(Tcl) JWS Using RSASSA-PSS using SHA-256 and MGF1 with SHA-256

Creates and validates a JSON Web Signature (JWS) using RSASSA-PSS using SHA-256 and MGF1 with SHA-256.

Chilkat supports all of the following JWS algorithms:

   +--------------+-------------------------------+--------------------+
   | "alg" Param  | Digital Signature or MAC      | Implementation     |
   | Value        | Algorithm                     | Requirements       |
   +--------------+-------------------------------+--------------------+
   | HS256        | HMAC using SHA-256            | Required           |
   | HS384        | HMAC using SHA-384            | Optional           |
   | HS512        | HMAC using SHA-512            | Optional           |
   | RS256        | RSASSA-PKCS1-v1_5 using       | Recommended        |
   |              | SHA-256                       |                    |
   | RS384        | RSASSA-PKCS1-v1_5 using       | Optional           |
   |              | SHA-384                       |                    |
   | RS512        | RSASSA-PKCS1-v1_5 using       | Optional           |
   |              | SHA-512                       |                    |
   | ES256        | ECDSA using P-256 and SHA-256 | Recommended+       |
   | ES384        | ECDSA using P-384 and SHA-384 | Optional           |
   | ES512        | ECDSA using P-521 and SHA-512 | Optional           |
   | PS256        | RSASSA-PSS using SHA-256 and  | Optional           |
   |              | MGF1 with SHA-256             |                    |
   | PS384        | RSASSA-PSS using SHA-384 and  | Optional           |
   |              | MGF1 with SHA-384             |                    |
   | PS512        | RSASSA-PSS using SHA-512 and  | Optional           |
   |              | MGF1 with SHA-512             |                    |
   +--------------+-------------------------------+--------------------+

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.

# Use the following RSA key loaded from JWK format.
set sbJwk [new_CkStringBuilder]

CkStringBuilder_Append $sbJwk "{\"kty\":\"RSA\","
CkStringBuilder_Append $sbJwk "\"n\":\"ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx"
CkStringBuilder_Append $sbJwk "HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs"
CkStringBuilder_Append $sbJwk "D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH"
CkStringBuilder_Append $sbJwk "SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV"
CkStringBuilder_Append $sbJwk "MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8"
CkStringBuilder_Append $sbJwk "NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ\","
CkStringBuilder_Append $sbJwk "\"e\":\"AQAB\","
CkStringBuilder_Append $sbJwk "\"d\":\"Eq5xpGnNCivDflJsRQBXHx1hdR1k6Ulwe2JZD50LpXyWPEAeP88vLNO97I"
CkStringBuilder_Append $sbJwk "jlA7_GQ5sLKMgvfTeXZx9SE-7YwVol2NXOoAJe46sui395IW_GO-pWJ1O0"
CkStringBuilder_Append $sbJwk "BkTGoVEn2bKVRUCgu-GjBVaYLU6f3l9kJfFNS3E0QbVdxzubSu3Mkqzjkn"
CkStringBuilder_Append $sbJwk "439X0M_V51gfpRLI9JYanrC4D4qAdGcopV_0ZHHzQlBjudU2QvXt4ehNYT"
CkStringBuilder_Append $sbJwk "CBr6XCLQUShb1juUO1ZdiYoFaFQT5Tw8bGUl_x_jTj3ccPDVZFD9pIuhLh"
CkStringBuilder_Append $sbJwk "BOneufuBiB4cS98l2SR_RQyGWSeWjnczT0QU91p1DhOVRuOopznQ\","
CkStringBuilder_Append $sbJwk "\"p\":\"4BzEEOtIpmVdVEZNCqS7baC4crd0pqnRH_5IB3jw3bcxGn6QLvnEtfdUdi"
CkStringBuilder_Append $sbJwk "YrqBdss1l58BQ3KhooKeQTa9AB0Hw_Py5PJdTJNPY8cQn7ouZ2KKDcmnPG"
CkStringBuilder_Append $sbJwk "BY5t7yLc1QlQ5xHdwW1VhvKn-nXqhJTBgIPgtldC-KDV5z-y2XDwGUc\","
CkStringBuilder_Append $sbJwk "\"q\":\"uQPEfgmVtjL0Uyyx88GZFF1fOunH3-7cepKmtH4pxhtCoHqpWmT8YAmZxa"
CkStringBuilder_Append $sbJwk "ewHgHAjLYsp1ZSe7zFYHj7C6ul7TjeLQeZD_YwD66t62wDmpe_HlB-TnBA"
CkStringBuilder_Append $sbJwk "-njbglfIsRLtXlnDzQkv5dTltRJ11BKBBypeeF6689rjcJIDEz9RWdc\","
CkStringBuilder_Append $sbJwk "\"dp\":\"BwKfV3Akq5_MFZDFZCnW-wzl-CCo83WoZvnLQwCTeDv8uzluRSnm71I3Q"
CkStringBuilder_Append $sbJwk "CLdhrqE2e9YkxvuxdBfpT_PI7Yz-FOKnu1R6HsJeDCjn12Sk3vmAktV2zb"
CkStringBuilder_Append $sbJwk "34MCdy7cpdTh_YVr7tss2u6vneTwrA86rZtu5Mbr1C1XsmvkxHQAdYo0\","
CkStringBuilder_Append $sbJwk "\"dq\":\"h_96-mK1R_7glhsum81dZxjTnYynPbZpHziZjeeHcXYsXaaMwkOlODsWa"
CkStringBuilder_Append $sbJwk "7I9xXDoRwbKgB719rrmI2oKr6N3Do9U0ajaHF-NKJnwgjMd2w9cjz3_-ky"
CkStringBuilder_Append $sbJwk "NlxAr2v4IKhGNpmM5iIgOS1VZnOZ68m6_pbLBSp3nssTdlqvd0tIiTHU\","
CkStringBuilder_Append $sbJwk "\"qi\":\"IYd7DHOhrWvxkwPQsRM2tOgrjbcrfvtQJipd-DlcxyVuuM9sQLdgjVk2o"
CkStringBuilder_Append $sbJwk "y26F0EmpScGLq2MowX7fhd_QJQ3ydy5cY7YIBi87w93IKLEdfnbJtoOPLU"
CkStringBuilder_Append $sbJwk "W0ITrJReOgo1cq9SbsxYawBgfp_gh6A5603k2-ZQwVK0JKSHuLFkuQ3U\""
CkStringBuilder_Append $sbJwk "}"

set rsaKey [new_CkPrivateKey]

# Note: This example loads the RSA key from JWK format.  Any format can be loaded
# into the private key object. (See the online reference documentation..)
set success [CkPrivateKey_LoadJwk $rsaKey [CkStringBuilder_getAsString $sbJwk]]
if {$success != 1} then {
    puts [CkPrivateKey_lastErrorText $rsaKey]
    delete_CkStringBuilder $sbJwk
    delete_CkPrivateKey $rsaKey
    exit
}

# Create the JWS Protected Header
set jwsProtHdr [new_CkJsonObject]

CkJsonObject_AppendString $jwsProtHdr "alg" "PS256"

set jws [new_CkJws]

# Set the protected header:
set signatureIndex 0
CkJws_SetProtectedHeader $jws $signatureIndex $jwsProtHdr

# Set the RSA key:
CkJws_SetPrivateKey $jws $signatureIndex $rsaKey

# Set the payload.
set bIncludeBom 0
set payloadStr "In our village, folks say God crumbles up the old moon into stars."
CkJws_SetPayload $jws $payloadStr "utf-8" $bIncludeBom

# Create the JWS
# By default, the compact serialization is used.
set jwsCompact [CkJws_createJws $jws]
if {[CkJws_get_LastMethodSuccess $jws] != 1} then {
    puts [CkJws_lastErrorText $jws]
    delete_CkStringBuilder $sbJwk
    delete_CkPrivateKey $rsaKey
    delete_CkJsonObject $jwsProtHdr
    delete_CkJws $jws
    exit
}

puts "JWS: $jwsCompact"

# Note: RSA PSS padding uses random values, so the output will be different each time a signature is produced.
# sample output:
# JWS: eyJhbGciOiJQUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.TRWhwRo5dMv9-8OzrInfJTwmUGYgjLfHk8lqF072ND-FmLWEBnUTOpY8oJXp8FdWw2SalbdOeNlrtlJjwk4XK8Ql2iJ_2qMCtxsvLPhKBOqFoAF4aBvTOEDVJDxf0DaBSiydEEtfTVV2iwBcjWabu5J2XieR5y7QZQtuHsn7T3qKBvCcCejN3Y2oqAT3qMHvu1fTms1r_91wBn_K7Wjd9UkZ1n02qQcUHJznR_OF2BgN7_KWIDAF9ZS9keoju2NPpPelO4yxa2XUPnehY3G7dHKoCxUEQR4d2Xc5voqDASTVCDqQS4PVOZdvT3Ein6-SanAlCwbWBbkvT8g6-5PImQ

# Now load the JWS, validate, and recover the original text.
set jws2 [new_CkJws]

# Load the JWS.
set success [CkJws_LoadJws $jws2 $jwsCompact]

# rsaPubKey is a CkPublicKey
set rsaPubKey [CkPrivateKey_GetPublicKey $rsaKey]

# Set the RSA public key used for validation.
set signatureIndex 0
CkJws_SetPublicKey $jws2 $signatureIndex $rsaPubKey
delete_CkPublicKey $rsaPubKey

# Validate the 1st (and only) signature at index 0..
set v [CkJws_Validate $jws2 $signatureIndex]
if {$v < 0} then {
    # Perhaps Chilkat was not unlocked or the trial expired..
    puts "Method call failed for some other reason."
    puts [CkJws_lastErrorText $jws2]
    delete_CkStringBuilder $sbJwk
    delete_CkPrivateKey $rsaKey
    delete_CkJsonObject $jwsProtHdr
    delete_CkJws $jws
    delete_CkJws $jws2
    exit
}

if {$v == 0} then {
    puts "Invalid signature.  The RSA key was incorrect, the JWS was invalid, or both."
    delete_CkStringBuilder $sbJwk
    delete_CkPrivateKey $rsaKey
    delete_CkJsonObject $jwsProtHdr
    delete_CkJws $jws
    delete_CkJws $jws2
    exit
}

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

# Recover the original content:
puts [CkJws_getPayload $jws2 utf-8]

# Examine the protected header:
# joseHeader is a CkJsonObject
set joseHeader [CkJws_GetProtectedHeader $jws2 $signatureIndex]
if {[CkJws_get_LastMethodSuccess $jws2] != 1} then {
    puts "No protected header found at the given index."
    delete_CkStringBuilder $sbJwk
    delete_CkPrivateKey $rsaKey
    delete_CkJsonObject $jwsProtHdr
    delete_CkJws $jws
    delete_CkJws $jws2
    exit
}

CkJsonObject_put_EmitCompact $joseHeader 0

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

# Output:

# 	Signature validated.
# 	In our village, folks say God crumbles up the old moon into stars.
# 	Protected (JOSE) header:
# 	{ 
# 	  "alg": "PS256"
# 	}

delete_CkStringBuilder $sbJwk
delete_CkPrivateKey $rsaKey
delete_CkJsonObject $jwsProtHdr
delete_CkJws $jws
delete_CkJws $jws2