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ot_aes: fix IV and CTR issues (cherry-pick #98) #100

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Merged
merged 3 commits into from
Jan 16, 2025
Merged

ot_aes: fix IV and CTR issues (cherry-pick #98) #100

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a92fb79
[ot] hw/opentitan: ot_aes: fix invalid IV size definition
rivos-eblot Jan 13, 2025
52e61e0
[ot] hw/opentitan: ot_aes: fix invalid register reference to read cur…
rivos-eblot Jan 13, 2025
ff32436
[ot] hw/opentitan: ot_aes: compute next round CTR/IV value.
rivos-eblot Jan 13, 2025
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28 changes: 25 additions & 3 deletions hw/opentitan/ot_aes.c
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Original file line number Diff line number Diff line change
Expand Up @@ -122,7 +122,7 @@ REG32(STATUS, 0x84u)

#define OT_AES_DATA_SIZE (PARAM_NUM_REGS_DATA * sizeof(uint32_t))
#define OT_AES_KEY_SIZE (PARAM_NUM_REGS_KEY * sizeof(uint32_t))
#define OT_AES_IV_SIZE (PARAM_NUM_REGS_KEY * sizeof(uint32_t))
#define OT_AES_IV_SIZE (PARAM_NUM_REGS_IV * sizeof(uint32_t))

/* arbitrary value long enough to give back execution to vCPU */
#define OT_AES_RETARD_DELAY_NS 10000u /* 10 us */
Expand Down Expand Up @@ -754,6 +754,28 @@ static void ot_aes_finalize(OtAESState *s, enum OtAESMode mode)
c->do_full = false;
}

static void ot_aes_compute_ctr_iv(OtAESState *s, uint8_t *iv)
{
OtAESContext *c = s->ctx;
uint8_t liv[OT_AES_IV_SIZE];

unsigned long length = OT_AES_IV_SIZE;
ctr_getiv(liv, &length, &c->ctr);

g_assert(c->ctr.mode == CTR_COUNTER_BIG_ENDIAN);
g_assert(c->ctr.ctrlen == 0);

unsigned ix = OT_AES_IV_SIZE - 1u;
do {
liv[ix] = liv[ix] + 0x1u;
if (liv[ix] != 0) {
break;
}
} while (ix--);

memcpy(iv, liv, sizeof(liv));
}

static void ot_aes_pop(OtAESState *s)
{
OtAESRegisters *r = s->regs;
Expand Down Expand Up @@ -854,7 +876,7 @@ static void ot_aes_process(OtAESState *s)
memcpy(c->iv, c->ofb.IV, sizeof(c->iv));
break;
case AES_CTR:
memcpy(c->iv, c->ctr.ctr, sizeof(c->iv));
ot_aes_compute_ctr_iv(s, (uint8_t *)&c->iv[0]);
break;
default:
break;
Expand Down Expand Up @@ -1009,7 +1031,7 @@ static uint64_t ot_aes_read(void *opaque, hwaddr addr, unsigned size)
case R_IV_1:
case R_IV_2:
case R_IV_3:
val32 = r->keyshare[reg - R_IV_0];
val32 = r->iv[reg - R_IV_0];
break;
case R_DATA_OUT_0:
case R_DATA_OUT_1:
Expand Down
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