Swift

Compress and Encrypt a Large File (Low and Constant Memory Footprint)

See more Compression Examples

Demonstrates 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.

Swift

func chilkatTest() {
    var success: Bool = false

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    let compress = CkoCompression()!
    compress.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.
    let json = CkoJsonObject()!
    json.updateString(jsonPath: "cryptAlgorithm", value: "aes")
    json.updateString(jsonPath: "cipherMode", value: "cbc")
    json.updateInt(jsonPath: "keyLength", value: 128)
    json.updateInt(jsonPath: "paddingScheme", value: 0)
    json.updateString(jsonPath: "encodedIV", value: "000102030405060708090A0B0C0D0E0F")
    json.updateString(jsonPath: "encodedKey", value: "000102030405060708090A0B0C0D0E0F")

    // Do file-to-file compression+encryption in a single call.
    var inPath: String? = "qa_data/largeFile.dat"
    var outPath: String? = "c:/temp/qa_output/compressed_encrypted.dat"
    success = compress.compressEncryptFile(cryptParams: json, srcPath: inPath, destPath: outPath)
    if success == false {
        print("\(compress.lastErrorText!)")
        return
    }

    // We can do file-to-file decrypt/decompress like this:
    var inPath2: String? = outPath
    var outPath2: String? = "c:/temp/qa_output/restored.dat"
    success = compress.decryptDecompressFile(cryptParams: json, srcPath: inPath2, destPath: outPath2)
    if success == false {
        print("\(compress.lastErrorText!)")
        return
    }

    // Note: The above decrypt + decompress is the equivalent of doing the same in these two steps:
    let crypt = CkoCrypt2()!
    crypt.cryptAlgorithm = "aes"
    crypt.cipherMode = "cbc"
    crypt.keyLength = 128
    crypt.paddingScheme = 0
    crypt.setEncodedIV(ivStr: "000102030405060708090A0B0C0D0E0F", encoding: "hex")
    crypt.setEncodedKey(keyStr: "000102030405060708090A0B0C0D0E0F", encoding: "hex")

    var decryptedPath: String? = "c:/temp/qa_output/decrypted.dat"
    success = crypt.ckDecryptFile(srcFile: inPath2, destFile: decryptedPath)
    if success == false {
        print("\(crypt.lastErrorText!)")
        return
    }

    var outPath3: String? = "c:/temp/qa_output/restored_in_two_steps.dat"
    success = compress.decompressFile(srcPath: decryptedPath, destPath: outPath3)
    if success == false {
        print("\(compress.lastErrorText!)")
        return
    }

    print("Success.")

}