(Tcl) Verify JWT with EdDSA / Ed25519 Signature

Note: This example requires Chilkat v9.5.0.84 or greater.

Demonstrates how to verify a JWT that was signed using an Ed25519 private key.

This example verifies the EdDSA 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 data.

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load ./chilkat.dll

# Demonstrates how to verify a JWT with an EdDSA/Ed25519 Signature
# *** Requires Chilkat v9.5.0.84 or greater.

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

# Use this Ed25519 public key for verification

set jsonPubKey "{\"kty\": \"OKP\",\"alg\": \"EdDSA\",\"crv\": \"Ed25519\",\"x\": \"11qYAYKxCrfVS_7TyWQHOg7hcvPapiMlrwIaaPcHURo\"}"

set pubKey [new_CkPublicKey]

set success [CkPublicKey_LoadFromString $pubKey $jsonPubKey]
if {$success == 0} then {
    puts [CkPublicKey_lastErrorText $pubKey]
    delete_CkPublicKey $pubKey
    exit
}

set jwt [new_CkJwt]

set token "eyJhbGciOiJFZERTQSJ9.RXhhbXBsZSBvZiBFZDI1NTE5IHNpZ25pbmc.hgyY0il_MGCjP0JzlnLWG1PPOt7-09PGcvMg3AIbQR6dWbhijcNR4ki4iylGjg5BhVsPt9g7sVvpAr_MuM0KAg"

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

if {$sigVerified == 0} then {
    puts [CkJwt_lastErrorText $jwt]
    delete_CkPublicKey $pubKey
    delete_CkJwt $jwt
    exit
}

# 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"

# Recover the original data (the payload).
set payload [CkJwt_getPayload $jwt $token]
puts "$payload"

# Recover the original JOSE header in the same way:
set joseHeader [CkJwt_getHeader $jwt $token]
puts "$joseHeader"

delete_CkPublicKey $pubKey
delete_CkJwt $jwt