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/* Copyright 2015 The ChromiumOS Authors
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "dcrypto.h"
#include "internal.h"
#include "registers.h"
static void set_control_register(
unsigned mode, unsigned key_size, unsigned encrypt)
{
GWRITE_FIELD(KEYMGR, AES_CTRL, RESET, CTRL_NO_SOFT_RESET);
GWRITE_FIELD(KEYMGR, AES_CTRL, KEYSIZE, key_size);
GWRITE_FIELD(KEYMGR, AES_CTRL, CIPHER_MODE, mode);
GWRITE_FIELD(KEYMGR, AES_CTRL, ENC_MODE, encrypt);
GWRITE_FIELD(KEYMGR, AES_CTRL, CTR_ENDIAN, CTRL_CTR_BIG_ENDIAN);
GWRITE_FIELD(KEYMGR, AES_CTRL, ENABLE, CTRL_ENABLE);
/* Turn off random nops (which are enabled by default). */
GWRITE_FIELD(KEYMGR, AES_RAND_STALL_CTL, STALL_EN, 0);
/* Configure random nop percentage at 25%. */
GWRITE_FIELD(KEYMGR, AES_RAND_STALL_CTL, FREQ, 1);
/* Now turn on random nops. */
GWRITE_FIELD(KEYMGR, AES_RAND_STALL_CTL, STALL_EN, 1);
}
static int wait_read_data(volatile uint32_t *addr)
{
int empty;
int count = 20; /* Wait these many ~cycles. */
do {
empty = REG32(addr);
count--;
} while (count && empty);
return empty ? 0 : 1;
}
int DCRYPTO_aes_init(const uint8_t *key, uint32_t key_len, const uint8_t *iv,
enum cipher_mode c_mode, enum encrypt_mode e_mode)
{
int i;
const struct access_helper *p;
uint32_t key_mode;
switch (key_len) {
case 128:
key_mode = 0;
break;
case 192:
key_mode = 1;
break;
case 256:
key_mode = 2;
break;
default:
/* Invalid key length specified. */
return 0;
}
set_control_register(c_mode, key_mode, e_mode);
/* Initialize hardware with AES key */
p = (struct access_helper *) key;
for (i = 0; i < (key_len >> 5); i++)
GR_KEYMGR_AES_KEY(i) = p[i].udata;
/* Trigger key expansion. */
GREG32(KEYMGR, AES_KEY_START) = 1;
/* Wait for key expansion. */
if (!wait_read_data(GREG32_ADDR(KEYMGR, AES_KEY_START))) {
/* Should not happen. */
return 0;
}
/* Initialize IV for modes that require it. */
if (iv) {
p = (struct access_helper *) iv;
for (i = 0; i < 4; i++)
GR_KEYMGR_AES_CTR(i) = p[i].udata;
}
return 1;
}
int DCRYPTO_aes_block(const uint8_t *in, uint8_t *out)
{
int i;
struct access_helper *outw;
const struct access_helper *inw = (struct access_helper *) in;
/* Write plaintext. */
for (i = 0; i < 4; i++)
GREG32(KEYMGR, AES_WFIFO_DATA) = inw[i].udata;
/* Wait for the result. */
if (!wait_read_data(GREG32_ADDR(KEYMGR, AES_RFIFO_EMPTY))) {
/* Should not happen, ciphertext not ready. */
return 0;
}
/* Read ciphertext. */
outw = (struct access_helper *) out;
for (i = 0; i < 4; i++)
outw[i].udata = GREG32(KEYMGR, AES_RFIFO_DATA);
return 1;
}
void DCRYPTO_aes_write_iv(const uint8_t *iv)
{
int i;
const struct access_helper *p = (const struct access_helper *) iv;
for (i = 0; i < 4; i++)
GR_KEYMGR_AES_CTR(i) = p[i].udata;
}
void DCRYPTO_aes_read_iv(uint8_t *iv)
{
int i;
struct access_helper *p = (struct access_helper *) iv;
for (i = 0; i < 4; i++)
p[i].udata = GR_KEYMGR_AES_CTR(i);
}
int DCRYPTO_aes_ctr(uint8_t *out, const uint8_t *key, uint32_t key_bits,
const uint8_t *iv, const uint8_t *in, size_t in_len)
{
/* Initialize AES hardware. */
if (!DCRYPTO_aes_init(key, key_bits, iv,
CIPHER_MODE_CTR, ENCRYPT_MODE))
return 0;
while (in_len > 0) {
uint8_t tmpin[16];
uint8_t tmpout[16];
const uint8_t *inp;
uint8_t *outp;
const size_t count = MIN(in_len, 16);
if (count < 16) {
memcpy(tmpin, in, count);
inp = tmpin;
outp = tmpout;
} else {
inp = in;
outp = out;
}
if (!DCRYPTO_aes_block(inp, outp))
return 0;
if (outp != out)
memcpy(out, outp, count);
in += count;
out += count;
in_len -= count;
}
return 1;
}
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