Android Question Signature and Digest for XML

[Angelo Messina]

Hi, what do you suggest for signing XML files, having only the certificate and the CRS issued by the revenue agency to transmit the monthly sales amounts using only B4A.

What do you advise me to do? I'm in trouble I have to deliver a job and I only need this part.

Thank you

 

[Erel]

You can use the Encryption library to sign data. You need to first find out which specific algorithm should be used.

 

[Angelo Messina]

SHA256

SHA256RSA

 

[Erel]

Signature object documentation: https://www.b4x.com/android/help/encryption.html#signature

Example: https://www.b4x.com/android/forum/threads/calculate-the-java-security-key.73591/#post-467597

 

[Angelo Messina]

thanks for your kind reply, a practical example to generate a DigestValue what to use as text to pass and what to do to generate the SignatureValue. I've been stuck on this for a month.

 

[KMatle]

thanks for your kind reply, a practical example to generate a DigestValue what to use as text to pass and what to do to generate the SignatureValue. I've been stuck on this for a month.

Did you do a Google search? Can you provide more infos about what they expect? (api, xml format, docs)?

 

[Angelo Messina]

y = y.create("RichiestaCertificatoDispositivo").attribute("xmlns:ds","http://www.w3.org/2000/09/xmldsig#").attribute("xmlns:p","http://ivaservizi.agenziaentrate.gov.it/docs/xsd/corrispettivi/v1.0").attribute("xmlns:xsi","http://www.w3.org/2001/XMLSchema-instance") _
    .element("Csr").text(CSR).up _
    .element("Dispositivo") _
    .element("Tipo").text("DM").up.up.up _
    .element("TecnicoVerificatore") _
    .element("CodiceFiscale").text(CodiceFiscale).up _
    .element("PIvaSocieta") _
    .element("IdPaese").text("IT").up _
    .element("IdCodice").text(CodiceDitta).up.up.up _
    .element("ds:Signature").attribute("xmlns:ds","http://www.w3.org/2000/09/xmldsig#") _
    .element("ds:SignedInfo") _
    .element("ds:CanonicalizationMethod").attribute("Algorithm","http://www.w3.org/TR/2001/REC-xml-c14n-20010315").up _
    .element("ds:SignatureMethod").attribute("Algorithm","http://www.w3.org/2001/04/xmldsig-more#rsa-sha256").up _
    .element("ds:Reference").attribute("URI","") _
    .element("ds:Transforms") _
    .element("ds:Transform").attribute("Algorithm","http://www.w3.org/2000/09/xmldsig#enveloped-signature").up.up _
    .element("ds:DigestMethod").attribute("Algorithm","http://www.w3.org/2001/04/xmlenc#sha256").up _
    .element("ds:DigestValue").text(DigestValue).up.up.up _
    .element("ds:SignatureValue").text(SignatureValue).up _
    .element("ds:KeyInfo") _
    .element("ds:X509Data") _
    .element("ds:X509Certificate").text(x509).up

<?xml version="1.0" encoding="ISO-8859-1"?>
<p:RichiestaCertificatoDispositivo xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://ivaservizi.agenziaentrate.gov.it/docs/xsd/corrispettivi/v1.0" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" versione="1.0">
<Csr>MII......==</Csr>
<Dispositivo>
<Tipo>DM</Tipo>
</Dispositivo>
<TecnicoVerificatore>
<CodiceFiscale>XXXXXXXXXXXXXXXY</CodiceFiscale>
<PIvaSocieta>
<IdPaese>IT</IdPaese>
<IdCodice>09999999999</IdCodice>
</PIvaSocieta>
</TecnicoVerificatore>
<ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
<ds:SignedInfo>
<ds:CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
<ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/>
<ds:Reference URI="">
<ds:Transforms>
<ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
</ds:Transforms>
<dsigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
<dsigestValue> How to do this </dsigestValue>
</ds:Reference>
</ds:SignedInfo>
<ds:SignatureValue> how to calculate this</ds:SignatureValue>
<ds:KeyInfo>
<ds:X509Data>
<ds:X509Certificate>MIIE.....</ds:X509Certificate>
</ds:X509Data>
</ds:KeyInfo>
</ds:Signature>
</p:RichiestaCertificatoDispositivo>

 

[Angelo Messina]

I don't know how to do these 2 points and I have been at a standstill for 1 month. Thanks for any advice!

 

[Erel]

The exact details depend on your specific requirements.
You can convert the text to bytes with:

Dim data() As Byte = YourString.GetBytes("utf8")

 

[Angelo Messina]

ok

 

[Angelo Messina]

But what to take to do the DigestValue?

and what is the sequence to generate the SignatureValue?

 

[DonManfred]

But what to take to do the DigestValue?

and what is the sequence to generate the SignatureValue?

The exact details depend on your specific requirements.

Can you provide more infos about what they expect? (api, xml format, docs)?

 

[Angelo Messina]

Dim strCanonData As String
    Dim abMessage() As Byte
    Dim BC As ByteConverter
    Dim DigestValue As String
    
    strCanonData = Testo.Replace( CRLF, Chr(10))
    strCanonData = "<Object xmlns=""http://www.w3.org/2000/09/xmldsig#"" Id=""object"">" & strCanonData & "</Object>"
    Log( "CANON DATA='" & strCanonData & "'")
    abMessage = BC.StringToBytes(strCanonData, "UTF8")
    Log( "HEX(DATA)=" & BC.HexFromBytes(abMessage))
    'Digest = BC.HexFromBytes(abMessage)
    nativeMe.InitializeContext
    DigestValue = Encode64(nativeMe.RunMethod("getSHA256",Array(strCanonData)))
    Return DigestValue

 

[Angelo Messina]

Is this method right?

to get in DigestValue

 

[Erel]

No. You should use MessageDigest from the Encryption library.

 

[Angelo Messina]

Please can you show me a concrete exampleto use MessageDigest from the Encryption library.

    Dim strCanonData As String
    Dim abMessage() As Byte
    Dim BC As ByteConverter
    Dim DigestValue As String
    Dim Enc As MessageDigest
    Dim Testo As String =  "Corrispettivielettronici/Out/Richiesta.xml"
    strCanonData = Testo.Replace( CRLF, Chr(10))
   
strCanonData = "<Object xmlns=""http://www.w3.org/2000/09/xmldsig#"" Id=""object"">" & strCanonData & "</Object>"
       
    abMessage = BC.StringToBytes(strCanonData, "UTF8")
   
    DigestValue = BC.StringFromBytes( Enc.GetMessageDigest(abMessage, "SHA-256"),"UTF8")
    Log("Digest " & DigestValue)

 

[Erel]

Never convert raw bytes to string.

Use StringUtils.EncodeBase64 to convert the bytes to string.

 

[Angelo Messina]

    Dim strCanonData As String
    Dim abMessage() As Byte
    Dim BC As ByteConverter
    Dim DigestValue As String
    Dim Enc As MessageDigest
    Dim su As StringUtils
    Dim Testo As String =  "Corrispettivielettronici/Out/Richiesta.xml"
    
    strCanonData = Testo.Replace( CRLF, Chr(10))
    strCanonData = "<Object xmlns=""http://www.w3.org/2000/09/xmldsig#"" Id=""object"">" & strCanonData & "</Object>"
    
    Log( "CANON DATA='" & strCanonData & "'")
    
    abMessage = BC.StringToBytes(strCanonData, "UTF8")
    DigestValue = su.EncodeBase64(Enc.GetMessageDigest(abMessage, "SHA-256"))

    Log("Digest " & DigestValue )

right so?

 

[Angelo Messina]

can you show me the way for the Signature Value?

 Dim Appoggio As String
 Dim strSignature64 As String
 Dim strSignedInfoCanonic As String
 Dim BC As ByteConverter
 Dim su As StringUtils
 Dim En As Signature
strSignedInfoCanonic = "<SignedInfo xmlns=""http://www.w3.org/2000/09/xmldsig#"">" & CRLF & _
            "  <CanonicalizationMethod Algorithm=""http://www.w3.org/TR/2001/REC-xml-c14n-20010315""></CanonicalizationMethod>" & CRLF & _
            "  <SignatureMethod Algorithm=""http://www.w3.org/2001/04/xmldsig-more#rsa-sha256""></SignatureMethod>" & CRLF & _
            "  <Reference URI=""#object"">" & CRLF & _
            "    <DigestMethod Algorithm=""http://www.w3.org/2001/04/xmlenc#sha256""></DigestMethod>" & CRLF & _
            "    <DigestValue>" & strDigestBase64 & "</DigestValue>" & CRLF & _
            "  </Reference>" & CRLF & _
            "</SignedInfo>"

    abMessage = BC.StringToBytes(strSignedInfoCanonic, "UTF8")
   
   
    En.Update(abMessage)

 

[Erel]

I posted a link to an example in a previous post of mine.