(C) RSASSA-PSS Algorithm with SHA256 Hashing

RSA encrypt a SHA256 hash with OAEP padding.

Note: This example requires Chilkat v11.0.0 or greater.

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#include <C_CkPrivateKey.h>
#include <C_CkRsa.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkPrivateKey privkey;
    HCkRsa rsa;
    const char *sigStr;

    success = FALSE;

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

    privkey = CkPrivateKey_Create();

    // Load the private key object from a PEM file.
    // (To load from a PEM string, call LoadPem instead.)
    success = CkPrivateKey_LoadPemFile(privkey,"somePath/myPrivateKey.pem");
    if (success == FALSE) {
        printf("%s\n",CkPrivateKey_lastErrorText(privkey));
        CkPrivateKey_Dispose(privkey);
        return;
    }

    rsa = CkRsa_Create();
    // Use RSA-PSS by setting PkcsPadding = FALSE
    CkRsa_putPkcsPadding(rsa,FALSE);
    // Use SHA256
    CkRsa_putOaepHash(rsa,"SHA-256");

    CkRsa_UsePrivateKey(rsa,privkey);

    // Generate a base64 signature.
    CkRsa_putEncodingMode(rsa,"base64");

    sigStr = CkRsa_signStringENC(rsa,"String to be signed","SHA-256");
    if (CkRsa_getLastMethodSuccess(rsa) == FALSE) {
        printf("%s\n",CkRsa_lastErrorText(rsa));
        CkPrivateKey_Dispose(privkey);
        CkRsa_Dispose(rsa);
        return;
    }

    printf("Signature: %s\n",sigStr);


    CkPrivateKey_Dispose(privkey);
    CkRsa_Dispose(rsa);

    }