(Swift 2) 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.

Chilkat Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

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

    let rsaKey = CkoPrivateKey()
    // 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..)
    var success: Bool = rsaKey.LoadJwk(sbJwk.GetAsString())
    if success != true {
        print("\(rsaKey.LastErrorText)")
        return
    }

    // Create the JWS Protected Header
    let jwsProtHdr = CkoJsonObject()
    jwsProtHdr.AppendString("alg", value: "PS256")

    let jws = CkoJws()

    // Set the protected header:
    var signatureIndex: Int = 0
    jws.SetProtectedHeader(signatureIndex, json: jwsProtHdr)

    // Set the RSA key:
    jws.SetPrivateKey(signatureIndex, privKey: rsaKey)

    // Set the payload.
    var bIncludeBom: Bool = false
    var payloadStr: String? = "In our village, folks say God crumbles up the old moon into stars."
    jws.SetPayload(payloadStr, charset: "utf-8", includeBom: bIncludeBom)

    // Create the JWS
    // By default, the compact serialization is used.
    var jwsCompact: String? = jws.CreateJws()
    if jws.LastMethodSuccess != true {
        print("\(jws.LastErrorText)")
        return
    }

    print("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.
    let jws2 = CkoJws()

    // Load the JWS.
    success = jws2.LoadJws(jwsCompact)

    var rsaPubKey: CkoPublicKey? = rsaKey.GetPublicKey()

    // Set the RSA public key used for validation.
    signatureIndex = 0
    jws2.SetPublicKey(signatureIndex, pubKey: rsaPubKey)
    rsaPubKey = nil

    // Validate the 1st (and only) signature at index 0..
    var v: Int = jws2.Validate(signatureIndex).intValue
    if v < 0 {
        // Perhaps Chilkat was not unlocked or the trial expired..
        print("Method call failed for some other reason.")
        print("\(jws2.LastErrorText)")
        return
    }

    if v == 0 {
        print("Invalid signature.  The RSA key was incorrect, the JWS was invalid, or both.")
        return
    }

    // If we get here, the signature was validated..
    print("Signature validated.")

    // Recover the original content:
    print("\(jws2.GetPayload("utf-8"))")

    // Examine the protected header:
    var joseHeader: CkoJsonObject? = jws2.GetProtectedHeader(signatureIndex)
    if jws2.LastMethodSuccess != true {
        print("No protected header found at the given index.")
        return
    }

    joseHeader.EmitCompact = false

    print("Protected (JOSE) header:")
    print("\(joseHeader!.Emit())")
    joseHeader = nil

    // Output:

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

}