(MFC) openssl enc decrypt

Demonstrates how to decrypt a file that was encrypted using "openssl enc".

This example shows how to decrypt what was created using this openssl command:

openssl enc -e -aes-256-cbc -in hamlet.xml -out hamlet.enc -pass file:./secret.txt

This example shows how to do this:

openssl enc -d -aes-256-cbc -in hamlet.enc -out hamlet_dec.xml -pass file:./secret.txt

Note: This example requires Chilkat v9.5.0.71 or later.

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

See Also: Using MFC CString in Chilkat

#include <CkCrypt2.h>
#include <CkBinData.h>

void ChilkatSample(void)
    {
    CkString strOut;

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

    CkCrypt2 crypt;

    // Use aes-256-cbc
    crypt.put_CryptAlgorithm("aes");
    crypt.put_CipherMode("cbc");
    crypt.put_KeyLength(256);

    // We'll need to set the hash algorithm to either MD5 or SHA256.
    // openssl version 1.0.* or earlier used MD5 by default
    // openssl version 1.1.* uses SHA-256 for the password to secret key derivation.

    // For example, if openssl 1.1.0 was used, we should do this:
    crypt.put_HashAlgorithm("sha256");

    // This example assumes openssl 1.0.2 was used to encrypt what we're now decrypting:
    crypt.put_HashAlgorithm("md5");

    // The openssl command we are duplicating is:
    // 
    //    openssl enc -d -aes-256-cbc -in hamlet.enc -out hamlet_dec.xml -pass file:./secret.txt
    // 
    // The file secret.txt contains the word "secret".  We could write code to load the contents
    // of secret.txt, but instead we'll just do this:
    crypt.SetSecretKeyViaPassword("secret");

    // Load the file to be decrypted.
    CkBinData fileData;
    bool success = fileData.LoadFile("qa_data/openssl_enc/hamlet.enc");

    // Decrypt
    success = crypt.DecryptBd(fileData);

    // Save the decrypted output.
    success = fileData.WriteFile("qa_output/hamlet_dec.xml");

    strOut.append("success = ");
    strOut.appendInt(success);
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }