chunk2Start+4])
}
chunk3Start := chunk2Start + 4 + 1 + 16
if chunk3Start != len(chunks) {
t.Errorf("expected exactly 2 chunks; remaining = %d bytes after chunk 2", len(chunks)-chunk3Start)
}
}
// (e) Counter wrap-around: with chunkNonce[4:12]=0xFFFFFFFFFFFFFFFF, an
// attempt to encrypt a SECOND body chunk fails on counter increment and
// returns ErrNonceCounterWrapped.
func TestCounterWraparound(
t *testing.T,
) {
// firstPayloadNonce: slot 0..3 = arbitrary base; slot 4..11 = 0xFF*8.
firstPayloadNonce := make([]byte, 12)
firstPayloadNonce[0] = 0xde
firstPayloadNonce[1] = 0xad
firstPayloadNonce[2] = 0xbe
firstPayloadNonce[3] = 0xef
for i := 4; i < 12; i++ {
firstPayloadNonce[i] = 0xFF
}
cek := make([]byte, 32)
if _, err := io.ReadFull(rand.Reader, cek); err != nil {
t.Fatalf("rand: %v", err)
}
block, err := aes.NewCipher(cek)
if err != nil {
t.Fatalf("aes: %v", err)
}
gcm, err := cipher.NewGCM(block)
if err != nil {
t.Fatalf("gcm: %v", err)
}
// 64 KiB + 1 byte forces 2 body chunks; incrementing after chunk 1
// wraps to 0 and ErrNonceCounterWrapped (the second chunk's emission
// never happens).
input := make([]byte, chunkSize+1)
var out bytes.Buffer
err = encryptChunks(bytes.NewReader(input), &out, gcm, firstPayloadNonce)
if !errors.Is(err, ErrNonceCounterWrapped) {
t.Errorf("expected ErrNonceCounterWrapped, got %v", err)
}
}
// (f) Tamper 1 byte in payload → ErrTamperingDetected.
func TestTamperPayload(
t *testing.T,
) {
reg := fakeRegistry(t)
enc := NewEncryptor(reg)
dec := NewDecryptor(reg)
pqPub, pqPriv := generateFakeKeyPair(t, reg, fakePqSchemeID, rand.Reader)
classicalPub, classicalPriv := generateFakeKeyPair(t, reg, fakeClassicalSchemeID, rand.Reader)
plaintext := bytes.Repeat([]byte{0x88}, 64*1024+1) // enough to produce a body chunk + final
var encrypted bytes.Buffer
if err := enc.Encrypt(
bytes.NewReader(plaintext),
[]crypto.RecipientPub{pqPub, classicalPub},
&encrypted,
rand.Reader,
); err != nil {
t.Fatalf("Encrypt: %v", err)
}
buf := encrypted.Bytes()
headerLen := standardHeaderLen(fakePqCtLen, fakeClassicalCtLen)
tamperIdx := headerLen + 4 + 1 + 8 // into first chunk ciphertext, past len + flags
if tamperIdx >= len(buf) {
t.Fatalf("file too small to tamper: idx=%d len=%d", tamperIdx, len(buf))
}
buf[tamperIdx] ^= 0x01
out := &bytes.Buffer{}
err := dec.Decrypt(
bytes.NewReader(buf),
[]crypto.RecipientPriv{pqPriv, classicalPriv},
out,
)
if !errors.Is(err, ErrTamperingDetected) {
t.Errorf("expected ErrTamperingDetected, got %v", err)
}
}
// (g) Tamper 1 byte in wrappedCEK → ErrTamperingDetected.
func TestTamperWrappedCEK(
t *testing.T,
) {
reg := fakeRegistry(t)
enc := NewEncryptor(reg)
dec := NewDecryptor(reg)
pqPub, pqPriv := generateFakeKeyPair(t, reg, fakePqSchemeID, rand.Reader)
classicalPub, classicalPriv := generateFakeKeyPair(t, reg, fakeClassicalSchemeID, rand.Reader)
var encrypted bytes.Buffer
if err := enc.Encrypt(
bytes.NewReader([]byte{0xAA}),
[]crypto.RecipientPub{pqPub, classicalPub},
&encrypted,
rand.Reader,
); err != nil {
t.Fatalf("Encrypt: %v", err)
}
buf := encrypted.Bytes()
// wrappedCEK starts at: header-prefix (11) + slot0 (+ct) + slot1 (+ct) + wrapNonce (12).
wrapOffset := 11 + (14 + fakePqCtLen) + (14 + fakeClassicalCtLen) + 12
if wrapOffset+wrappedCekLen > len(buf) {
t.Fatalf("file too short for wrappedCEK")
}
buf[wrapOffset+5] ^= 0x01
out := &bytes.Buffer{}
err := dec.Decrypt(
bytes.NewReader(buf),
[]crypto.RecipientPriv{pqPriv, classicalPriv},
out,
)
if !errors.Is(err, ErrTamperingDetected) {
t.Errorf("expected ErrTamperingDetected, got %v", err)
}
}
// (h) Wrong priv key (swap pq.priv with another) → ErrWrongKeys.
func TestWrongPrivKey(
t *testing.T,
) {
reg := fakeRegistry(t)
enc := NewEncryptor(reg)
dec := NewDecryptor(reg)
pqPub, _ := generateFakeKeyPair(t, reg, fakePqSchemeID, rand.Reader)
classicalPub, classicalPriv := generateFakeKeyPair(t, reg, fakeClassicalSchemeID, rand.Reader)
// Different PQ priv — fresh seed, hence different KeyID.
_, wrongPqPriv := generateFakeKeyPair(t, reg, fakePqSchemeID, rand.Reader)
// Sanity: the wrong priv's keyID must not collide with the original
// pub's (otherwise this test would degrade into a keyID-collision case).
if bytes.Equal(wrongPqPriv.KeyID(), pqPub.KeyID()) {
t.Fatalf("wrongPqPriv keyID accidentally collides with pqPub keyID; reseed")
}
var encrypted bytes.Buffer
if err := enc.Encrypt(
bytes.NewReader([]byte{0x11, 0x22, 0x33}),
[]crypto.RecipientPub{pqPub, classicalPub},
&encrypted,
rand.Reader,
); err != nil {
t.Fatalf("Encrypt: %v", err)
}
out := &bytes.Buffer{}
err := dec.Decrypt(
bytes.NewReader(encrypted.Bytes()),
[]crypto.RecipientPriv{wrongPqPriv, classicalPriv},
out,
)
if !errors.Is(err, ErrWrongKeys) {
t.Errorf("expected ErrWrongKeys, got %v", err)
}
}
// (i) Format conformance: magic, version, nRecipients.
func TestFormatConformance(
t *testing.T,
) {
reg := fakeRegistry(t)
enc := NewEncryptor(reg)
pqPub, _ := generateFakeKeyPair(t, reg, fakePqSchemeID, rand.Reader)
classicalPub, _ := generateFakeKeyPair(t, reg, fakeClassicalSchemeID, rand.Reader)
var out bytes.Buffer
if err := enc.Encrypt(
bytes.NewReader([]byte{0x42}),
[]crypto.RecipientPub{pqPub, classicalPub},
&out,
rand.Reader,
); err != nil {
t.Fatalf("Encrypt: %v", err)
}
outBytes := out.Bytes()
if binary.BigEndian.Uint32(outBytes[0:4]) != 0x47535051 {
t.Errorf("magic = 0x%08x, want 0x47535051", binary.BigEndian.Uint32(outBytes[0:4]))
}
if binary.BigEndian.Uint16(outBytes[4:6]) != 0x0002 {
t.Errorf("version = 0x%04x, want 0x0002", binary.BigEndian.Uint16(outBytes[4:6]))
}
if outBytes[10] != 0x02 {
t.Errorf("nRecipients = 0x%02x, want 0x02", outBytes[10])
}
}
// (j) Adversarial parser: version==0x0001 → ErrUnsupportedVersion, with no
// GCM operations attempted (proven by the post-validation byte counter
// remaining at the prefix length — the parser does not consume past the
// header before bailing).
func TestUnsupportedVersionNoGCM(
t *testing.T,
) {
reg := fakeRegistry(t)
dec := NewDecryptor(reg)
// File: magic + version=0x0001 + flags + nRecipients=0x02 + filler.
var buf bytes.Buffer
_ = binary.Write(&buf, binary.BigEndian, uint32(0x47535051)) // magic
_ = binary.Write(&buf, binary.BigEndian, uint16(0x0001)) // version (downgrade probe)
buf.Write(make([]byte, 200)) // filler
// Dummy privs — irrelevant because the parser bails at version check,
// but Decrypt accepts the slice shape.
_, pqPriv := generateFakeKeyPair(t, reg, fakePqSchemeID, rand.Reader)
_, classicalPriv := generateFakeKeyPair(t, reg, fakeClassicalSchemeID, rand.Reader)
reader := &countingReader{r: bytes.NewReader(buf.Bytes())}
out := &bytes.Buffer{}
err := dec.Decrypt(
reader,
[]crypto.RecipientPriv{pqPriv, classicalPriv},
out,
)
if !errors.Is(err, ErrUnsupportedVersion) {
t.Errorf("expected ErrUnsupportedVersion, got %v", err)
}
// The parser consumed only the 11-byte prefix — no further bytes read,
// hence no GCM operations attempted.
if reader.n != 11 {
t.Errorf("Decrypt consumed %d bytes post-validation; expected exactly 11 (the fixed prefix)", reader.n)
}
}
// (k) nRecipients==0 → ErrMalformedHeader.
func TestZeroRecipients(
t *testing.T,
) {
var buf bytes.Buffer
_ = binary.Write(&buf, binary.BigEndian, uint32(0x47535051)) // magic
_ = binary.Write(&buf, binary.BigEndian, uint16(0x0002)) // version
_ = binary.Write(&buf, binary.BigEndian, uint32(0)) // flags
buf.WriteByte(0x00) // nRecipients = 0
buf.Write(make([]byte, 64)) // filler
dec := NewDecryptor(fakeRegistry(t))
err := dec.Decrypt(bytes.NewReader(buf.Bytes()), nil, &bytes.Buffer{})
if !errors.Is(err, ErrMalformedHeader) {
t.Errorf("expected ErrMalformedHeader, got %v", err)
}
}
// (l) nRecipients>2 OR ctLen > maxRecipientCiphertextLen →
// ErrMalformedHeader BEFORE io.ReadFull attempts to allocate the
// oversized ciphertext buffer.
func TestMalformedHeaderCtLenOverflow(
t *testing.T,
) {
t.Run("nRecipients_gt_2", func(t *testing.T) {
var buf bytes.Buffer
_ = binary.Write(&buf, binary.BigEndian, uint32(0x47535051)) // magic
_ = binary.Write(&buf, binary.BigEndian, uint16(0x0002)) // version
_ = binary.Write(&buf, binary.BigEndian, uint32(0)) // flags
buf.WriteByte(0x03) // nRecipients = 3
buf.Write(make([]byte, 200)) // filler
dec := NewDecryptor(fakeRegistry(t))
err := dec.Decrypt(bytes.NewReader(buf.Bytes()), nil, &bytes.Buffer{})
if !errors.Is(err, ErrMalformedHeader) {
t.Errorf("expected ErrMalformedHeader, got %v", err)
}
})
t.Run("ctLen_overflow", func(t *testing.T) {
var buf bytes.Buffer
_ = binary.Write(&buf, binary.BigEndian, uint32(0x47535051)) // magic
_ = binary.Write(&buf, binary.BigEndian, uint16(0x0002)) // version
_ = binary.Write(&buf, binary.BigEndian, uint32(0)) // flags
buf.WriteByte(0x02) // nRecipients = 2
// Slot 0 metadata only — schemeID, keyID, ctLen = 2 MiB (over the
// 1<<20 cap). The parser validates ctLen BEFORE allocating and
// reading per-slot ciphertext bytes, so it must reject at this
// point without attempting io.ReadFull of an oversized buffer.
_ = binary.Write(&buf, binary.BigEndian, uint16(0x0006))
buf.Write(make([]byte, 8)) // keyID
_ = binary.Write(&buf, binary.BigEndian, uint32(2*1024*1024)) // ctLen
reader := &countingReader{r: bytes.NewReader(buf.Bytes())}
dec := NewDecryptor(fakeRegistry(t))
_, pqPriv := generateFakeKeyPair(t, fakeRegistry(t), fakePqSchemeID, rand.Reader)
_, classicalPriv := generateFakeKeyPair(t, fakeRegistry(t), fakeClassicalSchemeID, rand.Reader)
err := dec.Decrypt(
reader,
[]crypto.RecipientPriv{pqPriv, classicalPriv},
&bytes.Buffer{},
)
if !errors.Is(err, ErrMalformedHeader) {
t.Errorf("expected ErrMalformedHeader, got %v", err)
}
// Consumed exactly prefix(11) + slot0 metadata(14) = 25 bytes — the
// ctLen validation fired before reading any slot1 metadata or any
// per-slot ciphertext.
if reader.n != 25 {
t.Errorf("Decrypt consumed %d bytes; expected 25 (no io.ReadFull of oversized ct)", reader.n)
}
})
}
// (m) Chunk record with length==0 AND flags&0x01==0 → ErrMalformedChunk
// (prevents an infinite-loop DoS where the parser keeps scanning zero-size
// non-final chunks).
func TestZeroLengthNonFinalChunk(
t *testing.T,
) {
reg := fakeRegistry(t)
enc := NewEncryptor(reg)
dec := NewDecryptor(reg)
pqPub, pqPriv := generateFakeKeyPair(t, reg, fakePqSchemeID, rand.Reader)
classicalPub, classicalPriv := generateFakeKeyPair(t, reg, fakeClassicalSchemeID, rand.Reader)
var encrypted bytes.Buffer
if err := enc.Encrypt(
bytes.NewReader([]byte{0xAA}),
[]crypto.RecipientPub{pqPub, classicalPub},
&encrypted,
rand.Reader,
); err != nil {
t.Fatalf("Encrypt: %v", err)
}
headerLen := standardHeaderLen(fakePqCtLen, fakeClassicalCtLen)
var corrupt bytes.Buffer
corrupt.Write(encrypted.Bytes()[:headerLen])
_ = binary.Write(&corrupt, binary.BigEndian, uint32(0)) // ctLen = 0
corrupt.WriteByte(0x00) // flags = 0x00 (NOT final)
out := &bytes.Buffer{}
err := dec.Decrypt(
bytes.NewReader(corrupt.Bytes()),
[]crypto.RecipientPriv{pqPriv, classicalPriv},
out,
)
if !errors.Is(err, ErrMalformedChunk) {
t.Errorf("expected ErrMalformedChunk, got %v", err)
}
}
// (n) Chunk record with length > 64*1024+16 → ErrMalformedChunk.
func TestOversizedChunk(
t *testing.T,
) {
reg := fakeRegistry(t)
enc := NewEncryptor(reg)
dec := NewDecryptor(reg)
pqPub, pqPriv := generateFakeKeyPair(t, reg, fakePqSchemeID, rand.Reader)
classicalPub, classicalPriv := generateFakeKeyPair(t, reg, fakeClassicalSchemeID, rand.Reader)
var encrypted bytes.Buffer
if err := enc.Encrypt(
bytes.NewReader([]byte{0xAA}),
[]crypto.RecipientPub{pqPub, classicalPub},
&encrypted,
rand.Reader,
); err != nil {
t.Fatalf("Encrypt: %v", err)
}
headerLen := standardHeaderLen(fakePqCtLen, fakeClassicalCtLen)
var corrupt bytes.Buffer
corrupt.Write(encrypted.Bytes()[:headerLen])
_ = binary.Write(&corrupt, binary.BigEndian, uint32(chunkSize+gcmTagLen+1)) // oversized
corrupt.WriteByte(0x00) // flags = 0x00
out := &bytes.Buffer{}
err := dec.Decrypt(
bytes.NewReader(corrupt.Bytes()),
[]crypto.RecipientPriv{pqPriv, classicalPriv},
out,
)
if !errors.Is(err, ErrMalformedChunk) {
t.Errorf("expected ErrMalformedChunk, got %v", err)
}
}
// (o) End-of-stream reached BEFORE any chunk with flags&0x01==1
// (truncated file after a body chunk with no final marker) →
// ErrUnexpectedEOF.
func TestPrematureEOF(
t *testing.T,
) {
reg := fakeRegistry(t)
enc := NewEncryptor(reg)
dec := NewDecryptor(reg)
pqPub, pqPriv := generateFakeKeyPair(t, reg, fakePqSchemeID, rand.Reader)
classicalPub, classicalPriv := generateFakeKeyPair(t, reg, fakeClassicalSchemeID, rand.Reader)
plaintext := bytes.Repeat([]byte{0xAB}, 64*1024+1) // 2 body chunks + final marker
var encrypted bytes.Buffer
if err := enc.Encrypt(
bytes.NewReader(plaintext),
[]crypto.RecipientPub{pqPub, classicalPub},
&encrypted,
rand.Reader,
); err != nil {
t.Fatalf("Encrypt: %v", err)
}
headerLen := standardHeaderLen(fakePqCtLen, fakeClassicalCtLen)
bodyCtLen := 64*1024 + 1 + gcmTagLen
bodyChunkRecord := 4 + 1 + bodyCtLen
truncatedLen := headerLen + bodyChunkRecord
if truncatedLen >= len(encrypted.Bytes()) {
t.Fatalf("encrypted file shorter than expected: %d vs expected truncation at %d",
len(encrypted.Bytes()), truncatedLen)
}
out := &bytes.Buffer{}
err := dec.Decrypt(
bytes.NewReader(encrypted.Bytes()[:truncatedLen]),
[]crypto.RecipientPriv{pqPriv, classicalPriv},
out,
)
if !errors.Is(err, ErrUnexpectedEOF) {
t.Errorf("expected ErrUnexpectedEOF, got %v", err)
}
}
// (p) Truncated header → ErrMalformedHeader BEFORE any recipient allocation.
func TestTruncatedHeader(
t *testing.T,
) {
dec := NewDecryptor(fakeRegistry(t))
// File is shorter than the fixed 11-byte prefix + per-recipient metadata
// (2×14=28 = 39 bytes minimum): only 30 bytes total.
var buf bytes.Buffer
_ = binary.Write(&buf, binary.BigEndian, uint32(0x47535051)) // magic
_ = binary.Write(&buf, binary.BigEndian, uint16(0x0002)) // version
_ = binary.Write(&buf, binary.BigEndian, uint32(0)) // flags
buf.WriteByte(0x02) // nRecipients = 2
buf.Write(make([]byte, 20)) // only 20 of the needed 28 metadata bytes
reader := &countingReader{r: bytes.NewReader(buf.Bytes())}
err := dec.Decrypt(reader, nil, &bytes.Buffer{})
if !errors.Is(err, ErrMalformedHeader) {
t.Errorf("expected ErrMalformedHeader, got %v", err)
}
// No recipient ct allocation happened — only the prefix (11) + partial
// metadata (20) = 31 bytes consumed; well shy of a full prefix+meta
// read that would precede any per-recipient ct allocation.
if reader.n > 39 {
t.Errorf("Decrypt consumed %d bytes; expected ≤ 39 — no recipient allocation occurred", reader.n)
}
}
// ---------------------------------------------------------------------------
// Shared test helpers
// ---------------------------------------------------------------------------
func mustReadFile(
t *testing.T,
path string,
) []byte {
t.Helper()
data, err := os.ReadFile(path)
if err != nil {
t.Fatalf("read %s: %v", path, err)
}
return data
}
func mustB64Decode(
t *testing.T,
s string,
) []byte {
t.Helper()
b, err := base64.StdEncoding.DecodeString(s)
if err != nil {
t.Fatalf("base64 decode: %v", err)
}
return b
}
// loadGoldenPrivs reconstructs the two fake privs from the committed
// golden-keys.json (the file produced by //go:build golden_generate).
type goldenKeyFile struct {
Pq string `json:"pq"`
Classical string `json:"classical"`
}
func loadGoldenPrivs(
t *testing.T,
path string,
) (
*fakePriv,
*fakePriv,
) {
t.Helper()
data := mustReadFile(t, path)
var keys goldenKeyFile
if err := json.Unmarshal(data, &keys); err != nil {
t.Fatalf("unmarshal golden keys: %v", err)
}
pqRaw := mustB64Decode(t, keys.Pq)
classicalRaw := mustB64Decode(t, keys.Classical)
if len(pqRaw) != fakeSeedLen {
t.Fatalf("pq raw len = %d, want %d", len(pqRaw), fakeSeedLen)
}
if len(classicalRaw) != fakeSeedLen {
t.Fatalf("classical raw len = %d, want %d", len(classicalRaw), fakeSeedLen)
}
return newFakePriv(fakePqSchemeID, pqRaw), newFakePriv(fakeClassicalSchemeID, classicalRaw)
}