(MFC) 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.

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkPublicKey.h>
#include <CkStringBuilder.h>
#include <CkCrypt2.h>
#include <CkRsa.h>

void ChilkatSample(void)
    {
    CkString strOut;

    // 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.

    CkPublicKey pubkey;

    CkStringBuilder sbPem;
    bool bCrlf = true;
    sbPem.AppendLine("-----BEGIN PUBLIC KEY-----",bCrlf);
    sbPem.AppendLine("MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA33TqqLR3eeUmDtHS89qF",bCrlf);
    sbPem.AppendLine("3p4MP7Wfqt2Zjj3lZjLjjCGDvwr9cJNlNDiuKboODgUiT4ZdPWbOiMAfDcDzlOxA",bCrlf);
    sbPem.AppendLine("04DDnEFGAf+kDQiNSe2ZtqC7bnIc8+KSG/qOGQIVaay4Ucr6ovDkykO5Hxn7OU7s",bCrlf);
    sbPem.AppendLine("Jp9TP9H0JH8zMQA6YzijYH9LsupTerrY3U6zyihVEDXXOv08vBHk50BMFJbE9iwF",bCrlf);
    sbPem.AppendLine("wnxCsU5+UZUZYw87Uu0n4LPFS9BT8tUIvAfnRXIEWCha3KbFWmdZQZlyrFw0buUE",bCrlf);
    sbPem.AppendLine("f0YN3/Q0auBkdbDR/ES2PbgKTJdkjc/rEeM0TxvOUf7HuUNOhrtAVEN1D5uuxE1W",bCrlf);
    sbPem.AppendLine("SwIDAQAB",bCrlf);
    sbPem.AppendLine("-----END PUBLIC KEY-----",bCrlf);

    // Load the public key object from the PEM. 
    bool success = pubkey.LoadFromString(sbPem.getAsString());
    if (success != true) {
        strOut.append(pubkey.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    const char *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:
    CkCrypt2 crypt;
    crypt.put_HashAlgorithm("SHA-256");
    crypt.put_EncodingMode("base64");
    const char *hashBase64 = crypt.hashStringENC(originalData);

    // Setup RSA to use OAEP padding with SHA-1 for the mask function.
    CkRsa rsa;
    rsa.put_OaepPadding(true);
    rsa.put_OaepHash("SHA1");
    rsa.ImportPublicKeyObj(pubkey);
    rsa.put_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.put_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 = false;
    const char *encryptedStr = rsa.encryptStringENC(hashBase64,bUsePrivateKey);
    if (rsa.get_LastMethodSuccess() != true) {
        strOut.append(rsa.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    strOut.append("Base64 RSA encrypted output: ");
    strOut.append(encryptedStr);
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }