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LMS - check sum fix for SHA-256-192

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Only 8 bits needed of checksum whem doing 192-bit hashes with Winternitz
of 1 (9 for 256-bit hashes).
Cleanup code around checksum.
This commit is contained in:
Sean Parkinson
2025-11-18 20:46:57 +10:00
parent 46a7719e2d
commit da0e4f59ec
1 changed files with 16 additions and 12 deletions
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28
wolfcrypt/src/wc_lms_impl.c
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@@ -671,7 +671,6 @@ static WC_INLINE int wc_lmots_q_expand(byte* q, word8 n, word8 w, word8 ls,
/* For each byte of the hash. */
for (i = 0; i < n; i++) {
/* Get coefficients. */
qe[0] = (q[i] >> 4) ;
qe[0] = (q[i] >> 6) ;
qe[1] = (q[i] >> 4) & 0x3;
qe[2] = (q[i] >> 2) & 0x3;
@@ -697,7 +696,6 @@ static WC_INLINE int wc_lmots_q_expand(byte* q, word8 n, word8 w, word8 ls,
/* For each byte of the hash. */
for (i = 0; i < n; i++) {
/* Get coefficients. */
qe[0] = (q[i] >> 4) ;
qe[0] = (q[i] >> 7) ;
qe[1] = (q[i] >> 6) & 0x1;
qe[2] = (q[i] >> 5) & 0x1;
@@ -719,15 +717,21 @@ static WC_INLINE int wc_lmots_q_expand(byte* q, word8 n, word8 w, word8 ls,
qe += 8;
}
/* Put coefficients of checksum on the end. */
qe[0] = (word8)((sum >> 8) );
qe[1] = (word8)((sum >> 7) & 0x1);
qe[2] = (word8)((sum >> 6) & 0x1);
qe[3] = (word8)((sum >> 5) & 0x1);
qe[4] = (word8)((sum >> 4) & 0x1);
qe[5] = (word8)((sum >> 3) & 0x1);
qe[6] = (word8)((sum >> 2) & 0x1);
qe[7] = (word8)((sum >> 1) & 0x1);
qe[8] = (word8)((sum ) & 0x1);
#ifdef WOLFSSL_LMS_SHA256_192
if (ls == 7)
#endif
{
qe[0] = (word8)((sum >> 8) );
qe++;
}
qe[0] = (word8)((sum >> 7) & 0x1);
qe[1] = (word8)((sum >> 6) & 0x1);
qe[2] = (word8)((sum >> 5) & 0x1);
qe[3] = (word8)((sum >> 4) & 0x1);
qe[4] = (word8)((sum >> 3) & 0x1);
qe[5] = (word8)((sum >> 2) & 0x1);
qe[6] = (word8)((sum >> 1) & 0x1);
qe[7] = (word8)((sum ) & 0x1);
break;
default:
ret = BAD_FUNC_ARG;
@@ -763,7 +767,7 @@ static WC_INLINE int wc_lmots_q_expand(byte* q, word8 n, word8 w, word8 ls,
}
/* Shift sum up as required to pack it on the end of hash. */
sum <<= ls;
/* For each width buts of checksum. */
/* For each width bit of checksum. */
for (j = 16 - w; j >= ls; j--) {
/* Get coefficient. */
*(qe++) = sum >> (16 - w);