Tom,
You need to download the Verisign CA certs to include in your projects. Here's the CA file here that I used to get mine working.
I also have a blog post about how to use secure S3 URLs:
http://www.valtira.com/page/1/valtira-b ... ign-s3.jsp-----BEGIN CERTIFICATE-----
MIIE+DCCA+CgAwIBAgIQeo+SIwIaV15+swESSrlhUDANBgkqhkiG9w0BAQUFADCB
tTELMAkGA1UEBhMCVVMxFzAVBgNVBAoTDlZlcmlTaWduLCBJbmMuMR8wHQYDVQQL
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W4wWQZ5AWPUZmZ4Dl8XgUPtCeArv8R+9zQVMHQ==
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
MIIDAjCCAmsCEH3Z/gfPqB63EHln+6eJNMYwDQYJKoZIhvcNAQEFBQAwgcExCzAJ
BgNVBAYTAlVTMRcwFQYDVQQKEw5WZXJpU2lnbiwgSW5jLjE8MDoGA1UECxMzQ2xh
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oJ2daZH9
-----END CERTIFICATE-----