/**
* Applies or removes a PKCS#1 v2.1 encryption padding.
*
* @param[out] m - the buffer to pad.
* @param[out] p_len - the number of added pad bytes.
* @param[in] m_len - the message length in bytes.
* @param[in] k_len - the key length in bytes.
* @param[in] operation - flag to indicate the operation type.
* @return STS_ERR if errors occurred, STS_OK otherwise.
*/
static int pad_pkcs2(bn_t m, int *p_len, int m_len, int k_len, int operation) {
uint8_t pad, h1[MD_LEN], h2[MD_LEN], mask[k_len];
int result = STS_OK;
bn_t t;
bn_null(t);
TRY {
bn_new(t);
switch (operation) {
case RSA_ENC:
/* DB = lHash | PS | 01 | D. */
md_map(h1, NULL, 0);
bn_read_bin(m, h1, MD_LEN);
*p_len = k_len - 2 * MD_LEN - 2 - m_len;
bn_lsh(m, m, *p_len * 8);
bn_lsh(m, m, 8);
bn_add_dig(m, m, 0x01);
/* Make room for the real message. */
bn_lsh(m, m, m_len * 8);
break;
case RSA_ENC_FIN:
/* EB = 00 | maskedSeed | maskedDB. */
rand_bytes(h1, MD_LEN);
md_mgf1(mask, k_len - MD_LEN - 1, h1, MD_LEN);
bn_read_bin(t, mask, k_len - MD_LEN - 1);
for (int i = 0; i < t->used; i++) {
m->dp[i] ^= t->dp[i];
}
bn_write_bin(mask, k_len - MD_LEN - 1, m);
md_mgf1(h2, MD_LEN, mask, k_len - MD_LEN - 1);
for (int i = 0; i < MD_LEN; i++) {
h1[i] ^= h2[i];
}
bn_read_bin(t, h1, MD_LEN);
bn_lsh(t, t, 8 * (k_len - MD_LEN - 1));
bn_add(t, t, m);
bn_copy(m, t);
break;
case RSA_DEC:
m_len = k_len - 1;
bn_rsh(t, m, 8 * m_len);
if (!bn_is_zero(t)) {
result = STS_ERR;
}
m_len -= MD_LEN;
bn_rsh(t, m, 8 * m_len);
bn_write_bin(h1, MD_LEN, t);
bn_mod_2b(m, m, 8 * m_len);
bn_write_bin(mask, m_len, m);
md_mgf1(h2, MD_LEN, mask, m_len);
for (int i = 0; i < MD_LEN; i++) {
h1[i] ^= h2[i];
}
md_mgf1(mask, k_len - MD_LEN - 1, h1, MD_LEN);
bn_read_bin(t, mask, k_len - MD_LEN - 1);
for (int i = 0; i < t->used; i++) {
m->dp[i] ^= t->dp[i];
}
m_len -= MD_LEN;
bn_rsh(t, m, 8 * m_len);
bn_write_bin(h2, MD_LEN, t);
md_map(h1, NULL, 0);
pad = 0;
for (int i = 0; i < MD_LEN; i++) {
pad |= h1[i] - h2[i];
}
if (result == STS_OK) {
result = (pad ? STS_ERR : STS_OK);
}
bn_mod_2b(m, m, 8 * m_len);
*p_len = bn_size_bin(m);
(*p_len)--;
bn_rsh(t, m, *p_len * 8);
if (bn_cmp_dig(t, 1) != CMP_EQ) {
result = STS_ERR;
}
bn_mod_2b(m, m, *p_len * 8);
*p_len = k_len - *p_len;
break;
case RSA_SIG:
case RSA_SIG_HASH:
/* M' = 00 00 00 00 00 00 00 00 | H(M). */
bn_zero(m);
bn_lsh(m, m, 64);
/* Make room for the real message. */
bn_lsh(m, m, MD_LEN * 8);
break;
case RSA_SIG_FIN:
memset(mask, 0, 8);
bn_write_bin(mask + 8, MD_LEN, m);
md_map(h1, mask, MD_LEN + 8);
bn_read_bin(m, h1, MD_LEN);
md_mgf1(mask, k_len - MD_LEN - 1, h1, MD_LEN);
bn_read_bin(t, mask, k_len - MD_LEN - 1);
t->dp[0] ^= 0x01;
/* m_len is now the size in bits of the modulus. */
bn_lsh(t, t, 8 * MD_LEN);
bn_add(m, t, m);
bn_lsh(m, m, 8);
bn_add_dig(m, m, RSA_PSS);
for (int i = m_len - 1; i < 8 * k_len; i++) {
bn_set_bit(m, i, 0);
}
break;
case RSA_VER:
case RSA_VER_HASH:
bn_mod_2b(t, m, 8);
if (bn_cmp_dig(t, RSA_PSS) != CMP_EQ) {
result = STS_ERR;
} else {
for (int i = m_len; i < 8 * k_len; i++) {
if (bn_get_bit(m, i) != 0) {
result = STS_ERR;
}
}
bn_rsh(m, m, 8);
bn_mod_2b(t, m, 8 * MD_LEN);
bn_write_bin(h2, MD_LEN, t);
bn_rsh(m, m, 8 * MD_LEN);
bn_write_bin(h1, MD_LEN, t);
md_mgf1(mask, k_len - MD_LEN - 1, h1, MD_LEN);
bn_read_bin(t, mask, k_len - MD_LEN - 1);
for (int i = 0; i < t->used; i++) {
m->dp[i] ^= t->dp[i];
}
m->dp[0] ^= 0x01;
for (int i = m_len - 1; i < 8 * k_len; i++) {
bn_set_bit(m, i - ((MD_LEN + 1) * 8), 0);
}
if (!bn_is_zero(m)) {
result = STS_ERR;
}
bn_read_bin(m, h2, MD_LEN);
*p_len = k_len - MD_LEN;
}
break;
}
}
CATCH_ANY {
result = STS_ERR;
}
FINALLY {
bn_free(t);
}
return result;
}
int cp_rsa_enc(uint8_t *out, int *out_len, uint8_t *in, int in_len, rsa_t pub) {
bn_t m, eb;
int size, pad_len, result = STS_OK;
bn_null(m);
bn_null(eb);
bn_size_bin(&size, pub->n);
if (pub == NULL || in_len <= 0 || in_len > (size - RSA_PAD_LEN)) {
return STS_ERR;
}
TRY {
bn_new(m);
bn_new(eb);
bn_zero(m);
bn_zero(eb);
#if CP_RSAPD == BASIC
if (pad_basic(eb, &pad_len, in_len, size, RSA_ENC) == STS_OK) {
#elif CP_RSAPD == PKCS1
if (pad_pkcs1(eb, &pad_len, in_len, size, RSA_ENC) == STS_OK) {
#elif CP_RSAPD == PKCS2
if (pad_pkcs2(eb, &pad_len, in_len, size, RSA_ENC) == STS_OK) {
#endif
bn_read_bin(m, in, in_len);
bn_add(eb, eb, m);
#if CP_RSAPD == PKCS2
pad_pkcs2(eb, &pad_len, in_len, size, RSA_ENC_FIN);
#endif
bn_mxp(eb, eb, pub->e, pub->n);
if (size <= *out_len) {
*out_len = size;
memset(out, 0, *out_len);
bn_write_bin(out, size, eb);
} else {
result = STS_ERR;
}
} else {
result = STS_ERR;
}
}
CATCH_ANY {
result = STS_ERR;
}
FINALLY {
bn_free(m);
bn_free(eb);
}
return result;
}
#if CP_RSA == BASIC || !defined(STRIP)
int cp_rsa_dec_basic(uint8_t *out, int *out_len, uint8_t *in, int in_len, rsa_t prv) {
bn_t m, eb;
int size, pad_len, result = STS_OK;
bn_size_bin(&size, prv->n);
if (prv == NULL || in_len != size || in_len < RSA_PAD_LEN) {
return STS_ERR;
}
bn_null(m);
bn_null(eb);
TRY {
bn_new(m);
bn_new(eb);
bn_read_bin(eb, in, in_len);
bn_mxp(eb, eb, prv->d, prv->n);
if (bn_cmp(eb, prv->n) != CMP_LT) {
result = STS_ERR;
}
#if CP_RSAPD == BASIC
if (pad_basic(eb, &pad_len, in_len, size, RSA_DEC) == STS_OK) {
#elif CP_RSAPD == PKCS1
if (pad_pkcs1(eb, &pad_len, in_len, size, RSA_DEC) == STS_OK) {
#elif CP_RSAPD == PKCS2
if (pad_pkcs2(eb, &pad_len, in_len, size, RSA_DEC) == STS_OK) {
#endif
size = size - pad_len;
if (size <= *out_len) {
memset(out, 0, size);
bn_write_bin(out, size, eb);
*out_len = size;
} else {
result = STS_ERR;
}
} else {
result = STS_ERR;
}
}
CATCH_ANY {
result = STS_ERR;
}
FINALLY {
bn_free(m);
bn_free(eb);
}
return result;
}
#endif
#if CP_RSA == QUICK || !defined(STRIP)
int cp_rsa_dec_quick(uint8_t *out, int *out_len, uint8_t *in, int in_len, rsa_t prv) {
bn_t m, eb;
int size, pad_len, result = STS_OK;
bn_null(m);
bn_null(eb);
bn_size_bin(&size, prv->n);
if (prv == NULL || in_len != size || in_len < RSA_PAD_LEN) {
return STS_ERR;
}
TRY {
bn_new(m);
bn_new(eb);
bn_read_bin(eb, in, in_len);
bn_copy(m, eb);
/* m1 = c^dP mod p. */
bn_mxp(eb, eb, prv->dp, prv->p);
/* m2 = c^dQ mod q. */
bn_mxp(m, m, prv->dq, prv->q);
/* m1 = m1 - m2 mod p. */
bn_sub(eb, eb, m);
while (bn_sign(eb) == BN_NEG) {
bn_add(eb, eb, prv->p);
}
bn_mod(eb, eb, prv->p);
/* m1 = qInv(m1 - m2) mod p. */
bn_mul(eb, eb, prv->qi);
bn_mod(eb, eb, prv->p);
/* m = m2 + m1 * q. */
bn_mul(eb, eb, prv->q);
bn_add(eb, eb, m);
if (bn_cmp(eb, prv->n) != CMP_LT) {
result = STS_ERR;
}
#if CP_RSAPD == BASIC
if (pad_basic(eb, &pad_len, in_len, size, RSA_DEC) == STS_OK) {
#elif CP_RSAPD == PKCS1
if (pad_pkcs1(eb, &pad_len, in_len, size, RSA_DEC) == STS_OK) {
#elif CP_RSAPD == PKCS2
if (pad_pkcs2(eb, &pad_len, in_len, size, RSA_DEC) == STS_OK) {
#endif
size = size - pad_len;
if (size <= *out_len) {
memset(out, 0, size);
bn_write_bin(out, size, eb);
*out_len = size;
} else {
result = STS_ERR;
}
} else {
result = STS_ERR;
}
}
CATCH_ANY {
result = STS_ERR;
}
FINALLY {
bn_free(m);
bn_free(eb);
}
return result;
}
#endif
#if CP_RSA == BASIC || !defined(STRIP)
int cp_rsa_sig_basic(uint8_t *sig, int *sig_len, uint8_t *msg, int msg_len, int hash, rsa_t prv) {
bn_t m, eb;
int size, pad_len, result = STS_OK;
uint8_t h[MD_LEN];
if (prv == NULL || msg_len < 0) {
return STS_ERR;
}
pad_len = (!hash ? MD_LEN : msg_len);
#if CP_RSAPD == PKCS2
size = bn_bits(prv->n) - 1;
size = (size / 8) + (size % 8 > 0);
if (pad_len > (size - 2)) {
return STS_ERR;
}
#else
bn_size_bin(&size, prv->n);
if (pad_len > (size - RSA_PAD_LEN)) {
return STS_ERR;
}
#endif
bn_null(m);
bn_null(eb);
TRY {
bn_new(m);
bn_new(eb);
bn_zero(m);
bn_zero(eb);
int operation = (!hash ? RSA_SIG : RSA_SIG_HASH);
#if CP_RSAPD == BASIC
if (pad_basic(eb, &pad_len, pad_len, size, operation) == STS_OK) {
#elif CP_RSAPD == PKCS1
if (pad_pkcs1(eb, &pad_len, pad_len, size, operation) == STS_OK) {
#elif CP_RSAPD == PKCS2
if (pad_pkcs2(eb, &pad_len, pad_len, size, operation) == STS_OK) {
#endif
if (!hash) {
md_map(h, msg, msg_len);
bn_read_bin(m, h, MD_LEN);
bn_add(eb, eb, m);
} else {
bn_read_bin(m, msg, msg_len);
bn_add(eb, eb, m);
}
#if CP_RSAPD == PKCS2
pad_pkcs2(eb, &pad_len, bn_bits(prv->n), size, RSA_SIG_FIN);
#endif
bn_mxp(eb, eb, prv->d, prv->n);
bn_size_bin(&size, prv->n);
if (size <= *sig_len) {
memset(sig, 0, size);
bn_write_bin(sig, size, eb);
*sig_len = size;
} else {
result = STS_ERR;
}
} else {
result = STS_ERR;
}
}
CATCH_ANY {
THROW(ERR_CAUGHT);
}
FINALLY {
bn_free(m);
bn_free(eb);
}
return result;
}
#endif
#if CP_RSA == QUICK || !defined(STRIP)
int cp_rsa_sig_quick(uint8_t *sig, int *sig_len, uint8_t *msg, int msg_len, int hash, rsa_t prv) {
bn_t m, eb;
int pad_len, size, result = STS_OK;
uint8_t h[MD_LEN];
if (prv == NULL || msg_len < 0) {
return STS_ERR;
}
pad_len = (!hash ? MD_LEN : msg_len);
#if CP_RSAPD == PKCS2
size = bn_bits(prv->n) - 1;
size = (size / 8) + (size % 8 > 0);
if (pad_len > (size - 2)) {
return STS_ERR;
}
#else
bn_size_bin(&size, prv->n);
if (pad_len > (size - RSA_PAD_LEN)) {
return STS_ERR;
}
#endif
bn_null(m);
bn_null(eb);
TRY {
bn_new(m);
bn_new(eb);
bn_zero(m);
bn_zero(eb);
int operation = (!hash ? RSA_SIG : RSA_SIG_HASH);
#if CP_RSAPD == BASIC
if (pad_basic(eb, &pad_len, pad_len, size, operation) == STS_OK) {
#elif CP_RSAPD == PKCS1
if (pad_pkcs1(eb, &pad_len, pad_len, size, operation) == STS_OK) {
#elif CP_RSAPD == PKCS2
if (pad_pkcs2(eb, &pad_len, pad_len, size, operation) == STS_OK) {
#endif
if (!hash) {
md_map(h, msg, msg_len);
bn_read_bin(m, h, MD_LEN);
bn_add(eb, eb, m);
} else {
bn_read_bin(m, msg, msg_len);
bn_add(eb, eb, m);
}
#if CP_RSAPD == PKCS2
pad_pkcs2(eb, &pad_len, bn_bits(prv->n), size, RSA_SIG_FIN);
#endif
bn_copy(m, eb);
/* m1 = c^dP mod p. */
bn_mxp(eb, eb, prv->dp, prv->p);
/* m2 = c^dQ mod q. */
bn_mxp(m, m, prv->dq, prv->q);
/* m1 = m1 - m2 mod p. */
bn_sub(eb, eb, m);
while (bn_sign(eb) == BN_NEG) {
bn_add(eb, eb, prv->p);
}
bn_mod(eb, eb, prv->p);
/* m1 = qInv(m1 - m2) mod p. */
bn_mul(eb, eb, prv->qi);
bn_mod(eb, eb, prv->p);
/* m = m2 + m1 * q. */
bn_mul(eb, eb, prv->q);
bn_add(eb, eb, m);
bn_mod(eb, eb, prv->n);
bn_size_bin(&size, prv->n);
if (size <= *sig_len) {
memset(sig, 0, size);
bn_write_bin(sig, size, eb);
*sig_len = size;
} else {
result = STS_ERR;
}
} else {
result = STS_ERR;
}
}
CATCH_ANY {
THROW(ERR_CAUGHT);
}
FINALLY {
bn_free(m);
bn_free(eb);
}
return result;
}
#endif
int cp_rsa_ver(uint8_t *sig, int sig_len, uint8_t *msg, int msg_len, int hash, rsa_t pub) {
bn_t m, eb;
int size, pad_len, result;
uint8_t h1[MAX(msg_len, MD_LEN) + 8], h2[MAX(msg_len, MD_LEN)];
/* We suppose that the signature is invalid. */
result = 0;
if (pub == NULL || msg_len < 0) {
return 0;
}
pad_len = (!hash ? MD_LEN : msg_len);
#if CP_RSAPD == PKCS2
size = bn_bits(pub->n) - 1;
if (size % 8 == 0) {
size = size / 8 - 1;
} else {
bn_size_bin(&size, pub->n);
}
if (pad_len > (size - 2)) {
return 0;
}
#else
bn_size_bin(&size, pub->n);
if (pad_len > (size - RSA_PAD_LEN)) {
return 0;
}
#endif
bn_null(m);
bn_null(eb);
TRY {
bn_new(m);
bn_new(eb);
bn_read_bin(eb, sig, sig_len);
bn_mxp(eb, eb, pub->e, pub->n);
int operation = (!hash ? RSA_VER : RSA_VER_HASH);
#if CP_RSAPD == BASIC
if (pad_basic(eb, &pad_len, MD_LEN, size, operation) == STS_OK) {
#elif CP_RSAPD == PKCS1
if (pad_pkcs1(eb, &pad_len, MD_LEN, size, operation) == STS_OK) {
#elif CP_RSAPD == PKCS2
if (pad_pkcs2(eb, &pad_len, bn_bits(pub->n), size, operation) == STS_OK) {
#endif
#if CP_RSAPD == PKCS2
memset(h1, 0, 8);
if (!hash) {
md_map(h1 + 8, msg, msg_len);
md_map(h2, h1, MD_LEN + 8);
memset(h1, 0, MD_LEN);
bn_write_bin(h1, size - pad_len, eb);
/* Everything went ok, so signature status is changed. */
result = util_cmp_const(h1, h2, MD_LEN);
} else {
memcpy(h1 + 8, msg, msg_len);
md_map(h2, h1, MD_LEN + 8);
memset(h1, 0, msg_len);
bn_write_bin(h1, size - pad_len, eb);
/* Everything went ok, so signature status is changed. */
result = util_cmp_const(h1, h2, msg_len);
}
#else
memset(h1, 0, MAX(msg_len, MD_LEN));
bn_write_bin(h1, size - pad_len, eb);
if (!hash) {
md_map(h2, msg, msg_len);
/* Everything went ok, so signature status is changed. */
result = util_cmp_const(h1, h2, MD_LEN);
} else {
/* Everything went ok, so signature status is changed. */
result = util_cmp_const(h1, msg, msg_len);
}
#endif
result = (result == CMP_EQ ? 1 : 0);
} else {
result = 0;
}
}
CATCH_ANY {
result = 0;
}
FINALLY {
bn_free(m);
bn_free(eb);
}
return result;
}