(Tcl) Create JWT Using HS256, HS384, or HS512

Demonstrates how to create a JWT using HS256, HS384, or HS512. (HS256 is JWT's acronym for HMAC-SHA256.) When HMAC is used, the secret is a shared secret (i.e. password) that both client and server know beforehand.

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 an HMAC JWT using a shared secret (password).

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

set jwt [new_CkJwt]

# Build the JOSE header
set jose [new_CkJsonObject]

# Use HS256.  Pass the string "HS384" or "HS512" to use a different algorithm.
set success [CkJsonObject_AppendString $jose "alg" "HS256"]
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

set strJwt [CkJwt_createJwt $jwt [CkJsonObject_emit $jose] [CkJsonObject_emit $claims] "secret"]

puts "$strJwt"

delete_CkJwt $jwt
delete_CkJsonObject $jose
delete_CkJsonObject $claims