Problem - Kevin Tafuro

int spc_omac1_init(SPC_OMAC_CTX *ctx, unsigned char *key, int keylen);
int spc_omac2_init(SPC_OMAC_CTX *ctx, unsigned char *key, int keylen);
These functions have the following arguments:
ctx
Context object to be initialized.
key
Block cipher key.
keylen
Length of the key in bytes. The length of the key must be 16, 24, or 32 bytes; any
other key length is invalid.
Once initialized, spc_omac_update( ) can be used to process data. Note that the only
differences between OMAC1 and OMAC2 in this implementation are handled at key
setup time, so they both use the same functions for updating and finalization. Multiple
calls to spc_omac_update( ) act just like making a single call where all of the data
was concatenated together. Here is its signature:
void spc_omac_update(SPC_OMAC_CTX *ctx, unsigned char *in, size_t il);
This function has the following arguments:
ctx
Context object to use for the current message.
in
Buffer that contains the data to be processed.
il
Length of the data buffer to be processed in bytes.
To obtain the output of the MAC operation, call spc_omac_final( ), which has the
following signature:
int spc_omac_final(SPC_OMAC_CTX *ctx, unsigned char *out);
This function has the following arguments:
ctx
Context object to be finalized.
out
Buffer into which the output will be placed. This buffer must be at least 16 bytes
in size. No more than 16 bytes will ever be written to it.
Here is the code implementing OMAC:
#include
typedef struct {
SPC_KEY_SCHED ks;
int ix;
unsigned char iv[SPC_BLOCK_SZ];
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