Fix bug where TSA signing fails if cert hash != content hash.

This was fixed upstream in
digitorus/timestamp#19.

We should cut a patch release - the buggy behavior was introduced in
v1.1.2.

NOTE: This potentially breaks some users if they are relying on the new
cert hash behavior introduced in v1.1.2 to support other hash types, but
this fixes those who were broken by the v1.1.2 update.
Support for other hash types can be added in another PR by moving to using
[timestamp.CreateResponseWithOpts](https://pkg.go.dev/github.com/digitorus/timestamp#Timestamp.CreateResponseWithOpts)
and passing in the appropriate hash (but I'm considering that out of
scope for this PR).

Signed-off-by: Billy Lynch <billy@chainguard.dev>

go.mod

@@ -6,7 +6,7 @@ require (
 	cloud.google.com/go/security v1.15.1
 	github.com/beevik/ntp v1.3.0
 	github.com/digitorus/pkcs7 v0.0.0-20230818184609-3a137a874352
-	github.com/digitorus/timestamp v0.0.0-20230821155606-d1ad5ca9624c
+	github.com/digitorus/timestamp v0.0.0-20230902153158-687734543647
 	github.com/go-chi/chi v4.1.2+incompatible
 	github.com/go-openapi/errors v0.20.4
 	github.com/go-openapi/loads v0.21.2

go.sum

@@ -134,8 +134,8 @@ github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/digitorus/pkcs7 v0.0.0-20230713084857-e76b763bdc49/go.mod h1:SKVExuS+vpu2l9IoOc0RwqE7NYnb0JlcFHFnEJkVDzc=
 github.com/digitorus/pkcs7 v0.0.0-20230818184609-3a137a874352 h1:ge14PCmCvPjpMQMIAH7uKg0lrtNSOdpYsRXlwk3QbaE=
 github.com/digitorus/pkcs7 v0.0.0-20230818184609-3a137a874352/go.mod h1:SKVExuS+vpu2l9IoOc0RwqE7NYnb0JlcFHFnEJkVDzc=
-github.com/digitorus/timestamp v0.0.0-20230821155606-d1ad5ca9624c h1:kgG83Hfj3YXkUbrihwBxDc0COzP1ZejiDSr4/fItT0E=
-github.com/digitorus/timestamp v0.0.0-20230821155606-d1ad5ca9624c/go.mod h1:GvWntX9qiTlOud0WkQ6ewFm0LPy5JUR1Xo0Ngbd1w6Y=
+github.com/digitorus/timestamp v0.0.0-20230902153158-687734543647 h1:WOk5Aclr/+sZ2/SX2YyxulNFwZOUhSrDJLw5KbHKmdE=
+github.com/digitorus/timestamp v0.0.0-20230902153158-687734543647/go.mod h1:GvWntX9qiTlOud0WkQ6ewFm0LPy5JUR1Xo0Ngbd1w6Y=
 github.com/dnaeon/go-vcr v1.2.0 h1:zHCHvJYTMh1N7xnV7zf1m1GPBF9Ad0Jk/whtQ1663qI=
 github.com/docker/go-units v0.5.0 h1:69rxXcBk27SvSaaxTtLh/8llcHD8vYHT7WSdRZ/jvr4=
 github.com/docker/go-units v0.5.0/go.mod h1:fgPhTUdO+D/Jk86RDLlptpiXQzgHJF7gydDDbaIK4Dk=

pkg/api/timestamp.go

@@ -173,7 +173,7 @@ func TimestampResponseHandler(params ts.GetTimestampResponseParams) middleware.R
 		ExtraExtensions:   req.Extensions,
 	}
 
-	resp, err := tsStruct.CreateResponse(api.certChain[0], api.tsaSigner)
+	resp, err := tsStruct.CreateResponseWithOpts(api.certChain[0], api.tsaSigner, crypto.SHA256)
 	if err != nil {
 		return handleTimestampAPIError(params, http.StatusInternalServerError, err, failedToGenerateTimestampResponse)
 	}

pkg/client/mock/mock_tsa_client.go

@@ -137,7 +137,7 @@ func (c *TSAClient) GetTimestampResponse(params *ts.GetTimestampResponseParams,
 		tsStruct.Time = c.Time
 	}
 
-	resp, err := tsStruct.CreateResponse(c.CertChain[0], c.Signer)
+	resp, err := tsStruct.CreateResponseWithOpts(c.CertChain[0], c.Signer, crypto.SHA256)
 	if err != nil {
 		return nil, err
 	}

pkg/verification/verify_test.go

@@ -510,7 +510,7 @@ func createSignedTimestamp(certChain []*x509.Certificate, sv *signature.ECDSASig
 		ExtraExtensions:   req.Extensions,
 	}
 
-	resp, err := tsTemplate.CreateResponse(certChain[0], sv)
+	resp, err := tsTemplate.CreateResponseWithOpts(certChain[0], sv, crypto.SHA256)
 	if err != nil {
 		return nil, fmt.Errorf("unexpectedly failed to create timestamp response: %v", err)
 	}