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fix: Recompute Content-Digest header value when signing content-digest component #116

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Merged
dadrus merged 2 commits into from
May 15, 2026
Merged

fix: Recompute Content-Digest header value when signing content-digest component #116

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4be1e3a
fix: Always recompute Content-Digest when signing messages with conte…
dadrus May 15, 2026
ea69904
new tests
dadrus May 15, 2026
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5 changes: 0 additions & 5 deletions message_digester.go
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Original file line number Diff line number Diff line change
Expand Up @@ -20,11 +20,6 @@ type contentDigester struct {
}

func (c contentDigester) update(msg *Message) error {
if val := msg.Header.Get(headerContentDigest); len(val) != 0 {
// header already present. skipping
return nil
}

body, err := c.readBody(msg.Body)
if err != nil {
return err
Expand Down
56 changes: 56 additions & 0 deletions message_digester_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -258,6 +258,62 @@ func TestContentDigesterUpdate(t *testing.T) {
})
},
},
{
uc: "replaces existing content-digest values",
alg: Sha256,
msg: func() *Message {
req, err := http.NewRequestWithContext(
context.TODO(),
http.MethodPost,
"http://example.com/foo",
strings.NewReader(`{"hello": "world"}`),
)
require.NoError(t, err)

req.Header.Add("Content-Digest", "sha-256=:stale-sha256:")
req.Header.Add("Content-Digest", "sha-512=:stale-sha512:")

return MessageFromRequest(req)
}(),
assert: func(t *testing.T, err error, msg *Message) {
t.Helper()

require.NoError(t, err)

require.Equal(t, []string{
"sha-256=:X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=:",
}, msg.Header.Values("Content-Digest"))
},
},
{
uc: "replaces existing content-digest values without specified algorithm",
msg: func() *Message {
req, err := http.NewRequestWithContext(
context.TODO(),
http.MethodPost,
"http://example.com/foo",
strings.NewReader(`{"hello": "world"}`),
)
require.NoError(t, err)

req.Header.Set("Content-Digest", "sha-256=:stale:")

return MessageFromRequest(req)
}(),
assert: func(t *testing.T, err error, msg *Message) {
t.Helper()

require.NoError(t, err)

values := strings.Split(msg.Header.Get("Content-Digest"), ", ")
assert.ElementsMatch(t, values, []string{
"sha-256=:X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=:",
"sha-512=:WZDPaVn/7XgHaAy8pmojAkGWoRx2UFChF41A2svX+TaPm+AbwAgBWnrIiYllu7BNNyealdVLvRwEmTHWXvJwew==:",
})

assert.NotContains(t, msg.Header.Get("Content-Digest"), "stale")
},
},
} {
t.Run(tc.uc, func(t *testing.T) {
cd := &contentDigester{alg: supportedAlgs[tc.alg], algName: tc.alg}
Expand Down
87 changes: 87 additions & 0 deletions signer_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -457,6 +457,7 @@ func TestSignerSign(t *testing.T) {
WithTTL(0),
WithComponents("@authority", "content-digest", "@query-param;name=\"Pet\""),
WithTag("header-example"),
WithContentDigestAlgorithm(Sha512),
},
msg: &Message{
Method: http.MethodPost,
Expand Down Expand Up @@ -498,6 +499,7 @@ func TestSignerSign(t *testing.T) {
WithComponents(
"date", "@method", "@path", "@query", "@authority", "content-type", "content-digest", "content-length",
),
WithContentDigestAlgorithm(Sha512),
},
msg: &Message{
Method: http.MethodPost,
Expand Down Expand Up @@ -537,6 +539,7 @@ func TestSignerSign(t *testing.T) {
WithLabel("sig-b24"),
WithTTL(0),
WithComponents("@status", "content-type", "content-digest", "content-length"),
WithContentDigestAlgorithm(Sha512),
},
msg: &Message{
Method: http.MethodPost,
Expand Down Expand Up @@ -635,6 +638,90 @@ func TestSignerSign(t *testing.T) {
assert.Equal(t, "sig-b26=:wqcAqbmYJ2ji2glfAMaRy4gruYYnx2nEFN2HN6jrnDnQCK1u02Gb04v9EDgwUPiu4A0w6vuQv5lIp5WPpBKRCw==:", sig)
},
},
{
uc: "overwrites stale content-digest when signing content-digest component",
key: Key{KeyID: "test-key-rsa-pss", Algorithm: RsaPssSha512, Key: tkRSAPSS},
opts: []SignerOption{
WithNonce(NonceGetterFunc(func(_ context.Context) (string, error) { return "", nil })),
WithLabel("sig-content-digest"),
WithTTL(0),
WithComponents("content-digest"),
WithContentDigestAlgorithm(Sha256),
},
msg: &Message{
Method: http.MethodPost,
Authority: "example.com",
URL: testURL,
Header: http.Header{
"Host": []string{"example.com"},
"Date": []string{"Tue, 20 Apr 2021 02:07:55 GMT"},
"Content-Type": []string{"application/json"},
"Content-Digest": []string{"sha-256=:stale:"},
"Content-Length": []string{"18"},
},
IsRequest: true,
Body: func() (io.ReadCloser, error) {
return io.NopCloser(strings.NewReader(`{"hello": "world"}`)), nil
},
},
assert: func(t *testing.T, err error, header http.Header) {
t.Helper()

require.NoError(t, err)

assert.Equal(
t,
"sha-256=:X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=:",
header.Get("Content-Digest"),
)

sigInput := header.Get("Signature-Input")
assert.Equal(t, `sig-content-digest=("content-digest");created=1618884473;keyid="test-key-rsa-pss"`, sigInput)

sig := header.Get("Signature")
assert.True(t, strings.HasPrefix(sig, "sig-content-digest=:"))
},
},
{
uc: "preserves existing content-digest when content-digest component is not signed",
key: Key{KeyID: "test-key-rsa-pss", Algorithm: RsaPssSha512, Key: tkRSAPSS},
opts: []SignerOption{
WithNonce(NonceGetterFunc(func(_ context.Context) (string, error) { return "", nil })),
WithLabel("sig-no-content-digest"),
WithTTL(0),
WithComponents("date", "@method"),
WithContentDigestAlgorithm(Sha256),
},
msg: &Message{
Method: http.MethodPost,
Authority: "example.com",
URL: testURL,
Header: http.Header{
"Host": []string{"example.com"},
"Date": []string{"Tue, 20 Apr 2021 02:07:55 GMT"},
"Content-Type": []string{"application/json"},
"Content-Digest": []string{"sha-256=:stale:"},
"Content-Length": []string{"18"},
},
IsRequest: true,
Body: func() (io.ReadCloser, error) {
return io.NopCloser(strings.NewReader(`{"hello": "world"}`)), nil
},
},
assert: func(t *testing.T, err error, header http.Header) {
t.Helper()

require.NoError(t, err)

assert.Equal(t, "sha-256=:stale:", header.Get("Content-Digest"))

sigInput := header.Get("Signature-Input")
assert.Equal(t, `sig-no-content-digest=("date" "@method");created=1618884473;keyid="test-key-rsa-pss"`, sigInput)

sig := header.Get("Signature")
assert.True(t, strings.HasPrefix(sig, "sig-no-content-digest=:"))
},
},
} {
t.Run(tc.uc, func(t *testing.T) {
s, err := NewSigner(tc.key, tc.opts...)
Expand Down