TDESDecryptCTR

Decrypts a variable length data stream in the CTR mode.

Syntax

IppStatus ippsTDESDecryptCTR(const Ipp8u *pSrc, Ipp8u *pDst, int srcLen, const IppsDESSpec *pCtx1, const IppsDESSpec *pCtx2, const IppsDESSpec *pCtx3, Ipp8u *pCtrValue, int ctrNumBitSize);

Parameters

pSrc	Input ciphertext data stream of a variable length.
pDst	Resulting plaintext data stream.
srcLen	Length of the plaintext data stream in bytes.
pCtx1	First set of round keys scheduled for TDES internal operations.
pCtx2	Second set of round keys scheduled for TDES internal operations.
pCtx3	Third set of round keys scheduled for TDES internal operations.
pCtrValue	Counter.
ctrNumBitSize	Number of bits in the specific part of the counter to be incremented.

Description

This function is declared in the ippcp.h file. The function decrypts the input data stream of a variable length according to the cipher scheme specified in the [NIST SP 800-38A] recommendation. The function uses three sets of the supplied round keys. The standard incrementing function is applied to increment value of counter. The function returns the ciphertext result.

Return Values

ippStsNoErr	Indicates no error. Any other value indicates an error or warning.
ippStsNullPtrErr	Indicates an error condition if any of the specified pointers is NULL.
ippStsLengthErr	Indicates an error condition if the descrypted plaintext data stream length is less that or equal to zero.
ippStsCTRSizeErr	Indicates an error condition if the value of the ctrNumBitSize is illegal.
ippStsContextMatchErr	Indicates an error condition if the context parameter does not match the operation.