Help porting HMAC-SHA256 code

[jondecker76]

I’m trying to port some fairly simple code to make my own HMAC-SHA256 function, but I’m not getting expected results (I’m sure it’s a string vs byte issue).  Here is information on the algorithm:

https://datatracker.ietf.org/doc/html/rfc2104

https://en.wikipedia.org/wiki/HMAC

 

Here is where my tests are so far…

Monkey

#Import"<std>" Using std..</p> <p>Function HMAC256:String(key:String, message:String) Local blocksize:=64 Local opad:UByte[]= New UByte[blocksize]' $5c Where blocksize is that of the underlying hash Function Local ipad:UByte[] = New UByte[blocksize]' $36</p> <p> ' zero out the inner and outer pads For Local i:=0 To blocksize-1 opad[i]=$00 ipad[i]=$00 Next</p> <p> ' Reset the key to blocksize length If (key.Length > blocksize) Then key = SHA256(key) 'Where 'hash' is the underlying hash function End If</p> <p> ' Copy the keys to the pads. We need the actual byte values For Local i:=0 To key.Length-1 opad[i]=UByte(key[i]) ipad[i]=UByte(key[i]) Next</p> <p> For Local i:=0 To key.Length - 1 Step 1 ipad[i] = ipad[i] ~ $36 opad[i] = opad[i] ~ $5c end for</p> <p> Local opadStr:String Local ipadStr:String</p> <p> For Local this:=Eachin opad opadStr+=this Next For Local this:=Eachin ipad ipadStr+=this Next</p> <p> Return SHA256(opadStr + SHA256(ipadStr + message)) ' Where || is concatenation end function</p> <p>Function Main() Local key:="Jefe" Local data:= "what do ya want for nothing?" Local test:="750c783e6ab0b503eaa86e310a5db738"</p> <p> Local digest:=HMAC256(key,data)</p> <p> If digest=test Print "The expected digest was returned!" Else Print "The digest " + digest + " is incorrect!" Endif End

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#Import"<std>" Using std..     Function HMAC256:String(key:String, message:String) Local blocksize:=64     Local opad:UByte[]= New UByte[blocksize]' $5c Where blocksize is that of the underlying hash Function     Local ipad:UByte[] = New UByte[blocksize]' $36     ' zero out the inner and outer pads For Local i:=0 To blocksize-1 opad[i]=$00 ipad[i]=$00 Next   ' Reset the key to blocksize length     If (key.Length > blocksize) Then         key = SHA256(key) 'Where 'hash' is the underlying hash function     End If          ' Copy the keys to the pads.  We need the actual byte values     For Local i:=0 To key.Length-1     opad[i]=UByte(key[i])     ipad[i]=UByte(key[i]) Next       For Local i:=0 To key.Length - 1 Step 1         ipad[i] = ipad[i] ~ $36         opad[i] = opad[i] ~ $5c     end for Local opadStr:String Local ipadStr:String For Local this:=Eachin opad opadStr+=this Next For Local this:=Eachin ipad ipadStr+=this Next       Return SHA256(opadStr + SHA256(ipadStr + message)) ' Where || is concatenation end function     Function Main() Local key:="Jefe" Local data:= "what do ya want for nothing?" Local test:="750c783e6ab0b503eaa86e310a5db738" Local  digest:=HMAC256(key,data) If digest=test Print "The expected digest was returned!" Else Print "The digest " + digest + " is incorrect!" Endif End

 

Any pointers?

 

Thanks

[jondecker76]

Still working on this.  I’m much happier with the state of the code, but it still isn’t returning expected results :/

 

Monkey

Function HMAC256:String(key:String,message:String) Local B:=64 ' Blocksize (bytes) Local K:=New DataBuffer(B) ' Key Local ipad:=New DataBuffer(B) ' Inner pad string Local opad:=New DataBuffer(B) ' Outer pad string</p> <p> ' Lets handle our key first! ' Truncate the key if over bloccksize If key.Length>B Then key=SHA256(key) K.PokeString(0,key)</p> <p> ' Lets fill ipad and opad For Local i:=0 To B-1 ipad.PokeUByte(i,$36~K.PeekUByte(i)) opad.PokeUByte(i,$5c~K.PeekUByte(i)) Next</p> <p> Return SHA256(opad.PeekString(0) + SHA256(ipad.PeekString(0)+ message)) End

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Function HMAC256:String(key:String,message:String) Local B:=64 ' Blocksize (bytes) Local K:=New DataBuffer(B) ' Key Local ipad:=New DataBuffer(B) ' Inner pad string Local opad:=New DataBuffer(B) ' Outer pad string   ' Lets handle our key first! ' Truncate the key if over bloccksize If key.Length>B Then key=SHA256(key) K.PokeString(0,key)   ' Lets fill ipad and opad For Local i:=0 To B-1 ipad.PokeUByte(i,$36~K.PeekUByte(i)) opad.PokeUByte(i,$5c~K.PeekUByte(i)) Next   Return SHA256(opad.PeekString(0) + SHA256(ipad.PeekString(0)+ message)) End

[jondecker76]

Here is a full project to show the issue.  Everything looks right, but I can’t figure out why it’s not returning expected results

Monkey

#Import"<std>" #Import"<libc>"</p> <p>Using std.. Using libc..</p> <p>' Simple HMAC-SHA256 function ' See: ' https://en.wikipedia.org/wiki/HMAC ' https://datatracker.ietf.org/doc/html/rfc2104 ' https://www.freeformatter.com/hmac-generator.html</p> <p>Function HMAC256:String(key:String,message:String) Local B:=64 ' Blocksize (bytes) Local K:=New DataBuffer(B) ' Key Local ipad:=New DataBuffer(B) ' Inner pad Local opad:=New DataBuffer(B) ' Outer pad</p> <p> ' Lets handle our key first! ' Truncate the key if over blocksize, If key.Length>B Then key=SHA256(key) Zero(K.Data,B) K.PokeString(0,key) Display(K.Data,B,"KEY BYTES")</p> <p> ' Lets fill ipad and opad For Local i:=0 To B-1 ipad.PokeUByte(i,$36~K.PeekUByte(i)) opad.PokeUByte(i,$5c~K.PeekUByte(i)) Next Display(ipad.Data,B,"IPAD BYTES AFTER XOR") Display(opad.Data,B,"OPAD BYTES AFTER XOR")</p> <p> Return SHA256(opad.PeekString(0) + SHA256(ipad.PeekString(0)+message)) End</p> <p>Function Zero(db:UByte Ptr,len:Int) For Local i:=0 To len-1 db[i]=$0 Next End</p> <p>Function LPad:String(str:String,len:Int,char:String) While str.Length < len str=char+str End Return str End</p> <p>Function Display(arr:UByte Ptr,len:Int,title:String="") Local lineHex:String Local lineAscii:String Local retVal:String Local j:=0</p> <p> If title<>"" Print title Print "===========================================================" End For Local i:=0 To len-1 lineHex+=LPad(Hex(arr[i]),2,"0") + " " lineAscii+=String.FromChar(arr[i]) + " " If (i Mod 8)+1=8 lineHex += "| " Endif</p> <p> If (i Mod 16)+1=16 Print LPad(Hex(j),4,"0") + ": "+ lineHex + lineAscii 'retVal+=lineHex + "|| "+lineAscii+"~n" lineAscii="" lineHex="" j+=16 Endif Next If lineHex<>"" Then Print LPad(Hex(j),4,"0") + ": "+lineHex + lineAscii Print "~n" End Function</p> <p>Function Main() Local key:="jondecker76" Local data:= "hello" Local expectedResult:="ab9ce9ef1575259bdb2beb438d8501479b5a63298bc33e4f4fdee87760fd3b75"</p> <p> Local result:=HMAC256(key,data)</p> <p> If result=expectedResult Print "The expected result was returned!" Else Print "~nThe result " + result + " is incorrect!" Endif End

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#Import"<std>" #Import"<libc>"   Using std.. Using libc..   ' Simple HMAC-SHA256 function ' See: ' https://en.wikipedia.org/wiki/HMAC ' https://datatracker.ietf.org/doc/html/rfc2104 ' https://www.freeformatter.com/hmac-generator.html   Function HMAC256:String(key:String,message:String) Local B:=64 ' Blocksize (bytes) Local K:=New DataBuffer(B) ' Key Local ipad:=New DataBuffer(B) ' Inner pad Local opad:=New DataBuffer(B) ' Outer pad   ' Lets handle our key first! ' Truncate the key if over blocksize, If key.Length>B Then key=SHA256(key) Zero(K.Data,B) K.PokeString(0,key) Display(K.Data,B,"KEY BYTES") ' Lets fill ipad and opad For Local i:=0 To B-1 ipad.PokeUByte(i,$36~K.PeekUByte(i)) opad.PokeUByte(i,$5c~K.PeekUByte(i)) Next Display(ipad.Data,B,"IPAD BYTES AFTER XOR") Display(opad.Data,B,"OPAD BYTES AFTER XOR") Return SHA256(opad.PeekString(0) + SHA256(ipad.PeekString(0)+message)) End   Function Zero(db:UByte Ptr,len:Int) For Local i:=0 To len-1 db[i]=$0 Next End   Function LPad:String(str:String,len:Int,char:String) While str.Length < len str=char+str End Return str End   Function Display(arr:UByte Ptr,len:Int,title:String="") Local lineHex:String Local lineAscii:String Local retVal:String Local j:=0 If title<>"" Print title Print "===========================================================" End For Local i:=0 To len-1 lineHex+=LPad(Hex(arr[i]),2,"0") + " " lineAscii+=String.FromChar(arr[i]) + " " If (i Mod 8)+1=8 lineHex += "| " Endif If (i Mod 16)+1=16 Print LPad(Hex(j),4,"0") + ": "+ lineHex + lineAscii 'retVal+=lineHex + "|| "+lineAscii+"~n" lineAscii="" lineHex="" j+=16 Endif Next If lineHex<>"" Then Print LPad(Hex(j),4,"0") + ": "+lineHex + lineAscii Print "~n" End Function     Function Main() Local key:="jondecker76" Local data:= "hello" Local expectedResult:="ab9ce9ef1575259bdb2beb438d8501479b5a63298bc33e4f4fdee87760fd3b75" Local result:=HMAC256(key,data) If result=expectedResult Print "The expected result was returned!" Else Print "~nThe result " + result + " is incorrect!" Endif End

[abakobo]

I ported part of a library to get this done. Code is from https://create.stephan-brumme.com/hash-library/ . Please check for the license(MIT I think).

I had to remove the call to endian.h because it’s a mess with OSX. This result in this port working on “Little Endian” OS/Hardware ONLY (which is all common now but I preffer to tell). (Networks seems to be “Big Endian” though!)
Sorry not to review your code but for me it’s easyer to Import C++ code..

I’m using a libc.char_t array to get my CString to avoid memory leaks.
Hope it works well for you.

Code in attached zip.

PS: I’ve seen on StackOverflow that the most common problem with hashes is a confusion with chars and bytes.
PS2: you could check the code in std.digest to see how the types are managed in there if you want to continue your mx2 education..

Attachments:

1. hmac256_64.zip

[jondecker76]

Thank you very much, this is very helpful.

I’ll definitely still work on figuring out what is causing it to fail  in pure Mx2, but at least it won’t hold me up on my project!

[jondecker76]

Ouch, this keeps getting stranger.

It’s easy to see the first obvious problem with this test..  MX2 text can’t represent characters $80-$FF?  Strange!  The strangest thing is that $FF isn’t even possible, and equates to $00?  Run the test below and look at the last entry.  Yes, I see that the first byte is $FF for >$80…  But that stops at $FFFE.  Where is $FFFF?   Is this expected behavior or a bug?

 

Monkey

#Import "<std>"</p> <p>Using std.. </p> <p>Function Main() Local db:DataBuffer=New DataBuffer(255)</p> <p> For Local i:=0 To 255 db.PokeUByte(i,i) Next</p> <p> Local test:=db.PeekString(0) For Local i:= 0 To 255 Print test[i] + " : " + Hex(test[i]) Next End

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#Import "<std>"   Using std..     Function Main() Local db:DataBuffer=New DataBuffer(255) For Local i:=0 To 255 db.PokeUByte(i,i) Next Local test:=db.PeekString(0) For Local i:= 0 To 255 Print test[i] + " : " + Hex(test[i]) Next End

[Danilo]

0 To 255 requires a DataBuffer of 256 bytes.

[Danilo]

Strings in Monkey2 are 16-bit Unicode Strings.

 

Please try the following code to catch ASCII strings from DataBuffer and convert it to Unicode-Monkey2-Strings.

Monkey

#Import "<std>"</p> <p>Using std.. </p> <p>Function Main() Local db:DataBuffer=New DataBuffer(256)</p> <p> For Local i:=0 To 255 db.PokeUByte(i,i) Next</p> <p> Local test:=db.PeekString(0, StringFormat.ASCII) For Local i:= 0 To 255 Print test[i] + " : " + Hex(test[i]) Next End</p> <p>Enum StringFormat ASCII ' UTF8 ' UTF16 End</p> <p>Class DataBuffer Extension</p> <p> Method PeekString:String( offset:Int, type:StringFormat )</p> <p> Local ret:String = ""</p> <p> Select type Case StringFormat.ASCII Local len:Int = Self.Length - offset If len < 1 Then Return ""</p> <p> For Local i:Int = 0 Until len ret += String.FromChar( Self.PeekUByte(offset+i) ) Next End Select</p> <p> Return ret End</p> <p> Method PeekString:String( offset:Int, count:Int, type:StringFormat )</p> <p> Local ret:String = "" Local len :Int</p> <p> Select type Case StringFormat.ASCII len = Self.Length - offset len = Min(len,count) If len < 1 Then Return ""</p> <p> For Local i:Int = 0 Until len ret += String.FromChar( Self.PeekUByte(offset+i) ) Next End Select</p> <p> Return ret End</p> <p>End

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#Import "<std>" Using std..   Function Main() Local db:DataBuffer=New DataBuffer(256) For Local i:=0 To 255 db.PokeUByte(i,i) Next Local test:=db.PeekString(0, StringFormat.ASCII) For Local i:= 0 To 255 Print test[i] + " : " + Hex(test[i]) Next End   Enum StringFormat     ASCII     ' UTF8     ' UTF16 End   Class DataBuffer Extension       Method PeekString:String( offset:Int, type:StringFormat )           Local ret:String = ""           Select type             Case StringFormat.ASCII                 Local len:Int = Self.Length - offset                 If len < 1 Then Return ""                   For Local i:Int = 0 Until len                     ret += String.FromChar( Self.PeekUByte(offset+i) )                 Next         End Select           Return ret     End       Method PeekString:String( offset:Int, count:Int, type:StringFormat )           Local ret:String = ""         Local len :Int           Select type             Case StringFormat.ASCII                 len = Self.Length - offset                 len = Min(len,count)                 If len < 1 Then Return ""                          For Local i:Int = 0 Until len                     ret += String.FromChar( Self.PeekUByte(offset+i) )                 Next         End Select           Return ret     End   End

[Danilo]

@jondecker76: Could it be that your expected results comes from routines that use SHA256() on ASCII strings? All std.digest functions in Monkey2 use 16-bit Unicode strings.

The SHA(), MD5(), SHA256() with Unicode string buffers are probably much different from using the same functions with ASCII buffers.

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