Tcl

Verify JWT Using an ECC Public Key (ES256, ES384, ES512)

Demonstrates how to verify a JWT that was signed using an ECC private key.

This example verifies the ECC signature. It also does the following:

Checks to see if the time constraints ("nbf" and "exp") are valid.
Recovers the original JOSE header.
Recovers the original claims JSON.

Chilkat Tcl Downloads

Tcl


load ./chilkat.dll

set success 0

# Demonstrates how to verify an JWT using an ECC public key.

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

set pubKey [new_CkPublicKey]

set success [CkPublicKey_LoadFromFile $pubKey "qa_data/pem/ecc_public.pem"]

set jwt [new_CkJwt]

set token "eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDg1NzA4NzkyLCJuYmYiOjE0ODU3MDg3OTIsImV4cCI6MTQ4NTcxMjM5Mn0.wqsuyJpxJ073ox-lOiLFqG1lQocXe4hGf2XGZJRrO3qn0UusxI_bu3Gzky8gBsH4sA4u9TWZn5M-1wYMMIJk6Q"

# First verify the signature.
set sigVerified [CkJwt_VerifyJwtPk $jwt $token $pubKey]
puts "verified: $sigVerified"

# Let's see if the time constraints, if any, are valid.
# The above JWT was created on the afternoon of 16-May-2016, with an expiration of 1 hour.
# If the current system time is before the "nbf" time, or after the "exp" time,
# then IsTimeValid will return false/0.
# Also, we'll allow a leeway of 60 seconds to account for any clock skew.
# Note: If the token has no "nbf" or "exp" claim fields, then IsTimeValid is always true.
set leeway 60
set bTimeValid [CkJwt_IsTimeValid $jwt $token $leeway]
puts "time constraints valid: $bTimeValid"

# Now let's recover the original claims JSON (the payload).
set payload [CkJwt_getPayload $jwt $token]
# The payload will likely be in compact form:
puts "$payload"

# We can format for human viewing by loading it into Chilkat's JSON object
# and emit.
set json [new_CkJsonObject]

set success [CkJsonObject_Load $json $payload]
CkJsonObject_put_EmitCompact $json 0
puts [CkJsonObject_emit $json]

# We can recover the original JOSE header in the same way:
set joseHeader [CkJwt_getHeader $jwt $token]
# The payload will likely be in compact form:
puts "$joseHeader"

# We can format for human viewing by loading it into Chilkat's JSON object
# and emit.
set success [CkJsonObject_Load $json $joseHeader]
CkJsonObject_put_EmitCompact $json 0
puts [CkJsonObject_emit $json]

delete_CkPublicKey $pubKey
delete_CkJwt $jwt
delete_CkJsonObject $json