vco REST API Holder of key Authirization

Hello

I'm trying to access to vco REST API using HoK which was acquired from sso.

I compose Authorization header by following algorithm:

Authorization: SIGN token="...",

               nonce="143210500:asdfsd",

               signature_alg="RSA-SHA256",

               signature="..."

Where :

token              BASE64(GZIP(SAML2)). Under SAML2 I mean all xml value of a HoK
signature          value of <ds:SignatureValue> XML tag in HoK

and send GET requests to following url https://vcoFQDN:8281/vco/api/users

Unfortunately I get error 500:java.lang.AssertionError: Problem decompressing data: java.util.zip.ZipException: Not in GZIP format

What I'm doing wrong?