(Tcl) Validate JWS Using RSASSA-PKCS1-v1_5 SHA-256

Validates a JSON Web Signature (JWS) that uses RSASSA-PKCS1-v1_5 SHA-256.

Note: This example requires Chilkat v9.5.0.66 or greater.

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load ./chilkat.dll

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

# Note: This example requires Chilkat v9.5.0.66 or greater.

# This example takes a JSON signature in compact serialization format,
# and uses an RSA public key to validate and recover the protected header and payload.

# We only need a public key for signature validation.  This is the RSA public key
# that is used:

#      {"kty":"RSA", 
#       "n":"ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx
#            HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs
#            D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH
#            SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV
#            MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8
#            NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ", 
#       "e":"AQAB"
#      }

set sbPubKey [new_CkStringBuilder]

CkStringBuilder_Append $sbPubKey "{\"kty\":\"RSA\","
CkStringBuilder_Append $sbPubKey "\"n\":\"ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx"
CkStringBuilder_Append $sbPubKey "HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs"
CkStringBuilder_Append $sbPubKey "D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH"
CkStringBuilder_Append $sbPubKey "SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV"
CkStringBuilder_Append $sbPubKey "MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8"
CkStringBuilder_Append $sbPubKey "NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ\","
CkStringBuilder_Append $sbPubKey "\"e\":\"AQAB\""
CkStringBuilder_Append $sbPubKey "}"

set pubKey [new_CkPublicKey]

set success [CkPublicKey_LoadFromString $pubKey [CkStringBuilder_getAsString $sbPubKey]]
if {$success != 1} then {
    puts [CkPublicKey_lastErrorText $pubKey]
    delete_CkStringBuilder $sbPubKey
    delete_CkPublicKey $pubKey
    exit
}

set jws [new_CkJws]

# Set the RSA public key:
set signatureIndex 0
CkJws_SetPublicKey $jws $signatureIndex $pubKey

# Load the JWS.
set sbJws [new_CkStringBuilder]

CkStringBuilder_Append $sbJws "eyJhbGciOiJSUzI1NiJ9"
CkStringBuilder_Append $sbJws "."
CkStringBuilder_Append $sbJws "eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt"
CkStringBuilder_Append $sbJws "cGxlLmNvbS9pc19yb290Ijp0cnVlfQ"
CkStringBuilder_Append $sbJws "."
CkStringBuilder_Append $sbJws "cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZmh7"
CkStringBuilder_Append $sbJws "AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjbKBYNX4"
CkStringBuilder_Append $sbJws "BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHlb1L07Qe7K"
CkStringBuilder_Append $sbJws "0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZESc6BfI7noOPqv"
CkStringBuilder_Append $sbJws "hJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AXLIhWkWywlVmtVrB"
CkStringBuilder_Append $sbJws "p0igcN_IoypGlUPQGe77Rw"

set success [CkJws_LoadJwsSb $jws $sbJws]
if {$success != 1} then {
    puts [CkJws_lastErrorText $jws]
    delete_CkStringBuilder $sbPubKey
    delete_CkPublicKey $pubKey
    delete_CkJws $jws
    delete_CkStringBuilder $sbJws
    exit
}

# Validate the 1st (and only) signature at index 0..
set v [CkJws_Validate $jws $signatureIndex]
if {$v < 0} then {
    # Perhaps Chilkat was not unlocked or the trial expired..
    puts "Method call failed for some other reason."
    puts [CkJws_lastErrorText $jws]
    delete_CkStringBuilder $sbPubKey
    delete_CkPublicKey $pubKey
    delete_CkJws $jws
    delete_CkStringBuilder $sbJws
    exit
}

if {$v == 0} then {
    puts "Invalid signature.  The RSA key was incorrect, the JWS was invalid, or both."
    delete_CkStringBuilder $sbPubKey
    delete_CkPublicKey $pubKey
    delete_CkJws $jws
    delete_CkStringBuilder $sbJws
    exit
}

# If we get here, the signature was validated..
puts "Signature validated."
puts "--"

# Recover the original content:
puts "Recovered content:"
puts [CkJws_getPayload $jws utf-8]
puts "--"

# Examine the protected header:
# joseHeader is a CkJsonObject
set joseHeader [CkJws_GetProtectedHeader $jws $signatureIndex]
if {[CkJws_get_LastMethodSuccess $jws] != 1} then {
    puts "No protected header found at the given index."
    delete_CkStringBuilder $sbPubKey
    delete_CkPublicKey $pubKey
    delete_CkJws $jws
    delete_CkStringBuilder $sbJws
    exit
}

CkJsonObject_put_EmitCompact $joseHeader 0

puts "Protected (JOSE) header:"
puts [CkJsonObject_emit $joseHeader]
delete_CkJsonObject $joseHeader

# Output:

# 	Signature validated.
# 	--
# 	Recovered content:
# 	{"iss":"joe", 
# 	 "exp":1300819380,
# 	 "http://example.com/is_root":true}
# 	--
# 	Protected (JOSE) header:
# 	{ 
# 	  "alg": "RS256"
# 	}

delete_CkStringBuilder $sbPubKey
delete_CkPublicKey $pubKey
delete_CkJws $jws
delete_CkStringBuilder $sbJws