Lianja

Example: Hash Text in Chunks

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

llSuccess = .F.

loCrypt = createobject("CkCrypt2")
loCrypt.HashAlgorithm = "sha256"
loCrypt.Charset = "utf-8"

loBd = createobject("CkBinData")

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")
llSuccess = 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