src/Signer.php
private function addDigest($message)
    {
        if (!array_search('digest', $this->headerList->names)) {
            $this->headerList->names[] = 'digest';
        }
        $message = $message->withoutHeader('Digest')
            ->withHeader(
                'Digest',
                'SHA-256='.base64_encode(hash('sha256', $message->getBody(), true))
            );

        return $message;
    }
private function addDigest($message)
    {
        if (!array_search('digest', $this->headerList->names)) {
            $this->headerList->names[] = 'digest';
        }
        $message = $message->withoutHeader('Digest')
            ->withHeader(
                'Digest',
                'SHA-256='.base64_encode(hash('sha256', $message->getBody(), true))
            );

        return $message;
    }
@param RequestInterface $message

@return RequestInterface