Create SecKey modulo and exponentially in fast

Question

I am trying to make my own SecKey using

exponent: let exponent = "10001" modulus: let modulus = "D6250B831F82EC984513922E797283E4D3879E1F0AD52364EBDA5A5696F6E75CDCE0704A993F3F95AA557A6882A525EC4B8344DA3E7DFDECCBACCEF18131E461D3C5D3D7E1334C6AE27E5CDEF8A577857542BCBEF6CF021B0EE5604534E6C6CBAEFA6EFFC1AB93DEE7CE51A8C8F2B7345680BDF840841C3A6F654CD1F10BA2FD5CA1C6E782A8FAEC79BD22FA12116D75FFAEDB2DEC151E0B60DB91F2E74BA78EFBB45DF739AF9CDD41C482DC22FC76E03C8E2141BDAE5406C0DA230E2C7EFFC68C8811E1544496332B03BCFF0F627A8DF51D2E2B32B0771D1C6F87AD56010DCB7A3862C63B88B2CF7D7AD40CC53AF0CFEC0820777C9CCE95A58848D67779AE8D" 

like publicKey for encrypting text in Swift. Can anybody help me?

Here is my code:

 import Foundation import Security class Encryption { var publicKeyPtr, privateKeyPtr: Unmanaged<SecKey>? var publicKey, privateKey: SecKey? let parameters: [String:String] = [kSecAttrKeyType: kSecAttrKeyTypeRSA, kSecAttrKeySizeInBits: "2048"] init(){ } func genKey() { let status = SecKeyGeneratePair(parameters, &publicKeyPtr, &privateKeyPtr) publicKey = publicKeyPtr!.takeRetainedValue() privateKey = privateKeyPtr!.takeRetainedValue() } func encrypt(plainText: String, publicKey: SecKey) -> [UInt8]{ let blockSize = SecKeyGetBlockSize(publicKey) let plainTextData = [UInt8](plainText.utf8) let plainTextDataLength = UInt(countElements( plainText)) var encryptedData = [UInt8](count: Int(blockSize), repeatedValue: 0) var encryptedDataLength = blockSize let result = SecKeyEncrypt(publicKey, SecPadding(kSecPaddingPKCS1), plainTextData, plainTextDataLength, &encryptedData, &encryptedDataLength) return encryptedData } func decrypt(data: [UInt8]) -> String{ let blockSize = SecKeyGetBlockSize(publicKey) var decryptedData = [UInt8](count: Int(blockSize), repeatedValue: 0) var decryptedDataLength = blockSize let result = SecKeyDecrypt(privateKey, SecPadding(kSecPaddingPKCS1), data, blockSize, &decryptedData, &decryptedDataLength) let decryptedText = String(bytes: decryptedData, encoding:NSUTF8StringEncoding) return decryptedText! } 

}