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MLKEM: check public key when decoding #9621

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Merged
dgarske merged 1 commit into from
Jan 7, 2026
+28 −1
Merged

MLKEM: check public key when decoding #9621

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4 changes: 3 additions & 1 deletion wolfcrypt/src/wc_mlkem.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1793,7 +1793,9 @@ int wc_MlKemKey_DecodePublicKey(MlKemKey* key, const unsigned char* in,

if (ret == 0) {
mlkemkey_decode_public(key->pub, key->pubSeed, p, k);

ret = mlkem_check_public(key->pub, k);
}
if (ret == 0) {
/* Calculate public hash. */
ret = MLKEM_HASH_H(&key->hash, in, len, key->h);
}
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23 changes: 23 additions & 0 deletions wolfcrypt/src/wc_mlkem_poly.c
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Expand Up @@ -6074,4 +6074,27 @@ void mlkem_to_bytes(byte* b, sword16* p, int k)
}
}

/**
* Check the public key values are smaller than the modulus.
*
* @param [in] pub Public key - vector.
* @param [in] k Number of polynomials in vector.
* @return 0 when all values are in range.
* @return PUBLIC_KEY_E when at least one value is out of range.
*/
int mlkem_check_public(sword16* pub, int k)
{
int ret = 0;
int i;

for (i = 0; i < k * MLKEM_N; i++) {
if (pub[i] >= MLKEM_Q) {
ret = PUBLIC_KEY_E;
break;
}
}

return ret;
}

#endif /* WOLFSSL_WC_MLKEM */
2 changes: 2 additions & 0 deletions wolfssl/wolfcrypt/wc_mlkem.h
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Expand Up @@ -238,6 +238,8 @@ WOLFSSL_LOCAL
void mlkem_from_bytes(sword16* p, const byte* b, int k);
WOLFSSL_LOCAL
void mlkem_to_bytes(byte* b, sword16* p, int k);
WOLFSSL_LOCAL
int mlkem_check_public(sword16* p, int k);

#ifdef USE_INTEL_SPEEDUP
WOLFSSL_LOCAL
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