Warrants are surrounded by the <warrant> tag. The signature, if present, covers the whole <warrant-content> tag.
Here is an example warrant:
<!DOCTYPE warrant PUBLIC "-//jtrix.org//TEXT jtrix-0.1//EN" "http://www.jtrix.org/dtd/jtrix-0.1.dtd">
<warrant version='1.0'>
<warrant-content serial='0' starts='995375692839' expires='995378032839'>
<service>
<dn>
<ne name='N'>ulf</ne>
</dn>
<public-key type="x509" encoding="base64">
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDMrQErOQlAvCerJMFijgcPzKZ7avx6Ae/uD1RA1RHwxqxoT6E5ivjqXRtGXp48YIGsD+IMLg0T
Q6SRj8zK1v+PbttKJ2rsJl6/NuBiZoMlpnkQhChdHyXzodQfYa9HaJTdabVxm5ZDHKMbmJh91XPr1IqBiz1qOKFfbE7DhdNCYwIDAQAB
</public-key>
</service>
<ap ac-group="internal">
<bind-server>
<url>http://10.119.8.130:4583/service/1/N%3Dulf</url>
<url>http://10.119.8.128:4583/service/1/N%3Dulf</url>
</bind-server>
</ap>
<warrant-data>
<![CDATA[
org.jtrix.project.cluster.comms.AdminRight ]]>
</warrant-data>
</warrant-content>
<content-signature>
<dn>
<ne name='N'>ulf</ne>
</dn>
<sig encoding="base64" algo='SHA1withRSA'>
c669hU1JR5T/CEQYOFMfzbumKVLX1XsxkO+plhoC9jnSIo1M1gaqt0Kw3Al7j6ufMFnAI4lThfxNwSkqbbJAjlQi/Hf5Tdgu5t/Rf27vmx/jJboA
j5yUoAKJvO30HZ4tQUAUonj/ttS4tOOeCUxZ9Azjt3vZYbseappM6XUwJg8=
</sig>
</content-signature>
</warrant>