Java Security

I'm sending this soap message to the server:

<?xml version='1.0' encoding='utf-8'?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
<soapenv:Header>
<wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" soapenv:mustUnderstand="1">
<ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#" Id="Signature-29784916">
<ds:SignedInfo>
<ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#" />
<ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1" />
<ds:Reference URI="#id-32207230">
<ds:Transforms>
<ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#" />
</ds:Transforms>
<ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1" />
<ds:DigestValue>Iy8TOsjF065HPdu+q99l0CrC/Mo=</ds:DigestValue>
</ds:Reference>
</ds:SignedInfo>
<ds:SignatureValue>I6ruBXc+mTx6cooaOEWIz2rfuCzbftNdq2jH6b9DtJLPnA8l0bUHU4X52QT2OkuyxnAtUkbXX669Mjw/dC3Onl0Q3cubzr99gbpr13PRRmbVxwzG16xAWYwplP0fz1eN3ny6zhY7n3g7rsQZP0v6eI+NYDrIfRC5l6PQsS4ypQg=</ds:SignatureValue>
<ds:KeyInfo Id="KeyId-30076848">
<wsse:SecurityTokenReference xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" wsu:Id="STRId-4070693">
<wsse:KeyIdentifier EncodingType="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-soap-message-security-1.0#Base64Binary" ValueType="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-x509-token-profile-1.0#X509v3">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</wsse:KeyIdentifier>
</wsse:SecurityTokenReference>
</ds:KeyInfo>
</ds:Signature>
<wsu:Timestamp xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" wsu:Id="Timestamp-11474887">
<wsu:Created>2008-05-23T16:15:16.405Z</wsu:Created>
<wsu:Expires>2008-05-23T16:50:38.405Z</wsu:Expires>
</wsu:Timestamp>
</wsse:Security>
</soapenv:Header>
<soapenv:Body xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" wsu:Id="id-32207230" />
</soapenv:Envelope>

How is this digest value computed "Iy8TOsjF065HPdu+q99l0CrC/Mo=" ??

Is this value taken "id-32207230" -> digest("id-32207230") = "Iy8TOsjF065HPdu+q99l0CrC/Mo="

I know that the value is taken through reference URI. How is this value computed in my case?
Please help! Thank you!