|
| 1 | +package cose |
| 2 | + |
| 3 | +import ( |
| 4 | + "bytes" |
| 5 | + "io" |
| 6 | + "testing" |
| 7 | + "testing/iotest" |
| 8 | + |
| 9 | + "github.com/stretchr/testify/require" |
| 10 | +) |
| 11 | + |
| 12 | +// TestDecodeReader exercises the streaming decoder: it decodes both envelope |
| 13 | +// forms off a reader, streams back the detached ciphertext that follows the |
| 14 | +// header, and — critically — produces the same Enc_structure (AAD) and the same |
| 15 | +// trailing bytes as the byte-based Decode, so a caller can decrypt an envelope |
| 16 | +// read either way. |
| 17 | +func TestDecodeReader(t *testing.T) { |
| 18 | + ciphertext := []byte("detached-stream-ciphertext-bytes-0123456789") |
| 19 | + |
| 20 | + t.Run("with recipients (COSE_Encrypt, tag 96)", func(t *testing.T) { |
| 21 | + enc := &Envelope{ |
| 22 | + Headers: Headers{ |
| 23 | + Protected: Header{}. |
| 24 | + Set(HeaderLabelType, exampleType). |
| 25 | + Set(HeaderLabelAlg, int64(-65793)), |
| 26 | + Unprotected: Header{}.Set(HeaderLabelIV, []byte("0123456789ab")), |
| 27 | + }, |
| 28 | + Recipients: []*Recipient{{ |
| 29 | + Headers: Headers{ |
| 30 | + Protected: Header{}.Set(HeaderLabelAlg, AlgA256KW), |
| 31 | + Unprotected: Header{}.Set(HeaderLabelKID, []byte("kid-1")), |
| 32 | + }, |
| 33 | + Ciphertext: []byte("wrapped-cek-0123456789abcdef"), |
| 34 | + }}, |
| 35 | + } |
| 36 | + header, err := enc.Encode() |
| 37 | + require.NoError(t, err) |
| 38 | + blob := append(append([]byte{}, header...), ciphertext...) |
| 39 | + |
| 40 | + env, rest, err := DecodeReader(bytes.NewReader(blob)) |
| 41 | + require.NoError(t, err) |
| 42 | + require.Len(t, env.Recipients, 1, "recipient presence marks the tag-96 form") |
| 43 | + gotRest, err := io.ReadAll(rest) |
| 44 | + require.NoError(t, err) |
| 45 | + require.Equal(t, ciphertext, gotRest) |
| 46 | + |
| 47 | + // The streaming decode agrees with the byte-based Decode on both the |
| 48 | + // trailing ciphertext and the AAD (context "Encrypt"). |
| 49 | + byteEnv, byteRest, err := Decode(blob) |
| 50 | + require.NoError(t, err) |
| 51 | + require.Equal(t, ciphertext, byteRest) |
| 52 | + want, err := byteEnv.EncStructure(nil) |
| 53 | + require.NoError(t, err) |
| 54 | + got, err := env.EncStructure(nil) |
| 55 | + require.NoError(t, err) |
| 56 | + require.Equal(t, want, got) |
| 57 | + }) |
| 58 | + |
| 59 | + t.Run("recipient-less (COSE_Encrypt0, tag 16)", func(t *testing.T) { |
| 60 | + enc0 := &Envelope{ |
| 61 | + Headers: Headers{ |
| 62 | + Protected: Header{}. |
| 63 | + Set(HeaderLabelType, exampleType). |
| 64 | + Set(HeaderLabelAlg, int64(-65793)), |
| 65 | + Unprotected: Header{}.Set(HeaderLabelIV, []byte("0123456789ab")), |
| 66 | + }, |
| 67 | + } |
| 68 | + header, err := enc0.Encode() |
| 69 | + require.NoError(t, err) |
| 70 | + blob := append(append([]byte{}, header...), ciphertext...) |
| 71 | + |
| 72 | + env, rest, err := DecodeReader(bytes.NewReader(blob)) |
| 73 | + require.NoError(t, err) |
| 74 | + require.Empty(t, env.Recipients, "recipient absence marks the tag-16 form") |
| 75 | + gotRest, err := io.ReadAll(rest) |
| 76 | + require.NoError(t, err) |
| 77 | + require.Equal(t, ciphertext, gotRest) |
| 78 | + |
| 79 | + // Agrees with the byte-based Decode (context "Encrypt0"). |
| 80 | + byteEnv, byteRest, err := Decode(blob) |
| 81 | + require.NoError(t, err) |
| 82 | + require.Equal(t, ciphertext, byteRest) |
| 83 | + want, err := byteEnv.EncStructure(nil) |
| 84 | + require.NoError(t, err) |
| 85 | + got, err := env.EncStructure(nil) |
| 86 | + require.NoError(t, err) |
| 87 | + require.Equal(t, want, got) |
| 88 | + }) |
| 89 | + |
| 90 | + t.Run("ciphertext split across the decoder buffer and the reader", func(t *testing.T) { |
| 91 | + enc0 := &Envelope{ |
| 92 | + Headers: Headers{Protected: Header{}.Set(HeaderLabelType, exampleType)}, |
| 93 | + } |
| 94 | + header, err := enc0.Encode() |
| 95 | + require.NoError(t, err) |
| 96 | + blob := append(append([]byte{}, header...), ciphertext...) |
| 97 | + |
| 98 | + // One byte at a time forces the header to be reassembled from many reads |
| 99 | + // and the ciphertext to straddle the decoder's read-ahead and the source. |
| 100 | + env, rest, err := DecodeReader(iotest.OneByteReader(bytes.NewReader(blob))) |
| 101 | + require.NoError(t, err) |
| 102 | + require.Empty(t, env.Recipients) |
| 103 | + gotRest, err := io.ReadAll(rest) |
| 104 | + require.NoError(t, err) |
| 105 | + require.Equal(t, ciphertext, gotRest) |
| 106 | + }) |
| 107 | + |
| 108 | + t.Run("expected type mismatch", func(t *testing.T) { |
| 109 | + enc0 := &Envelope{ |
| 110 | + Headers: Headers{Protected: Header{}.Set(HeaderLabelType, "application/other")}, |
| 111 | + } |
| 112 | + header, err := enc0.Encode() |
| 113 | + require.NoError(t, err) |
| 114 | + |
| 115 | + env, rest, err := DecodeReader(bytes.NewReader(header), WithExpectedType(exampleType)) |
| 116 | + require.Nil(t, env) |
| 117 | + require.Nil(t, rest) |
| 118 | + require.ErrorIs(t, err, ErrUnexpectedType) |
| 119 | + }) |
| 120 | + |
| 121 | + t.Run("not a COSE tag", func(t *testing.T) { |
| 122 | + env, rest, err := DecodeReader(bytes.NewReader([]byte{0x01})) |
| 123 | + require.Nil(t, env) |
| 124 | + require.Nil(t, rest) |
| 125 | + require.ErrorIs(t, err, ErrNotEncrypt) |
| 126 | + }) |
| 127 | + |
| 128 | + t.Run("empty input", func(t *testing.T) { |
| 129 | + env, rest, err := DecodeReader(bytes.NewReader(nil)) |
| 130 | + require.Nil(t, env) |
| 131 | + require.Nil(t, rest) |
| 132 | + require.ErrorIs(t, err, ErrMalformed) |
| 133 | + }) |
| 134 | +} |
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