MIME S/MIME Encryption Algorithm Properties

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Demonstrates the properties that control S/MIME encryption: Pkcs7CryptAlg (the symmetric content-encryption algorithm), Pkcs7KeyLength (the content-encryption key length in bits), OaepPadding (whether RSAES-OAEP key transport is used instead of RSAES-PKCS1-v1_5), and the OAEP hash settings OaepHash and OaepMgfHash. The properties are configured before calling Encrypt.

#include <C_CkMime.h>
#include <C_CkCert.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkMime mime;
    HCkCert cert;

    success = FALSE;

    mime = CkMime_Create();
    success = CkMime_SetBodyFromPlainText(mime,"This message will be encrypted.");
    if (success == FALSE) {
        printf("%s\n",CkMime_lastErrorText(mime));
        CkMime_Dispose(mime);
        return;
    }

    //  Pkcs7CryptAlg is the symmetric content-encryption algorithm.  Supported values are aes, aes-gcm,
    //  des, 3des, and rc2.  The default is aes.
    CkMime_putPkcs7CryptAlg(mime,"aes");

    //  Pkcs7KeyLength is the content-encryption key length in bits.  The default is 128.
    CkMime_putPkcs7KeyLength(mime,256);

    //  OaepPadding selects the RSA key-transport padding.  The default is FALSE (RSAES-PKCS1-v1_5).
    //  Set TRUE to use RSAES-OAEP, in which case the OAEP hash settings apply.
    CkMime_putOaepPadding(mime,TRUE);
    CkMime_putOaepHash(mime,"sha256");
    CkMime_putOaepMgfHash(mime,"sha256");

    //  Load the recipient certificate (public key is sufficient for encrypting).
    cert = CkCert_Create();
    success = CkCert_LoadFromFile(cert,"qa_data/recipient.cer");
    if (success == FALSE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkMime_Dispose(mime);
        CkCert_Dispose(cert);
        return;
    }

    //  Encrypt using the algorithm settings configured above.
    success = CkMime_Encrypt(mime,cert);
    if (success == FALSE) {
        printf("%s\n",CkMime_lastErrorText(mime));
        CkMime_Dispose(mime);
        CkCert_Dispose(cert);
        return;
    }

    printf("Encrypted with %s %d-bit key.\n",CkMime_pkcs7CryptAlg(mime),CkMime_getPkcs7KeyLength(mime));


    CkMime_Dispose(mime);
    CkCert_Dispose(cert);

    }