Visual FoxPro

Example: Hash Text in Chunks

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

LOCAL lnSuccess
LOCAL loCrypt
LOCAL loBd
LOCAL s
LOCAL i
LOCAL lcEncodedHash

lnSuccess = 0

loCrypt = CreateObject('Chilkat.Crypt2')
loCrypt.HashAlgorithm = "sha256"
loCrypt.Charset = "utf-8"

loBd = CreateObject('Chilkat.BinData')

s = "The quick brown fox jumped over the lazy dog." + CHR(13) + CHR(10)

* 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.

loBd.AppendString(s,"utf-8")
lnSuccess = loCrypt.HashBeginString(s)

i = 0
DO WHILE i < 200
    loBd.AppendString(s,"utf-8")
    loCrypt.HashMoreString(s)
    i = i + 1
ENDDO

* Get the hash in base64 format.
loCrypt.EncodingMode = "base64"

lcEncodedHash = loCrypt.HashFinalENC()
? "Hash computed in chunks: " + lcEncodedHash

* Let's alternatively compute the hash of the entire amount of data at once,
* to show the hash computation is the same:
lcEncodedHash = loCrypt.HashBdENC(loBd)
? "Hash computed in 1 step: " + lcEncodedHash

* Output:

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

RELEASE loCrypt
RELEASE loBd