Coldfusion

<cfset key = '943b421c9eb07c830af81030552c86009268de4e532ba2ee2eab8247c6da0881'>
<cfset salt = '520f986b998545b4785e0defbc4f3c1203f22de2374a3d53cb7a7fe9fea309c5'>

<!--- converting hexa to binary --->
<cfset keyBin = #binaryDecode(key, 'hex')#>

<!--- converting binary to string--->
<cfset keyBin =  #toString(keyBin)#>

<cfif NOT isDefined("keyBin")>
		<cfabort showError = "Key expected to be hex-encoded string">
</cfif>

<!--- converting hexa to binary --->
<cfset saltBin = #binaryDecode(salt, 'hex')#>

<!--- converting binary to string--->
<cfset saltBin =  #toString(saltBin)#>

<!--- <cfdump var="#saltBin#"> --->

<cfif NOT isDefined("saltBin")>
		<cfabort showError = "Salt expected to be hex-encoded string">
</cfif>

<cfset resize 		=  'fill'>
<cfset width 		=  '300'>
<cfset height 		=  '300'>
<cfset gravity 		=  'no'>
<cfset enlarge 		=  1>
<cfset extension 	=  'png'>

<cfset imgurl 		=  'http://img.example.com/pretty/image.jpg'>

<!--- <cfdump var= #ToBase64(imgurl)#> --->

<cfset encoded 		=  ToBase64(imgurl)>

<cfset encoded 		=  replaceNoCase(encoded, "+", "-",'ALL')>
<cfset encoded 		=  replaceNoCase(encoded, "/", "_",'ALL')>

<cfset encoded = trim(encoded)>

<cfif right(encoded, 1) is "=">
    <cfset encoded = left(encoded, len(encoded)-1)>
</cfif>

<!--- <cfdump var= #encoded#> --->

<cfset path = "/rs:"&resize&":"&width&":"&height&":"&enlarge&"/g:"&gravity&"/"&encoded&"."&extension>


<cfset abc = hmac(saltBin&path,keyBin,"HMACSHA256")>
<cfoutput>#abc#</cfoutput>

<!--- <cfoutput>#abc#</cfoutput> --->

<!--- <cfoutput>#abc#</cfoutput> --->
<cfabort>

<!--- <!--- converting hexa to binary --->
<cfset abc = #binaryDecode(abc, 'hex')#>  --->


<!--- converting binary to string--->
<!--- cfset abc = binaryEncode( binaryDecode(abc, "hex"), "base64" )> --->




<!--- <cfoutput>#binaryEncode( binaryDecode(abc, "hex"), "base64" )#</cfoutput> --->




<cfabort>

<!--- <cfset url 			=  'http://img.example.com/pretty/image.jpg'>

$encodedUrl = rtrim(strtr(base64_encode($url), '+/', '-_'), '='); --->