Tcl

Create XML Signature with External Data Reference

See more XML Digital Signatures Examples

Demonstrates how to create an XML digital signature where the data is external. In this case, the data is a JPG file.

This example requires Chilkat v9.5.0.69 or greater.

Tcl

load ./chilkat.dll

set success 0

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

# This example inserts an XML signature in the following XML:

# <?xml version="1.0" encoding="UTF-8" standalone="no"?>
# <abc>
#   <xyz>
#     <jpg>
#         <name>starfish.jpg</name>
#         <url>https://www.chilkatsoft.com/images/starfish.jpg</url>
#     </jpg>
#   </xyz>
# </abc>

# The above XML is available at https://www.chilkatsoft.com/exampleData/addSignatureToThis.xml
# First fetch the XML:

set url "https://www.chilkatsoft.com/exampleData/addSignatureToThis.xml"
set http [new_CkHttp]

set sbXml [new_CkStringBuilder]

set success [CkHttp_QuickGetSb $http $url $sbXml]
if {$success != 1} then {
    puts [CkHttp_lastErrorText $http]
    delete_CkHttp $http
    delete_CkStringBuilder $sbXml
    exit
}

# We'll use an RSA private key for signing.  
set rsaKey [new_CkPrivateKey]

set success [CkPrivateKey_LoadPemFile $rsaKey "qa_data/rsa/rsaPrivKey_pkcs8.pem"]
if {$success != 1} then {
    puts [CkPrivateKey_lastErrorText $rsaKey]
    delete_CkHttp $http
    delete_CkStringBuilder $sbXml
    delete_CkPrivateKey $rsaKey
    exit
}

set xmlSigGen [new_CkXmlDSigGen]

# Indicate were the Signature will be inserted:
CkXmlDSigGen_put_SigLocation $xmlSigGen "abc|xyz|jpg"

# Provide the RSA key to be used for signing:
CkXmlDSigGen_SetPrivateKey $xmlSigGen $rsaKey

# Fetch the JPG image data.
set jpgUrl "https://www.chilkatsoft.com/images/starfish.jpg"
set jpgData [new_CkBinData]

set success [CkHttp_QuickGetBd $http $jpgUrl $jpgData]
if {$success != 1} then {
    puts [CkHttp_lastErrorText $http]
    delete_CkHttp $http
    delete_CkStringBuilder $sbXml
    delete_CkPrivateKey $rsaKey
    delete_CkXmlDSigGen $xmlSigGen
    delete_CkBinData $jpgData
    exit
}

# Add the external data reference:
CkXmlDSigGen_AddExternalBinaryRef $xmlSigGen $jpgUrl $jpgData "sha256" ""

# Create the XML digital signature:
set success [CkXmlDSigGen_CreateXmlDSigSb $xmlSigGen $sbXml]
if {$success != 1} then {
    puts [CkXmlDSigGen_lastErrorText $xmlSigGen]
    delete_CkHttp $http
    delete_CkStringBuilder $sbXml
    delete_CkPrivateKey $rsaKey
    delete_CkXmlDSigGen $xmlSigGen
    delete_CkBinData $jpgData
    exit
}

# Examine the XML that now contains the Signature:
puts [CkStringBuilder_getAsString $sbXml]

# <?xml version="1.0" encoding="UTF-8" standalone="no"?>
# <abc>
#   <xyz>
#     <jpg>
#         <name>starfish.jpg</name>
#         <url>https://www.chilkatsoft.com/images/starfish.jpg</url>
#     <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/><ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/><ds:Reference URI="https://www.chilkatsoft.com/images/starfish.jpg"><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>AOU810yJV5Np/DnO29qpObqiTSTTCDvxGsX5ayiTYXI=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>ApHRr6nilNrzt3dLveC9zlPoSllaCMfHsbAwr+vYBPkHkJ4wD5LzDDhi1tSJZAAeTckmvSqIG3Wi0rgXQiSM644MD3coBFx4QgrY+GZ+XJJE2Y0Ye3VvaQBiRdUW3INGsW4GLubncgQk5JhuAQjo6O/GKpfEuYqUJj/6CLHLQwMPwbZ2043ykgzuPFoOZf6EydJMBAn1ORMvrpUn+zuA9UngOTGap6eWE4CeiNx23BRC2wSztbUjdCLcqXvgiYu/v0tBNaTcwy7b6+IFtwv/lNUUBUQJ/3p+aErzFn3wLeH3yeqpDCU0U6Dqu5SS1jYupcWWsLHJjYnj2066DPJi/g==</ds:SignatureValue><ds:KeyInfo><ds:KeyValue><ds:RSAKeyValue><ds:Modulus>sXeRhM55P13FbpNcXAMR3olbw2Wa6keZIHu5YTZYUBTlYWId+pNiwUz3zFIEo+0IfYR0H27ybIycQO+1IIzJofUFNMAL3tZps2OKPlsjuCPls6kXpXhv/gvhux8LrCtp4PcKWqJ6QVOZKChc7WAx40qFWzHi57ueqRTv3x0kESqGg/VjsqyTEvb55psJO2RsfhLT7+YVh3hImRM3RDaJdkTkPuOxeFyT6N7VXD09329sLuS3QkUbE9zEKDnz9X3d8dEQdJhSI9ba5fxl8R7fu8pB67ElfzFml96X1jLFtzy1pzOT5Fc4ROcaqlYckVzdBq9sxezm6MYmDBjNAcibRw==</ds:Modulus><ds:Exponent>AQAB</ds:Exponent></ds:RSAKeyValue></ds:KeyValue></ds:KeyInfo></ds:Signature></jpg>
#   </xyz>
# </abc>
# 

delete_CkHttp $http
delete_CkStringBuilder $sbXml
delete_CkPrivateKey $rsaKey
delete_CkXmlDSigGen $xmlSigGen
delete_CkBinData $jpgData