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(Visual FoxPro) Compress and Encrypt a Large File (Low and Constant Memory Footprint)See more Compression ExamplesDemonstrates how to compress and encrypt a large file such that the memory footprint remains low and constant. Note: This example requires Chilkat v9.5.0.99 or greater.
LOCAL loCompress LOCAL lnSuccess LOCAL loJson LOCAL lcInPath LOCAL lcOutPath LOCAL lcInPath2 LOCAL lcOutPath2 LOCAL loCrypt LOCAL lcDecryptedPath LOCAL lcOutPath3 * This example assumes the Chilkat API to have been previously unlocked. * See Global Unlock Sample for sample code. loCompress = CreateObject('Chilkat_9_5_0.Compression') loCompress.Algorithm = "deflate" * Set encryption params. * The possible values are the same as for the corresponding properties in the Chilkat Crypt2 class/object. * The encoded IV and Key must be specified as hex. loJson = CreateObject('Chilkat_9_5_0.JsonObject') loJson.UpdateString("cryptAlgorithm","aes") loJson.UpdateString("cipherMode","cbc") loJson.UpdateInt("keyLength",128) loJson.UpdateInt("paddingScheme",0) loJson.UpdateString("encodedIV","000102030405060708090A0B0C0D0E0F") loJson.UpdateString("encodedKey","000102030405060708090A0B0C0D0E0F") * Do file-to-file compression+encryption in a single call. lcInPath = "qa_data/largeFile.dat" lcOutPath = "c:/temp/qa_output/compressed_encrypted.dat" lnSuccess = loCompress.CompressEncryptFile(loJson,lcInPath,lcOutPath) IF (lnSuccess = 0) THEN ? loCompress.LastErrorText RELEASE loCompress RELEASE loJson CANCEL ENDIF * We can do file-to-file decrypt/decompress like this: lcInPath2 = lcOutPath lcOutPath2 = "c:/temp/qa_output/restored.dat" lnSuccess = loCompress.DecryptDecompressFile(loJson,lcInPath2,lcOutPath2) IF (lnSuccess = 0) THEN ? loCompress.LastErrorText RELEASE loCompress RELEASE loJson CANCEL ENDIF * Note: The above decrypt + decompress is the equivalent of doing the same in these two steps: loCrypt = CreateObject('Chilkat_9_5_0.Crypt2') loCrypt.CryptAlgorithm = "aes" loCrypt.CipherMode = "cbc" loCrypt.KeyLength = 128 loCrypt.PaddingScheme = 0 loCrypt.SetEncodedIV("000102030405060708090A0B0C0D0E0F","hex") loCrypt.SetEncodedKey("000102030405060708090A0B0C0D0E0F","hex") lcDecryptedPath = "c:/temp/qa_output/decrypted.dat" lnSuccess = loCrypt.CkDecryptFile(lcInPath2,lcDecryptedPath) IF (lnSuccess = 0) THEN ? loCrypt.LastErrorText RELEASE loCompress RELEASE loJson RELEASE loCrypt CANCEL ENDIF lcOutPath3 = "c:/temp/qa_output/restored_in_two_steps.dat" lnSuccess = loCompress.DecompressFile(lcDecryptedPath,lcOutPath3) IF (lnSuccess = 0) THEN ? loCompress.LastErrorText RELEASE loCompress RELEASE loJson RELEASE loCrypt CANCEL ENDIF ? "Success." RELEASE loCompress RELEASE loJson RELEASE loCrypt |
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