Decrypt Method

Decrypts the data.

Syntax

• C++
• Objective-C
• C

ANSI (Cross Platform)
int Decrypt();

Unicode (Windows)
INT Decrypt();

- (void)decrypt;

#define MID_SALSA20_DECRYPT 3

IPWORKSENCRYPT_EXTERNAL int IPWORKSENCRYPT_CALL IPWorksEncrypt_Salsa20_Do(void *lpObj, int methid, int cparam, void *param[], int cbparam[], int64 *lpllVal);

Remarks

Decrypt will decrypt the specified data. The following properties are applicable:

• IV (required)
• Key (required)

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• SetInputStream
• InputFile
• InputMessage

When a valid source is found the search stops. The order in which the output properties are checked is as follows:

• SetOutputStream
• OutputFile
• OutputMessage: The output data is written to this property if no other destination is specified.

When using streams you may need to additionally set CloseInputStreamAfterProcessing or CloseOutputStreamAfterProcessing.

Additional Notes

The Key property must be set to the 256 bit (32 byte) value originally used to encrypt the data. IV must be set to the original IV value used to encrypt the data.

If using a password, KeyPassword must be set to the same KeyPassword used when encrypting the data. This will automatically generate both Key and IV when Decrypt is called.

During decryption the Progress event will fire as data is decrypted.

Decrypt Example

Salsa20 salsa = new Salsa20();

//32 Bytes
salsa.KeyB = new byte[] { 0xBB, 0x76, 0x17, 0xC9, 0x05, 0x73, 0x4A, 0x8D, 0x59, 0x9D, 0x7B, 0x0D, 0x86, 0x2A, 0x03, 0x82, 0x50, 0x6A, 0x70, 0xFB, 0xA8, 0x56, 0x47, 0x1B, 0x1E, 0x68, 0x0B, 0x2B, 0x34, 0x18, 0x0F, 0xE2 };

//24 Bytes
salsa.IVB = new byte[] { 0x0D, 0xE4, 0x43, 0x40, 0x29, 0xAD, 0x70, 0x7D, 0x7B, 0x32, 0xB5, 0xC7, 0x0D, 0xE4, 0x43, 0x40, 0x29, 0xAD, 0x70, 0x7D, 0x7B, 0x32, 0xB5, 0xC7 };

salsa.InputMessageB = new byte[] { 0x06, 0xF4, 0xD9, 0xB4, 0x67, 0x31, 0x1C, 0x1E, 0x8E, 0xD6, 0xB5, 0x6B };
salsa.Decrypt();

Console.WriteLine(salsa.OutputMessage); //outputs "hello salsa!"

Error Handling (C++)

This method returns a result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message. (Note: This method's result code can also be obtained by calling the GetLastErrorCode() method after it returns.)