(C++) Example: Hash Text in Chunks

Shows how to generate a final hash, like SHA-256, for a large text by processing it in chunks.

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

void ChilkatSample(void)
    {
    CkCrypt2 crypt;
    crypt.put_HashAlgorithm("sha256");
    crypt.put_Charset("utf-8");

    CkBinData bd;

    const char *s = "The quick brown fox jumped over the lazy dog.\r\n";

    // Accumulate the text in a StringBuilder.  We'll demonstrate hashing the text in chunks,
    // and then also hashing the entire text at once to show the results are the same.

    bd.AppendString(s,"utf-8");
    bool success = crypt.HashBeginString(s);

    int i = 0;
    while (i < 200) {
        bd.AppendString(s,"utf-8");
        crypt.HashMoreString(s);
        i = i + 1;
    }

    // Get the hash in base64 format.
    crypt.put_EncodingMode("base64");

    const char *encodedHash = crypt.hashFinalENC();
    std::cout << "Hash computed in chunks: " << encodedHash << "\r\n";

    // Let's alternatively compute the hash of the entire amount of data at once,
    // to show the hash computation is the same:
    encodedHash = crypt.hashBdENC(bd);
    std::cout << "Hash computed in 1 step: " << encodedHash << "\r\n";

    // Output:

    // Hash computed in chunks: unwkVff61k40roRIJizaknreScHaL6frWe37kydXbZQ=
    // Hash computed in 1 step: unwkVff61k40roRIJizaknreScHaL6frWe37kydXbZQ=
    }