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

void ChilkatSample(void)
    {
    HCkCrypt2 crypt;
    HCkBinData bd;
    const char *s;
    BOOL success;
    int i;
    const char *encodedHash;

    crypt = CkCrypt2_Create();
    CkCrypt2_putHashAlgorithm(crypt,"sha256");
    CkCrypt2_putCharset(crypt,"utf-8");

    bd = CkBinData_Create();

    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.

    CkBinData_AppendString(bd,s,"utf-8");
    success = CkCrypt2_HashBeginString(crypt,s);

    i = 0;
    while (i < 200) {
        CkBinData_AppendString(bd,s,"utf-8");
        CkCrypt2_HashMoreString(crypt,s);
        i = i + 1;
    }

    // Get the hash in base64 format.
    CkCrypt2_putEncodingMode(crypt,"base64");

    encodedHash = CkCrypt2_hashFinalENC(crypt);
    printf("Hash computed in chunks: %s\n",encodedHash);

    // Let's alternatively compute the hash of the entire amount of data at once,
    // to show the hash computation is the same:
    encodedHash = CkCrypt2_hashBdENC(crypt,bd);
    printf("Hash computed in 1 step: %s\n",encodedHash);

    // Output:

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


    CkCrypt2_Dispose(crypt);
    CkBinData_Dispose(bd);

    }