AES_GCMGetTag

Generates the authentication tag in the GCM mode.

Syntax

IppStatus ippsAES_GCMGetTag (Ipp8u* pTag, int tagLen, const IppsAES_GCMState* pState);

Include Files

ippcp.h

Parameters

pTag	Pointer to the authentication tag.
tagLen	Length of the authentication tag *pTag (in bytes).
pState	Pointer to the IppsAES_GCMState context.

Description

The function generates and computes the authentication tag of length tagLen according to GCM as specified in NIST SP 800-38D. A call to ippsAES_GCMGetTag does not stop the process of authenticated encryption/decryption.

Warning

If the application continues to encrypt or decrypt data after calling ippsAES_GCMGetTag, a final ippsAES_GCMGetTag MUST be called to authenticate the appended data. Intermediate tags do not cover data appended subsequently.

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.
ippStsContextMatchErr	Indicates an error condition if the context parameter does not match the operation.
ippStsLengthErr	Indicates an error condition if tagLen <1 or taglen >16.
ippStsBadArgErr	Indicates an error condition if the pState parameter value is GcmInit or a non-empty IV has not been processed. This means that the function call sequence is illegal.