(Objective-C) RSA Encrypt Hash using SHA256 hash function and SHA1 mask function

Note: This example requires a feature introduced in Chilkat v9.5.0.66

How can this Javascript be duplicated using Chilkat?

function a(e, t) {
                var r = s.pki.publicKeyFromPem(e)
                  , n = r.encrypt(t, "RSA-OAEP", {
                    md: s.md.sha256.create(),
                    mgf1: {
                        md: s.md.sha1.create()
                    }
                });
                return s.util.encode64(n)
            }

Note: The OAEP padding uses random bytes in the padding, and therefore each time encryption happens, even using the same data and key, the result will be different -- but still valid. One should not expect to get the same output.

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#import <CkoPublicKey.h>
#import <CkoStringBuilder.h>
#import <NSString.h>
#import <CkoCrypt2.h>
#import <CkoRsa.h>

// Note: This example requires a feature introduced in Chilkat v9.5.0.66

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

CkoPublicKey *pubkey = [[CkoPublicKey alloc] init];

CkoStringBuilder *sbPem = [[CkoStringBuilder alloc] init];
BOOL bCrlf = YES;
[sbPem AppendLine: @"-----BEGIN PUBLIC KEY-----" crlf: bCrlf];
[sbPem AppendLine: @"MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA33TqqLR3eeUmDtHS89qF" crlf: bCrlf];
[sbPem AppendLine: @"3p4MP7Wfqt2Zjj3lZjLjjCGDvwr9cJNlNDiuKboODgUiT4ZdPWbOiMAfDcDzlOxA" crlf: bCrlf];
[sbPem AppendLine: @"04DDnEFGAf+kDQiNSe2ZtqC7bnIc8+KSG/qOGQIVaay4Ucr6ovDkykO5Hxn7OU7s" crlf: bCrlf];
[sbPem AppendLine: @"Jp9TP9H0JH8zMQA6YzijYH9LsupTerrY3U6zyihVEDXXOv08vBHk50BMFJbE9iwF" crlf: bCrlf];
[sbPem AppendLine: @"wnxCsU5+UZUZYw87Uu0n4LPFS9BT8tUIvAfnRXIEWCha3KbFWmdZQZlyrFw0buUE" crlf: bCrlf];
[sbPem AppendLine: @"f0YN3/Q0auBkdbDR/ES2PbgKTJdkjc/rEeM0TxvOUf7HuUNOhrtAVEN1D5uuxE1W" crlf: bCrlf];
[sbPem AppendLine: @"SwIDAQAB" crlf: bCrlf];
[sbPem AppendLine: @"-----END PUBLIC KEY-----" crlf: bCrlf];

// Load the public key object from the PEM. 
BOOL success = [pubkey LoadFromString: [sbPem GetAsString]];
if (success != YES) {
    NSLog(@"%@",pubkey.LastErrorText);
    return;
}

NSString *originalData = @"This is the original data to be SHA-256 hashed and RSA encrypted.";

// First we SHA-256 hash the original data to get the hash in base64 format:
CkoCrypt2 *crypt = [[CkoCrypt2 alloc] init];
crypt.HashAlgorithm = @"SHA-256";
crypt.EncodingMode = @"base64";
NSString *hashBase64 = [crypt HashStringENC: originalData];

// Setup RSA to use OAEP padding with SHA-1 for the mask function.
CkoRsa *rsa = [[CkoRsa alloc] init];
rsa.OaepPadding = YES;
rsa.OaepHash = @"SHA1";
[rsa ImportPublicKeyObj: pubkey];
rsa.EncodingMode = @"base64";

// Starting in v9.5.0.66, we can provide a binary encoding mode, such as "base64", "hex", "base64url", etc.
// for the Charset property.   The Charset property was previously limited to character encodings, such as
// "utf-8", "iso-8859-1", etc.  If a binary encoding is used, then the string passed in is decoded to the binary
// bytes as indicated.  (If an actual charset, such as "utf-8" is used, then the input string is converted to the
// byte representation of the charset, and then encrypted.)

// Given that a hash is composed of non-text binary bytes, we'll set the Charset property equal to "base64" 
// (because we have the base64 hash from above).
rsa.Charset = @"base64";

// Note: The OAEP padding uses random bytes in the padding, and therefore each time encryption happens,
// even using the same data and key, the result will be different --  but still valid.  One should not expect
// to get the same output.
BOOL bUsePrivateKey = NO;
NSString *encryptedStr = [rsa EncryptStringENC: hashBase64 bUsePrivateKey: bUsePrivateKey];
if (rsa.LastMethodSuccess != YES) {
    NSLog(@"%@",rsa.LastErrorText);
    return;
}

NSLog(@"%@%@",@"Base64 RSA encrypted output: ",encryptedStr);