C Requires Chilkat v11.7.0+
C
Choose the PDF Encryption Algorithm: AES-256, AES-128 or RC4
See more PDF Protection Examples
Demonstrates the algorithmChoice option of the encrypt operation. aes-256 is the default and the one to use unless an older reader must open the file. aes-128 is for readers that predate AES-256. rc4-128 and rc4-40 are broken ciphers kept only for very old readers. Each algorithm needs a minimum PDF version, and the file header is raised to it when the PDF is saved, never lowered. A PDF saved with RC4 is written with a classic cross-reference table so that those old readers can parse it.Chilkat C Downloads
#include <C_CkJsonObject.h>
#include <C_CkPdf.h>
void ChilkatSample(void)
{
BOOL success;
HCkJsonObject json;
HCkJsonObject jsonOut;
HCkJsonObject info;
HCkPdf pdf1;
HCkPdf pdf2;
HCkPdf pdf3;
success = FALSE;
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.
// The PDF used in this example is available at two_page_memo.pdf
json = CkJsonObject_Create();
jsonOut = CkJsonObject_Create();
info = CkJsonObject_Create();
// AES-256, the default. Saved as PDF 1.7 with Adobe extension level 8.
pdf1 = CkPdf_Create();
success = CkPdf_LoadFile(pdf1,"qa_data/pdf/two_page_memo.pdf");
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf1));
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);
CkJsonObject_Dispose(info);
CkPdf_Dispose(pdf1);
return;
}
CkPdf_putUserPassword(pdf1,"user-secret");
CkPdf_putOwnerPassword(pdf1,"owner-secret");
CkJsonObject_UpdateString(json,"algorithmChoice","aes-256");
success = CkPdf_Protection(pdf1,"encrypt",json,jsonOut);
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf1));
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);
CkJsonObject_Dispose(info);
CkPdf_Dispose(pdf1);
return;
}
printf("aes-256 will be saved as PDF %s, Adobe extension level %d\n",CkJsonObject_stringOf(jsonOut,"pending.pdfVersion"),CkJsonObject_IntOf(jsonOut,"pending.adobeExtensionLevel"));
success = CkPdf_WriteFile(pdf1,"qa_output/memo_aes256.pdf");
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf1));
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);
CkJsonObject_Dispose(info);
CkPdf_Dispose(pdf1);
return;
}
success = CkPdf_PreLoadCheck(pdf1,"qa_output/memo_aes256.pdf",info);
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf1));
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);
CkJsonObject_Dispose(info);
CkPdf_Dispose(pdf1);
return;
}
printf(" saved file: %s, PDF %s\n",CkJsonObject_stringOf(info,"algorithm"),CkJsonObject_stringOf(info,"pdfVersion"));
// AES-128, for readers that predate AES-256. Saved as PDF 1.6.
pdf2 = CkPdf_Create();
success = CkPdf_LoadFile(pdf2,"qa_data/pdf/two_page_memo.pdf");
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf2));
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);
CkJsonObject_Dispose(info);
CkPdf_Dispose(pdf1);
CkPdf_Dispose(pdf2);
return;
}
CkPdf_putUserPassword(pdf2,"user-secret");
CkPdf_putOwnerPassword(pdf2,"owner-secret");
CkJsonObject_UpdateString(json,"algorithmChoice","aes-128");
success = CkPdf_Protection(pdf2,"encrypt",json,jsonOut);
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf2));
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);
CkJsonObject_Dispose(info);
CkPdf_Dispose(pdf1);
CkPdf_Dispose(pdf2);
return;
}
printf("aes-128 will be saved as PDF %s\n",CkJsonObject_stringOf(jsonOut,"pending.pdfVersion"));
success = CkPdf_WriteFile(pdf2,"qa_output/memo_aes128.pdf");
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf2));
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);
CkJsonObject_Dispose(info);
CkPdf_Dispose(pdf1);
CkPdf_Dispose(pdf2);
return;
}
success = CkPdf_PreLoadCheck(pdf2,"qa_output/memo_aes128.pdf",info);
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf2));
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);
CkJsonObject_Dispose(info);
CkPdf_Dispose(pdf1);
CkPdf_Dispose(pdf2);
return;
}
printf(" saved file: %s, PDF %s\n",CkJsonObject_stringOf(info,"algorithm"),CkJsonObject_stringOf(info,"pdfVersion"));
// RC4-128, a broken cipher, only for readers too old for AES. Saved as PDF 1.4.
pdf3 = CkPdf_Create();
success = CkPdf_LoadFile(pdf3,"qa_data/pdf/two_page_memo.pdf");
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf3));
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);
CkJsonObject_Dispose(info);
CkPdf_Dispose(pdf1);
CkPdf_Dispose(pdf2);
CkPdf_Dispose(pdf3);
return;
}
CkPdf_putUserPassword(pdf3,"user-secret");
CkPdf_putOwnerPassword(pdf3,"owner-secret");
CkJsonObject_UpdateString(json,"algorithmChoice","rc4-128");
success = CkPdf_Protection(pdf3,"encrypt",json,jsonOut);
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf3));
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);
CkJsonObject_Dispose(info);
CkPdf_Dispose(pdf1);
CkPdf_Dispose(pdf2);
CkPdf_Dispose(pdf3);
return;
}
printf("rc4-128 will be saved as PDF %s\n",CkJsonObject_stringOf(jsonOut,"pending.pdfVersion"));
success = CkPdf_WriteFile(pdf3,"qa_output/memo_rc4_128.pdf");
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf3));
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);
CkJsonObject_Dispose(info);
CkPdf_Dispose(pdf1);
CkPdf_Dispose(pdf2);
CkPdf_Dispose(pdf3);
return;
}
success = CkPdf_PreLoadCheck(pdf3,"qa_output/memo_rc4_128.pdf",info);
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf3));
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);
CkJsonObject_Dispose(info);
CkPdf_Dispose(pdf1);
CkPdf_Dispose(pdf2);
CkPdf_Dispose(pdf3);
return;
}
printf(" saved file: %s, PDF %s\n",CkJsonObject_stringOf(info,"algorithm"),CkJsonObject_stringOf(info,"pdfVersion"));
// Sample output:
// aes-256 will be saved as PDF 1.7, Adobe extension level 8
// saved file: aes-256, PDF 1.7
// aes-128 will be saved as PDF 1.6
// saved file: aes-128, PDF 1.6
// rc4-128 will be saved as PDF 1.4
// saved file: rc4-128, PDF 1.4
CkJsonObject_Dispose(json);
CkJsonObject_Dispose(jsonOut);
CkJsonObject_Dispose(info);
CkPdf_Dispose(pdf1);
CkPdf_Dispose(pdf2);
CkPdf_Dispose(pdf3);
}