Assembling the XML Signature

<< Creating a Public Key Pair | Printing the Resulting Document >>

GENENVELOPED

XAMPLE

229

· A single

Transform

, the enveloped

Transform

, which is required for

enveloped signatures so that the signature itself is removed before calcu-
lating the signature value

Reference ref = fac.newReference

("", fac.newDigestMethod(DigestMethod.SHA1, null),

Collections.singletonList

(fac.newTransform(Transform.ENVELOPED,

(TransformParameterSpec) null)), null, null);

Next, we create the

SignedInfo

object, which is the object that is actually

signed, as shown below. When creating the

SignedInfo

, we pass as parameters:

· The

CanonicalizationMethod

(we use inclusive and preserve comments)

· The

SignatureMethod

(we use DSA)

· A list of

References

(in this case, only one)

SignedInfo si = fac.newSignedInfo

(fac.newCanonicalizationMethod

(CanonicalizationMethod.INCLUSIVE_WITH_COMMENTS,

(C14NMethodParameterSpec) null),

fac.newSignatureMethod(SignatureMethod.DSA_SHA1, null),
Collections.singletonList(ref));

Next, we create the optional

KeyInfo

object, which contains information that

enables the recipient to find the key needed to validate the signature. In this
example, we add a

KeyValue

object containing the public key. To create

KeyInfo

and its various subtypes, we use a

KeyInfoFactory

object, which can be

obtained by invoking the

getKeyInfoFactory

method of the

XMLSignature-

Factory

, as follows:

KeyInfoFactory kif = fac.getKeyInfoFactory();

We then use the

KeyInfoFactory

to create the

KeyValue

object and add it to a

KeyInfo

object:

KeyValue kv = kif.newKeyValue(kp.getPublic());
KeyInfo ki = kif.newKeyInfo(Collections.singletonList(kv));

Finally, we create the

XMLSignature

object, passing as parameters the

Signed-

Info

and

KeyInfo

objects that we created earlier:

XMLSignature signature = fac.newXMLSignature(si, ki);