/* finalize the hash computation and output the result */
int Skein_256_Final(Skein_256_Ctxt_t *ctx, u08b_t *hashVal)
{
size_t i,n,byteCnt;
u64b_t X[SKEIN_256_STATE_WORDS];
Skein_Assert(ctx->h.bCnt <= SKEIN_256_BLOCK_BYTES,SKEIN_FAIL); /* catch uninitialized context */
ctx->h.T[1] |= SKEIN_T1_FLAG_FINAL; /* tag as the final block */
if (ctx->h.bCnt < SKEIN_256_BLOCK_BYTES) /* zero pad b[] if necessary */
memset(&ctx->b[ctx->h.bCnt],0,SKEIN_256_BLOCK_BYTES - ctx->h.bCnt);
Skein_256_Process_Block(ctx,ctx->b,1,ctx->h.bCnt); /* process the final block */
/* now output the result */
byteCnt = (ctx->h.hashBitLen + 7) >> 3; /* total number of output bytes */
/* run Threefish in "counter mode" to generate output */
memset(ctx->b,0,sizeof(ctx->b)); /* zero out b[], so it can hold the counter */
memcpy(X,ctx->X,sizeof(X)); /* keep a local copy of counter mode "key" */
for (i=0;i*SKEIN_256_BLOCK_BYTES < byteCnt;i++)
{
((u64b_t *)ctx->b)[0]= Skein_Swap64((u64b_t) i); /* build the counter block */
Skein_Start_New_Type(ctx,OUT_FINAL);
Skein_256_Process_Block(ctx,ctx->b,1,sizeof(u64b_t)); /* run "counter mode" */
n = byteCnt - i*SKEIN_256_BLOCK_BYTES; /* number of output bytes left to go */
if (n >= SKEIN_256_BLOCK_BYTES)
n = SKEIN_256_BLOCK_BYTES;
Skein_Put64_LSB_First(hashVal+i*SKEIN_256_BLOCK_BYTES,ctx->X,n); /* "output" the ctr mode bytes */
Skein_Show_Final(256,&ctx->h,n,hashVal+i*SKEIN_256_BLOCK_BYTES);
memcpy(ctx->X,X,sizeof(X)); /* restore the counter mode key for next time */
}
return SKEIN_SUCCESS;
}
/* process the input bytes */
int
Skein_256_Update(Skein_256_Ctxt_t *ctx, const uint8_t *msg, size_t msgByteCnt)
{
size_t n;
/* catch uninitialized context */
Skein_Assert(ctx->h.bCnt <= SKEIN_256_BLOCK_BYTES, SKEIN_FAIL);
/* process full blocks, if any */
if (msgByteCnt + ctx->h.bCnt > SKEIN_256_BLOCK_BYTES) {
/* finish up any buffered message data */
if (ctx->h.bCnt) {
/* # bytes free in buffer b[] */
n = SKEIN_256_BLOCK_BYTES - ctx->h.bCnt;
if (n) {
/* check on our logic here */
Skein_assert(n < msgByteCnt);
bcopy(msg, &ctx->b[ctx->h.bCnt], n);
msgByteCnt -= n;
msg += n;
ctx->h.bCnt += n;
}
Skein_assert(ctx->h.bCnt == SKEIN_256_BLOCK_BYTES);
Skein_256_Process_Block(ctx, ctx->b, 1,
SKEIN_256_BLOCK_BYTES);
ctx->h.bCnt = 0;
}
/*
* now process any remaining full blocks, directly from input
* message data
*/
if (msgByteCnt > SKEIN_256_BLOCK_BYTES) {
/* number of full blocks to process */
n = (msgByteCnt - 1) / SKEIN_256_BLOCK_BYTES;
Skein_256_Process_Block(ctx, msg, n,
SKEIN_256_BLOCK_BYTES);
msgByteCnt -= n * SKEIN_256_BLOCK_BYTES;
msg += n * SKEIN_256_BLOCK_BYTES;
}
Skein_assert(ctx->h.bCnt == 0);
}
/* copy any remaining source message data bytes into b[] */
if (msgByteCnt) {
Skein_assert(msgByteCnt + ctx->h.bCnt <= SKEIN_256_BLOCK_BYTES);
bcopy(msg, &ctx->b[ctx->h.bCnt], msgByteCnt);
ctx->h.bCnt += msgByteCnt;
}
return (SKEIN_SUCCESS);
}
/* init the context for a straight hashing operation */
int
Skein_256_Init(Skein_256_Ctxt_t *ctx, size_t hashBitLen)
{
union {
uint8_t b[SKEIN_256_STATE_BYTES];
uint64_t w[SKEIN_256_STATE_WORDS];
} cfg; /* config block */
Skein_Assert(hashBitLen > 0, SKEIN_BAD_HASHLEN);
ctx->h.hashBitLen = hashBitLen; /* output hash bit count */
switch (hashBitLen) { /* use pre-computed values, where available */
#ifndef SKEIN_NO_PRECOMP
case 256:
bcopy(SKEIN_256_IV_256, ctx->X, sizeof (ctx->X));
break;
case 224:
bcopy(SKEIN_256_IV_224, ctx->X, sizeof (ctx->X));
break;
case 160:
bcopy(SKEIN_256_IV_160, ctx->X, sizeof (ctx->X));
break;
case 128:
bcopy(SKEIN_256_IV_128, ctx->X, sizeof (ctx->X));
break;
#endif
default:
/* here if there is no precomputed IV value available */
/*
* build/process the config block, type == CONFIG (could be
* precomputed)
*/
/* set tweaks: T0=0; T1=CFG | FINAL */
Skein_Start_New_Type(ctx, CFG_FINAL);
/* set the schema, version */
cfg.w[0] = Skein_Swap64(SKEIN_SCHEMA_VER);
/* hash result length in bits */
cfg.w[1] = Skein_Swap64(hashBitLen);
cfg.w[2] = Skein_Swap64(SKEIN_CFG_TREE_INFO_SEQUENTIAL);
/* zero pad config block */
bzero(&cfg.w[3], sizeof (cfg) - 3 * sizeof (cfg.w[0]));
/* compute the initial chaining values from config block */
/* zero the chaining variables */
bzero(ctx->X, sizeof (ctx->X));
Skein_256_Process_Block(ctx, cfg.b, 1, SKEIN_CFG_STR_LEN);
break;
}
/*
* The chaining vars ctx->X are now initialized for the given
* hashBitLen.
* Set up to process the data message portion of the hash (default)
*/
Skein_Start_New_Type(ctx, MSG); /* T0=0, T1= MSG type */
return (SKEIN_SUCCESS);
}
/* [identical to Skein_256_Init() when keyBytes == 0 && treeInfo == SKEIN_CFG_TREE_INFO_SEQUENTIAL] */
int Skein_256_InitExt(Skein_256_Ctxt_t *ctx,size_t hashBitLen,u64b_t treeInfo, const u08b_t *key, size_t keyBytes)
{
union
{
u08b_t b[SKEIN_256_STATE_BYTES];
u64b_t w[SKEIN_256_STATE_WORDS];
} cfg; /* config block */
Skein_Assert(hashBitLen > 0,SKEIN_BAD_HASHLEN);
Skein_Assert(keyBytes == 0 || key != NULL,SKEIN_FAIL);
/* compute the initial chaining values ctx->X[], based on key */
if (keyBytes == 0) /* is there a key? */
{
memset(ctx->X,0,sizeof(ctx->X)); /* no key: use all zeroes as key for config block */
}
else /* here to pre-process a key */
{
Skein_assert(sizeof(cfg.b) >= sizeof(ctx->X));
/* do a mini-Init right here */
ctx->h.hashBitLen=8*sizeof(ctx->X); /* set output hash bit count = state size */
Skein_Start_New_Type(ctx,KEY); /* set tweaks: T0 = 0; T1 = KEY type */
memset(ctx->X,0,sizeof(ctx->X)); /* zero the initial chaining variables */
Skein_256_Update(ctx,key,keyBytes); /* hash the key */
Skein_256_Final_Pad(ctx,cfg.b); /* put result into cfg.b[] */
memcpy(ctx->X,cfg.b,sizeof(cfg.b)); /* copy over into ctx->X[] */
#if SKEIN_NEED_SWAP
{
uint_t i;
for (i=0;i<SKEIN_256_STATE_WORDS;i++) /* convert key bytes to context words */
ctx->X[i] = Skein_Swap64(ctx->X[i]);
}
#endif
}
/* build/process the config block, type == CONFIG (could be precomputed for each key) */
ctx->h.hashBitLen = hashBitLen; /* output hash bit count */
Skein_Start_New_Type(ctx,CFG_FINAL);
memset(&cfg.w,0,sizeof(cfg.w)); /* pre-pad cfg.w[] with zeroes */
cfg.w[0] = Skein_Swap64(SKEIN_SCHEMA_VER);
cfg.w[1] = Skein_Swap64(hashBitLen); /* hash result length in bits */
cfg.w[2] = Skein_Swap64(treeInfo); /* tree hash config info (or SKEIN_CFG_TREE_INFO_SEQUENTIAL) */
Skein_Show_Key(256,&ctx->h,key,keyBytes);
/* compute the initial chaining values from config block */
Skein_256_Process_Block(ctx,cfg.b,1,SKEIN_CFG_STR_LEN);
/* The chaining vars ctx->X are now initialized */
/* Set up to process the data message portion of the hash (default) */
ctx->h.bCnt = 0; /* buffer b[] starts out empty */
Skein_Start_New_Type(ctx,MSG);
return SKEIN_SUCCESS;
}
/* finalize the hash computation and output the block, no OUTPUT stage */
int Skein_256_Final_Pad(Skein_256_Ctxt_t *ctx, u08b_t *hashVal)
{
Skein_Assert(ctx->h.bCnt <= SKEIN_256_BLOCK_BYTES,SKEIN_FAIL); /* catch uninitialized context */
ctx->h.T[1] |= SKEIN_T1_FLAG_FINAL; /* tag as the final block */
if (ctx->h.bCnt < SKEIN_256_BLOCK_BYTES) /* zero pad b[] if necessary */
memset(&ctx->b[ctx->h.bCnt],0,SKEIN_256_BLOCK_BYTES - ctx->h.bCnt);
Skein_256_Process_Block(ctx,ctx->b,1,ctx->h.bCnt); /* process the final block */
Skein_Put64_LSB_First(hashVal,ctx->X,SKEIN_256_BLOCK_BYTES); /* "output" the state bytes */
return SKEIN_SUCCESS;
}
/* just do the OUTPUT stage */
int
Skein_256_Output(Skein_256_Ctxt_t *ctx, uint8_t *hashVal)
{
size_t i, n, byteCnt;
uint64_t X[SKEIN_256_STATE_WORDS];
/* catch uninitialized context */
Skein_Assert(ctx->h.bCnt <= SKEIN_256_BLOCK_BYTES, SKEIN_FAIL);
/* now output the result */
/* total number of output bytes */
byteCnt = (ctx->h.hashBitLen + 7) >> 3;
/* run Threefish in "counter mode" to generate output */
/* zero out b[], so it can hold the counter */
bzero(ctx->b, sizeof (ctx->b));
/* keep a local copy of counter mode "key" */
bcopy(ctx->X, X, sizeof (X));
for (i = 0; i * SKEIN_256_BLOCK_BYTES < byteCnt; i++) {
/* build the counter block */
uint64_t tmp = Skein_Swap64((uint64_t)i);
bcopy(&tmp, ctx->b, sizeof (tmp));
Skein_Start_New_Type(ctx, OUT_FINAL);
/* run "counter mode" */
Skein_256_Process_Block(ctx, ctx->b, 1, sizeof (uint64_t));
/* number of output bytes left to go */
n = byteCnt - i * SKEIN_256_BLOCK_BYTES;
if (n >= SKEIN_256_BLOCK_BYTES)
n = SKEIN_256_BLOCK_BYTES;
Skein_Put64_LSB_First(hashVal + i * SKEIN_256_BLOCK_BYTES,
ctx->X, n); /* "output" the ctr mode bytes */
Skein_Show_Final(256, &ctx->h, n,
hashVal + i * SKEIN_256_BLOCK_BYTES);
/* restore the counter mode key for next time */
bcopy(X, ctx->X, sizeof (X));
}
return (SKEIN_SUCCESS);
}
