Create CSR using PKCS10 and sign with RSA keys In Swift

Question

I generated RSA keys and my backend sends 3 parameters in BASE64 (except signatureAlgorithm) for creating CSR to me:

"subject" : "MIGfMQswCQYDVQQGEwJJUjEvMC0GA1UEAwwmMTAwMDAwMzg1MDA3NjAxMy3YqNmH2LLYp9ivINi12KfYr9mC24wxGTAXBgNVBAUTEDEwMDAwMDM4NTAwNzYwMTMxEzARBgNVBCoMCtio2YfYstin2K8xEzARBgNVBAQMCti12KfYr9mC24wxGjAYBgkqhkiG9w0BCQEWC2luZm9AdWlkLmly",
"extensions" : "MDMwDgYDVR0PAQH/BAQDAgXgMBYGA1UdJQEB/wQMMAoGCCsGAQUFBwMCMAkGA1UdEQQCMAA="
"signatureAlgorithm" : "SHA256_WITH_RSA"

I have sample code in Android/java using BouncyCastle to do this:

byte[] subjectBytes = EncodingUtils.decode(receivedSubject);
byte[] extensionsBytes = EncodingUtils.decode(receivedExtensions);

X500Name subject = X500Name.getInstance(ASN1Primitive.fromByteArray(subjectBytes));
Extensions extensions = Extensions.getInstance(ASN1Primitive.fromByteArray(extensionsBytes));

PKCS10CertificationRequestBuilder p10Builder = new JcaPKCS10CertificationRequestBuilder(subject, publicKey);

if (extensions != null)
    p10Builder.addAttribute(PKCSObjectIdentifiers.pkcs_9_at_extensionRequest, extensions);

ContentSigner signer = new ContentSigner() {

    final ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

    @Override
    public AlgorithmIdentifier getAlgorithmIdentifier() {
        return new DefaultSignatureAlgorithmIdentifierFinder()
                .find(receivedAlgorithm);
    }

    @Override
    public OutputStream getOutputStream() {
        return this.outputStream;
    }

    @Override
    public byte[] getSignature() {
        try {
            byte[] tbs = ((ByteArrayOutputStream) getOutputStream()).toByteArray();

            return SignatureHelper.sign(privateKey, tbs,
                    csrFormat.getSignatureProfile().getSignatureAlgorithm());
        } catch (NoSuchAlgorithmException | InvalidKeyException | SignatureException e) {
            throw new CsrGenerationException();
        }
    }
};

return p10Builder.build(signer).getEncoded();

How can I do the same in iOS with swift?

Is there any library to accept subject and extensions to create CSR and sign it?

there is a Apple library called `CryptoKit` that may be worth looking into. — workingdog support Ukraine, Nov 29 '21 at 08:45
what do you exactly need from this string..? do you need to save value..? do you need to do decryption or do something else. — Noor Ahmed Natali, Dec 01 '21 at 11:01
as I mentioned in title, I want to create CSR. and send back encoded version to server. — Mahdi Moqadasi, Dec 01 '21 at 11:07
Take a look into this library https://github.com/outfoxx/Shield. Here is mentioned PKCS10. — Ramis, Dec 02 '21 at 22:29
I checked it before, but its dependencies are not compiled as well and some subjects are different from BouncyCastle. I appreciate anybody can match classes with my case, as exists in the android sample code above. — Mahdi Moqadasi, Dec 04 '21 at 14:15
Not pretty, but consider [using a Java bridge](https://github.com/SwiftJava/SwiftJava) — henry700, Dec 04 '21 at 16:33
I think with a few modifications you can use this https://github.com/ateska/ios-csr — Christos Koninis, Dec 06 '21 at 07:12

Create CSR using PKCS10 and sign with RSA keys In Swift

0 Answers0