(Tcl) Walmart Partner API Authentication (Generate a Signature for a Request)

Demonstrates how to generate a signature for a Walmart Partner REST API call.

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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.

set consumerId "b68d2a72...."
set baseUrl "https://marketplace.walmartapis.com/v2/feeds"
# This is your Base64 encoded private key
set privateEncodedStr "MIICeAIBADANBgkqhkiG9w0BAQEFAA......"
set httpMethod "GET"

# We need a timestamp in decimal string form representing the number of milliseconds since Jan 01 1970 UTC.
set dt [new_CkDateTime]

# Set bLocal = 1 for a timestamp in the local timezone.  Set bLocal = 0 for a UTC timestamp.
set bLocal 0
# This gets the timestamp in seconds, not milliseconds.
set timeStampVal [CkDateTime_GetAsUnixTime $dt $bLocal]

# Build the string to sign.
set sbStringToSign [new_CkStringBuilder]

CkStringBuilder_Append $sbStringToSign $consumerId
CkStringBuilder_Append $sbStringToSign "\n"
CkStringBuilder_Append $sbStringToSign $baseUrl
CkStringBuilder_Append $sbStringToSign "\n"
CkStringBuilder_Append $sbStringToSign $httpMethod
CkStringBuilder_Append $sbStringToSign "\n"
CkStringBuilder_AppendInt $sbStringToSign $timeStampVal
# We add three zero's so that the timestamp value is in milliseconds.
# We don't care about accuracy down to less than a second.
# All the server cares about is that the request was signed at the current date/time
# within some reasonable margin of error (to account for systems having clocks
# that may be slightly different).
CkStringBuilder_Append $sbStringToSign "000\n"

set privKey [new_CkPrivateKey]

# Load the private key into a private key object.
# Note: Technically the private key is not PEM because it lacks the header/footer strings
# used for PEM.  However, the LoadPem method will still accept it and load it correctly.
set success [CkPrivateKey_LoadPem $privKey $privateEncodedStr]
if {$success != 1} then {
    puts [CkPrivateKey_lastErrorText $privKey]
    delete_CkDateTime $dt
    delete_CkStringBuilder $sbStringToSign
    delete_CkPrivateKey $privKey
    exit
}

set rsa [new_CkRsa]

set success [CkRsa_ImportPrivateKeyObj $rsa $privKey]
if {$success != 1} then {
    puts [CkRsa_lastErrorText $rsa]
    delete_CkDateTime $dt
    delete_CkStringBuilder $sbStringToSign
    delete_CkPrivateKey $privKey
    delete_CkRsa $rsa
    exit
}

# We want a base64 signature string.
CkRsa_put_EncodingMode $rsa "base64"

set signatureString [CkRsa_signStringENC $rsa [CkStringBuilder_getAsString $sbStringToSign] "SHA256"]
if {[CkRsa_get_LastMethodSuccess $rsa] != 1} then {
    puts [CkRsa_lastErrorText $rsa]
    delete_CkDateTime $dt
    delete_CkStringBuilder $sbStringToSign
    delete_CkPrivateKey $privKey
    delete_CkRsa $rsa
    exit
}

puts "Signature String: $signatureString"

delete_CkDateTime $dt
delete_CkStringBuilder $sbStringToSign
delete_CkPrivateKey $privKey
delete_CkRsa $rsa