Swift

Verify an RSA Signature Against the Signed Hash

See more Apple Keychain Examples

Demonstrates how to validate an RSA Signature against the hash that was signed. Swift

func chilkatTest() {
    var success: Bool = false

    let bd = CkoBinData()!
    var i: Int
    for i = 0; i <= 100; i++ {
        bd.appendEncoded(encData: "000102030405060708090A0B0C0D0E0F", encoding: "hex")
    }

    var sha256_base64: String? = bd.getHash(algorithm: "sha256", encoding: "base64")
    print("sha256 hash in base64 format: \(sha256_base64!)")

    var base64_rsa_sig: String? = "AwF2BbOvL6jA5DwmMAc9n6J2Cc8PI6Rj5W079+aKJcIEtPWRzHor0Bvc3aftGM3Jbgj6SXlIC3M3RYS7UZOnfiHKFNZgbxaNT5WwsWooK42ZkC8DBZl0p7OunBUKd5SciUo+TKilioeUkriN3L1Zl9hwi3HVDVqgVo3XXskwIftSqLSFlepTLTmOWj9Y93dp8J4D9RyLtNgFQBc0WB22tyJTsuY56mLcWe1AMF3LizB9OrbwjynF2u16xWlrJdugccz795fJBUV9aQSD+8S3KeqwQhoi8RK1uhD68aGCyaSpBq0NZ8COAkn7MXaF4POxrAAt8udfHM+PRfSOptcH/w=="

    // Get the public key to be used for signature verification.
    let pubKey = CkoPublicKey()!
    success = pubKey.load(fromFile: "rsaKeys/chilkat-rsa-2048.pem")
    if success == false {
        print("\(pubKey.lastErrorText!)")
        return
    }

    let rsa = CkoRsa()!
    success = rsa.usePublicKey(pubKey: pubKey)
    if success == false {
        print("\(rsa.lastErrorText!)")
        return
    }

    // Verify the hash against the signature.
    rsa.encodingMode = "base64"
    success = rsa.verifyHashENC(encodedHash: sha256_base64, hashAlg: "sha256", encodedSig: base64_rsa_sig)

    if success == false {
        print("\(rsa.lastErrorText!)")
        print("Signature invalid.")
    }
    else {
        print("Signature valid.")
    }


}