(Tcl) Ibanity HTTP Signature for XS2A, Isabel Connect, Ponto Connect

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Demonstrates how to add a Signature header for Ibanity HTTP requests.

For more information, see https://documentation.ibanity.com/http-signature

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load ./chilkat.dll

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

# In order to sign your HTTP requests, you have to add 2 headers to the HTTP request: Digest: the digest of the request payload and Signature: the actual signature of the request. 

# POST /xs2a/customer-access-tokens HTTP/1.1
# Host: api.ibanity.com
# Content-Type: application/json
# Digest: SHA-512=z4PhNX7vuL3xVChQ1m2AB9Yg5AULVxXcg/SpIdNs6c5H0NE8XYXysP+DGNKHfuwvY7kxvUdBeoGlODJ6+SfaPg==
# Ibanity-Idempotency-Key: 61f02718-eeee-46e1-b5eb-e8fd6e799c2d
# Signature: keyId="62f02718-eeee-46e1-b5eb-e8fd6e799c2e",created=1599659223,algorithm="hs2019",headers="(request-target) host digest (created) ibanity-idempotency-key",signature="SjWJWbWN7i0...zsbM="
# 
# {"data":{"type":"customerAccessToken", "attributes":{"applicationCustomerReference":"15874569"}}}

# The payload (body) of the above HTTP request is the JSON.
# Build the JSON above.
# Use this online tool to generate code from sample JSON: 
# Generate Code to Create JSON
set json [new_CkJsonObject]

CkJsonObject_UpdateString $json "data.type" "customerAccessToken"
CkJsonObject_UpdateString $json "data.attributes.applicationCustomerReference" "15874569"

set payload [CkJsonObject_emit $json]
puts "payload = $payload"

# Step 1: Build the (created) virtual header

set dtNow [new_CkDateTime]

CkDateTime_SetFromCurrentSystemTime $dtNow
set created [CkDateTime_getAsUnixTimeStr $dtNow 0]
puts "created = $created"

# Step 2: Build the Digest header
set crypt [new_CkCrypt2]

CkCrypt2_put_HashAlgorithm $crypt "sha512"
CkCrypt2_put_EncodingMode $crypt "base64"
CkCrypt2_put_Charset $crypt "utf-8"

set sbDigestHdrValue [new_CkStringBuilder]

CkStringBuilder_Append $sbDigestHdrValue "SHA-512="
CkStringBuilder_Append $sbDigestHdrValue [CkCrypt2_hashStringENC $crypt [CkJsonObject_emit $json]]

puts [CkStringBuilder_getAsString $sbDigestHdrValue]

# Step 3: Build the (request target) virtual header

# In order to build the signature you will need a virtual header named (request-target) (the parentheses are important). 
# The (request-target) is the string concatenation of the HTTP method (in lowercase) with the path and query parameters.
set request_target "post /xs2a/customer-access-tokens"

# Step 4: Build the signing string

# The signing string is the concatenation of the signed header names (in lowercase) and values separated by a LF.

# You must always sign the following headers: (request-target), host, (created), digest. 
# If used, you must also sign the authorization header and any ibanity-* headers, such as ibanity-idempotency-key. 

set sbSigningString [new_CkStringBuilder]

CkStringBuilder_Append $sbSigningString "(request-target): "
CkStringBuilder_AppendLine $sbSigningString $request_target 0
CkStringBuilder_Append $sbSigningString "host: "
CkStringBuilder_AppendLine $sbSigningString "api.ibanity.com" 0
CkStringBuilder_Append $sbSigningString "digest: "
CkStringBuilder_AppendLine $sbSigningString [CkStringBuilder_getAsString $sbDigestHdrValue] 0
CkStringBuilder_Append $sbSigningString "(created): "
CkStringBuilder_AppendLine $sbSigningString $created 0
CkStringBuilder_Append $sbSigningString "ibanity-idempotency-key: "
set idempotencyKey [CkCrypt2_generateUuid $crypt]
CkStringBuilder_Append $sbSigningString $idempotencyKey

# Step 5: Build the signed headers list

# To allow Ibanity to check the signed headers, you must provide a list of the header names. They should be lowercase and in the same order used to create the signing string. 
set signed_headers_list "(request-target) host digest (created) ibanity-idempotency-key"

# Step 6: Build the Signature header

# This is where the real signing happens. The signature header is a combination of several sub-headers -
# 
#     keyId: the identifier for the application's signature certificate, obtained from the Developer Portal
#     algorithm: the digital signature algorithm used to generate the signature (must be hs2019)
#     headers: The list of HTTP headers created in step 5
#     signature: the Base64-encoded digital signature of the signing string created in step 4.

set privKey [new_CkPrivateKey]

set success [CkPrivateKey_LoadEncryptedPemFile $privKey "my_ibanity_signature_private_key.pem" "pem_password"]
if {$success == 0} then {
    puts [CkPrivateKey_lastErrorText $privKey]
    delete_CkJsonObject $json
    delete_CkDateTime $dtNow
    delete_CkCrypt2 $crypt
    delete_CkStringBuilder $sbDigestHdrValue
    delete_CkStringBuilder $sbSigningString
    delete_CkPrivateKey $privKey
    exit
}

set rsa [new_CkRsa]

CkRsa_put_PssSaltLen $rsa 32
CkRsa_put_EncodingMode $rsa "base64"
# Use the RSASSA-PSS signature algorithm
CkRsa_put_OaepPadding $rsa 1

set success [CkRsa_ImportPrivateKeyObj $rsa $privKey]
if {$success == 0} then {
    puts [CkRsa_lastErrorText $rsa]
    delete_CkJsonObject $json
    delete_CkDateTime $dtNow
    delete_CkCrypt2 $crypt
    delete_CkStringBuilder $sbDigestHdrValue
    delete_CkStringBuilder $sbSigningString
    delete_CkPrivateKey $privKey
    delete_CkRsa $rsa
    exit
}

# Sign the signing string.
set sigBase64 [CkRsa_signStringENC $rsa [CkStringBuilder_getAsString $sbSigningString] "sha-256"]
if {[CkRsa_get_LastMethodSuccess $rsa] == 0} then {
    puts [CkRsa_lastErrorText $rsa]
    delete_CkJsonObject $json
    delete_CkDateTime $dtNow
    delete_CkCrypt2 $crypt
    delete_CkStringBuilder $sbDigestHdrValue
    delete_CkStringBuilder $sbSigningString
    delete_CkPrivateKey $privKey
    delete_CkRsa $rsa
    exit
}

# Build the signature header value.
set sbSigHeaderValue [new_CkStringBuilder]

CkStringBuilder_Append $sbSigHeaderValue "keyId=\""
# Use your identifier for the application's signature certificate, obtained from the Developer Portal
CkStringBuilder_Append $sbSigHeaderValue "62f02718-eeee-46e1-b5eb-e8fd6e799c2e"
CkStringBuilder_Append $sbSigHeaderValue "\",created="
CkStringBuilder_Append $sbSigHeaderValue $created
CkStringBuilder_Append $sbSigHeaderValue ",algorithm=\"hs2019\",headers=\""
CkStringBuilder_Append $sbSigHeaderValue $signed_headers_list
CkStringBuilder_Append $sbSigHeaderValue "\",signature=\""
CkStringBuilder_Append $sbSigHeaderValue $sigBase64
CkStringBuilder_Append $sbSigHeaderValue "\""

puts [CkStringBuilder_getAsString $sbSigHeaderValue]

delete_CkJsonObject $json
delete_CkDateTime $dtNow
delete_CkCrypt2 $crypt
delete_CkStringBuilder $sbDigestHdrValue
delete_CkStringBuilder $sbSigningString
delete_CkPrivateKey $privKey
delete_CkRsa $rsa
delete_CkStringBuilder $sbSigHeaderValue