DecryptBlock Method

Decrypts a block and returns the decrypted data.

Syntax

• C++
• Objective-C
• C

ANSI (Cross Platform)
char* DecryptBlock(const char* lpInputBuffer, int lenInputBuffer, int *lpSize = NULL);

Unicode (Windows)
LPSTR DecryptBlock(LPCSTR lpInputBuffer, INT lenInputBuffer, LPINT lpSize = NULL);

- (NSData*)decryptBlock:(NSData*)inputBuffer;

#define MID_SALSA20_DECRYPTBLOCK 4

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

Remarks

DecryptBlock will decrypt the input data and return the decrypted block. The decrypted block will always be the same length as the encrypted data. The following properties are applicable:

• IV (required)
• Key (required)

InputBuffer specifies the input data to decrypt.

DecryptBlock 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 };

byte[] tempDecryptedBlock;
 
//Decrypt any number of blocks of any size
tempDecryptedBlock = salsa.DecryptBlock(part1);
tempDecryptedBlock = salsa.DecryptBlock(part2);

Error Handling (C++)

This method returns a Binary String value (with length lpSize); after it returns, call the GetLastErrorCode() method to obtain its 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.