Token invalid - Invalid AuthSub token

[daninmanchester]

I'm using oauth but when I post a request I get Token invalid -
Invalid AuthSub token.

I'm using the following authorization header :

OAuth oauth_consumer_key=www.myconsumerkey.co.uk, oauth_nonce=2953862,
oauth_signature_method=HMAC-SHA1, oauth_timestamp=1253554167,
oauth_token=4/bKNFDWNz-xUMBMRbh5xy_BYjq6_B, oauth_version=1.0,
oauth_signature=Wqdg%2BNmvf5twTBRK18OqenVDyQw%3D

With ContentType = "application/atom+xml

posting to
http://www.blogger.com/feeds/blog id here/posts/default

with an atom item in the post data.

What's going wrong?

[daninmanchester]

I've just spotted something.

my key is :
4/6RVYg_UmxCdPlPs79b0OYTRTMVKS

I encode this as (spaces added for clarity) :
4 %2F 6RVYg_UmxCdPlPs79b0OYTRTMVKS

but google is saying the base string should be :
4 %252F 6RVYg_UmxCdPlPs79b0OYTRTMVKS

/ is supposed to be 2F where is google getting the %252F from?