(C) 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.

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#include <C_CkCrypt2.h>
#include <C_CkBinData.h>

void ChilkatSample(void)
    {
    HCkCrypt2 crypt;
    HCkBinData fileData;
    BOOL success;

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

    crypt = CkCrypt2_Create();

    // Use aes-256-cbc
    CkCrypt2_putCryptAlgorithm(crypt,"aes");
    CkCrypt2_putCipherMode(crypt,"cbc");
    CkCrypt2_putKeyLength(crypt,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:
    CkCrypt2_putHashAlgorithm(crypt,"sha256");

    // This example assumes openssl 1.0.2 was used to encrypt what we're now decrypting:
    CkCrypt2_putHashAlgorithm(crypt,"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:
    CkCrypt2_SetSecretKeyViaPassword(crypt,"secret");

    // Load the file to be decrypted.
    fileData = CkBinData_Create();
    success = CkBinData_LoadFile(fileData,"qa_data/openssl_enc/hamlet.enc");

    // Decrypt
    success = CkCrypt2_DecryptBd(crypt,fileData);

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

    printf("success = %d\n",success);


    CkCrypt2_Dispose(crypt);
    CkBinData_Dispose(fileData);

    }