(Tcl) Create JWT Using RSA (RS256, RS384, or RS512)

Demonstrates how to create a JWT using an RSA private key. This is for JOSE headers with an "alg" of RS256, RS384, or RS512. When RSA is used, the private key signs (creates) the JWT, and the public key is for verification.

This example also demonstrates how to include time constraints:

• nbf: Not Before Time
• exp: Expiration Time
• iat: Issue At Time

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load ./chilkat.dll

# Demonstrates how to create a JWT using an RSA private key.

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

set privKey [new_CkPrivateKey]

# Load an RSA private key from a PEM file.
set success [CkPrivateKey_LoadEncryptedPemFile $privKey "qa_data/pem/rsa_passwd.pem" "passwd"]
if {$success != 1} then {
    puts [CkPrivateKey_lastErrorText $privKey]
    delete_CkPrivateKey $privKey
    exit
}

set jwt [new_CkJwt]

# Build the JOSE header
set jose [new_CkJsonObject]

# Use RS256.  Pass the string "RS384" or "RS512" to use RSA with SHA-384 or SHA-512.
set success [CkJsonObject_AppendString $jose "alg" "RS256"]
set success [CkJsonObject_AppendString $jose "typ" "JWT"]

# Now build the JWT claims (also known as the payload)
set claims [new_CkJsonObject]

set success [CkJsonObject_AppendString $claims "iss" "http://example.org"]
set success [CkJsonObject_AppendString $claims "sub" "John"]
set success [CkJsonObject_AppendString $claims "aud" "http://example.com"]

# Set the timestamp of when the JWT was created to now.
set curDateTime [CkJwt_GenNumericDate $jwt 0]
set success [CkJsonObject_AddIntAt $claims -1 "iat" $curDateTime]

# Set the "not process before" timestamp to now.
set success [CkJsonObject_AddIntAt $claims -1 "nbf" $curDateTime]

# Set the timestamp defining an expiration time (end time) for the token
# to be now + 1 hour (3600 seconds)
set success [CkJsonObject_AddIntAt $claims -1 "exp" [expr $curDateTime + 3600]]

# Produce the smallest possible JWT:
CkJwt_put_AutoCompact $jwt 1

# Create the JWT token.  This is where the RSA signature is created.
set token [CkJwt_createJwtPk $jwt [CkJsonObject_emit $jose] [CkJsonObject_emit $claims] $privKey]

puts "$token"

delete_CkPrivateKey $privKey
delete_CkJwt $jwt
delete_CkJsonObject $jose
delete_CkJsonObject $claims