My XML digital signature has the following excerpts:
<Signature Id="idPackageSignature" xmlns="http://www.w3.org/2000/09/xmldsig#">
<SignedInfo>
<CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
<SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
<Reference URI="#idOfficeObject" Type="http://www.w3.org/2000/09/xmldsig#Object">
<DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
<DigestValue>ofqf9+Tj0qTkkExCEOwFz0V4aNo=</DigestValue>
</Reference>
</SignedInfo>
<Object Id="idOfficeObject"><SignatureProperties><SignatureProperty Id="idOfficeV1Details" Target="#idPackageSignature"><SignatureInfoV1 xmlns="http://schemas.microsoft.com/office/2006/digsig"><SetupID/><SignatureText/><SignatureImage/><SignatureComments>test</SignatureComments><WindowsVersion>6.1</WindowsVersion><OfficeVersion>14.0</OfficeVersion><ApplicationVersion>14.0</ApplicationVersion><Monitors>1</Monitors><HorizontalResolution>1920</HorizontalResolution><VerticalResolution>1200</VerticalResolution><ColorDepth>32</ColorDepth><SignatureProviderId>{00000000-0000-0000-0000-000000000000}</SignatureProviderId><SignatureProviderUrl/><SignatureProviderDetails>9</SignatureProviderDetails><ManifestHashAlgorithm>http://www.w3.org/2000/09/xmldsig#sha1</ManifestHashAlgorithm><SignatureType>1</SignatureType></SignatureInfoV1></SignatureProperty></SignatureProperties></Object>
The referenced Object element is supposed to have the digest value ofqf9+Tj0qTkkExCEOwFz0V4aNo=. I canonicalize the Object element, and get the following output, which seems correct to me:
<Object Id="idOfficeObject"><SignatureProperties><SignatureProperty Id="idOfficeV1Details" Target="#idPackageSignature"><SignatureInfoV1 xmlns="http://schemas.microsoft.com/office/2006/digsig"><SetupID></SetupID><SignatureText></SignatureText><SignatureImage></SignatureImage><SignatureComments>test</SignatureComments><WindowsVersion>6.1</WindowsVersion><OfficeVersion>14.0</OfficeVersion><ApplicationVersion>14.0</ApplicationVersion><Monitors>1</Monitors><HorizontalResolution>1920</HorizontalResolution><VerticalResolution>1200</VerticalResolution><ColorDepth>32</ColorDepth><SignatureProviderId>{00000000-0000-0000-0000-000000000000}</SignatureProviderId><SignatureProviderUrl></SignatureProviderUrl><SignatureProviderDetails>9</SignatureProviderDetails><ManifestHashAlgorithm>http://www.w3.org/2000/09/xmldsig#sha1</ManifestHashAlgorithm><SignatureType>1</SignatureType></SignatureInfoV1></SignatureProperty></SignatureProperties></Object>
I store it in a file 'inputxml', and try to get the base64 encoded version of the sha1 digest using the following command:
% shasum inputxml | cut -f 1 -d ' ' | xxd -r -p | base64
/zTi8HGHX9X+csjULYLt6FLrm3g=
The computed digest value does not match what is in the XML signature. What am I doing wrong? I have tried multiple various methods and tweaks, but cannot get the correct digest value.
Note: The XML Signature verifies correctly. So the value is correct, but I am missing some step or detail. Thanks for your help. Please let me know how can I elaborate or clarify my question further if it is not very clear.
Finally I got it to work. There were two issues with my canonicalized markup:
a] The namespace string was incorrectly placed. It had to be <Object xmlns="http://www.w3.org/2000/09/xmldsig#" Id="idOfficeObject">
b] There was an errant newline at the end of the file, since I was modifying these files in a text editor.
Fixing these issues, and running shasum on it gave me the correct output. Thanks for your help, folks.