CODEWITHSUNDEEP
c++encryptionrsablackberry-10
mariomunera
mariomunera

Reputation: 323

RSA encrypt for C++ (BB10)

Resolved (look for my answer). I need help encrypting a password with RSA in C++. I'm working for Blackberry10 in C++ and I've been looking for a RSA tutorial or something that walk me through the encrypting process but sadly I haven't found anything consistant.

I've been told that the process consist basicaly in three steps:

1)Generate the RSA public key with the module and exponent. 2)Encrypt the text with the public key. 3)Encrypt the text again in base640.

If you are wondering why I need to follow this three steps is because I'm working in a banking app, and those are their requirements.

I've been searching all over and I haven't found even how to make the first step, generate the public key with the module and the exponent (I already have both).

Any help will be appreciated.

Thanks.

Is not that I'm building the whole app by myself. We are a team and I need to encrypt just the client password with RSA and send it to the next step of the process. I do have experiencie working with Blackberry and RSA but in Java, where the process is a little bit easier, e.g: In java the first step once you got the module and public exponent is create the RSA Public Key Object through a very simple syntaxis: RSAPublicKey publicKey = new RSAPublicKey(new RSACryptoSystem(2048),ebytes, mbytes);. In this part is where I'm little bit lost because I haven't found the proper BB10 documentation. I'm sorry if I created the illusion that I'm creating a whole encryption API by myself. BB10 has this security API based in hursa.h (https://developer.blackberry.com/native/beta/reference/com.qnx.doc.crypto/topic/about_rsa_raw.html) I'm trying to implement it, but I haven't been successful. @owlstead @dajames @bta

Upvotes: 0

Views: 3049

Answers (3)

mariomunera
mariomunera

Reputation: 323

Resolved. After doing some research and getting to know better with BB10 coding and RSA, I finally came out with the solution to successfuly encrypt a plain text with RSA and Base64 in C/C++ for BB10 or any other platform. Please take in consideration that I have the modulus and the public exponent of the rsa object from the services that I'm working with.

The code:

    QByteArray answer;

    RSA* rsa = RSA_new();

    BIGNUM *modulus = BN_new();
    BIGNUM *exponent = BN_new();
    const char *modulusString = rsaObj->getM(); //My Modulus
    const char *exponentString = rsaObj->getE(); //My exponent

    BN_hex2bn(&modulus, modulusString);
    BN_hex2bn(&exponent, exponentString);

    rsa->n = BN_new();
    BN_copy(rsa->n, modulus);
    rsa->e = BN_new();
    BN_copy(rsa->e, exponent);

    int maxSize = RSA_size(rsa);
    qDebug() << "maxSize:" << maxSize;

    const char *inn = "1234";
    unsigned char *encrypted = (unsigned char*) malloc(maxSize);
    int bufferSize = RSA_public_encrypt(strlen(inn), (unsigned char *) inn,
            encrypted, rsa, RSA_PKCS1_PADDING);

    if (bufferSize == -1) {
        RSA_free(rsa);
        qDebug() << "Error";
    }

    QByteArray enc = QByteArray::fromRawData((const char*) encrypted, 256);
    answer = enc.toBase64();

    return answer;

Thanks and I expect this helps to the new BB10 developers

Upvotes: 0

dajames
dajames

Reputation: 2916

It seems to me that you know even less than you think you do about how this cryptography works.

One doesn't usually use RSA encryption to encrypt data. It can be done for something short like a PIN or password, but what is usually done is to generate a symmetric key and to encrypt the data with the symmetric key and then use RSA to encrypt the symmetric key.

If you are sending a password to a bank then what you are probably supposed to be doing is to use the RSA key supplied by the bank in their own key certificate. Only the bank has the private key, so only they can decrypt the password. If that's right then you don't need to generate an RSA key, but you do need to verify that the certificate is trusted.

I don't program Blackberries, so I don't know what cryptography APIs they support, but I would expect everything you need to be built-in. This is all pretty standard stuff.

I recommend that you start by reading up on public key cryptography (e.g. on Wikipedia here and here) before starting to design your solution.

Upvotes: 1

bta
bta

Reputation: 45077

I highly recommend that you take advantage of an existing encryption library to handle all of this for you. OpenSSL is widely used, and the LibTom libraries include an encryption lib as well. Encryption is not an easy thing to implement from scratch, and you will save a considerable amount of time and frustration by using an existing implementation. OpenSSL in particular is a good choice, as it has passed FIPS certification tests multiple times. Since you're working on a banking app, you (and your customers) will most likely want to use an implementation that has been certified.

Even if you insist on implementing your own encryption libraries from scratch, I encourage you to check out the aforementioned libraries as examples.

Upvotes: 3

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