The Open Bank Project OAuth server support "SHA1" and "SHA256" so the parameter MUST be set to “HMAC-SHA1" or “HMAC-SHA256”

The Open Bank Project OAuth 1.0 implementation uses the “HMAC-SHA1” and “HMAC-SHA256” as signing methods. The key to sign the base string is the concatenation of the consumer secret and the token secret with the “&” character in the middle like this: oauth_consumer_secret&oauth_token_secret, in the first step the application does not have yet a token so it will be an empty string.

The signature that results from the signature process MUST be encoded in base 64 also since the protocol requires encoding all the OAuth parameters.

OAUTH_SIG_METHOD_HMACSHA256 (string)

OAuth HMAC-SHA256 署名方式。