PSTwitterAPI

0.0.1

private/Get-OAuthParameters.ps1

                                function Get-OAuthParameters {

    [OutputType('System.Management.Automation.PSCustomObject')]

    Param($ApiKey, $ApiSecret, $AccessToken, $AccessTokenSecret, $Method, $ResourceUrl, $Parameters)

    Process{

        Try {

            ## Generate a random 32-byte string. I'm using the current time (in seconds) and appending 5 chars to the end to get to 32 bytes

            ## Base64 allows for an '=' but Twitter does not.  If this is found, replace it with some alphanumeric character

            $OAuthNonce = [System.Convert]::ToBase64String(([System.Text.Encoding]::ASCII.GetBytes("$([System.DateTime]::Now.Ticks.ToString())12345"))).Replace('=', 'g')

            ## Find the total seconds since 1/1/1970 (epoch time)

            $OAuthTimestamp = [System.Convert]::ToInt64((Get-Eposh).TotalSeconds).ToString();

            ## EscapeDataString the parameters

            foreach($Param in $($Parameters.Keys)){

                $Parameters[$Param] = [System.Uri]::EscapeDataString($Parameters[$Param])

            }

            ## Build the enpoint url

            $EndPointUrl = "${ResourceUrl}?"

            $Parameters.GetEnumerator() | Sort-Object Name | ForEach-Object { $EndPointUrl += "$($_.Key)=$($_.Value)&" }

            $EndPointUrl = $EndPointUrl.TrimEnd('&')

            ## Build the signature

            $SignatureBase = "$([System.Uri]::EscapeDataString("${ResourceUrl}"))&"

            $SignatureParams = @{

                'oauth_consumer_key' = $ApiKey;

                'oauth_nonce' = $OAuthNonce;

                'oauth_signature_method' = 'HMAC-SHA1';

                'oauth_timestamp' = $OAuthTimestamp;

                'oauth_token' = $AccessToken;

                'oauth_version' = "1.0";

            }

            $Parameters.Keys | ForEach-Object { $SignatureParams.Add($_ , $Parameters.Item($_)) }

            ## Create a string called $SignatureBase that joins all URL encoded 'Key=Value' elements with a &

            ## Remove the URL encoded & at the end and prepend the necessary 'POST&' verb to the front

            $SignatureParams.GetEnumerator() | Sort-Object Name | ForEach-Object { $SignatureBase += [System.Uri]::EscapeDataString("$($_.Key)=$($_.Value)&") }

            $SignatureBase = $SignatureBase.Substring(0,$SignatureBase.Length-3)

            $SignatureBase = $Method+'&' + $SignatureBase

            ## Create the hashed string from the base signature

            $SignatureKey = [System.Uri]::EscapeDataString($ApiSecret) + "&" + [System.Uri]::EscapeDataString($AccessTokenSecret);

            $hmacsha1 = new-object System.Security.Cryptography.HMACSHA1;

            $hmacsha1.Key = [System.Text.Encoding]::ASCII.GetBytes($SignatureKey);

            $OAuthSignature = [System.Convert]::ToBase64String($hmacsha1.ComputeHash([System.Text.Encoding]::ASCII.GetBytes($SignatureBase)));

            ## Build the authorization headers using most of the signature headers elements.  This is joining all of the 'Key=Value' elements again

            ## and only URL encoding the Values this time while including non-URL encoded double quotes around each value

            $OAuthParameters = $SignatureParams

            $OAuthParameters.Add('oauth_signature', $OAuthSignature)

            $OAuthString = 'OAuth '

            $OAuthParameters.GetEnumerator() | Sort-Object Name | ForEach-Object { $OAuthString += $_.Key + '="' + [System.Uri]::EscapeDataString($_.Value) + '", ' }

            $OAuthString = $OAuthString.TrimEnd(', ')

            Write-Verbose "Using authorization string '$TwitOAuthStringterOauthString'"

            $OAuthParameters.Add('endpoint_url', $EndPointUrl)

            $OAuthParameters.Add('endpoint_method', $Method)

            $OAuthParameters.Add('endpoint_authorization', $OAuthString)

            Return $OAuthParameters

        } Catch {

            Write-Error $_.Exception.Message

        }

    }

}