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mbedtls/library/pkwrite.c
Gilles Peskine 449bd8303e Switch to the new code style 
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
2023-01-11 14:50:10 +01:00

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/*
* Public Key layer for writing key files and structures
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "common.h"
#if defined(MBEDTLS_PK_WRITE_C)
#include "mbedtls/pk.h"
#include "mbedtls/asn1write.h"
#include "mbedtls/oid.h"
#include "mbedtls/platform_util.h"
#include "mbedtls/error.h"
#include <string.h>
#if defined(MBEDTLS_RSA_C)
#include "mbedtls/rsa.h"
#endif
#if defined(MBEDTLS_ECP_C)
#include "mbedtls/bignum.h"
#include "mbedtls/ecp.h"
#include "mbedtls/platform_util.h"
#endif
#if defined(MBEDTLS_RSA_C) || defined(MBEDTLS_ECP_C)
#include "pkwrite.h"
#endif
#if defined(MBEDTLS_ECDSA_C)
#include "mbedtls/ecdsa.h"
#endif
#if defined(MBEDTLS_PEM_WRITE_C)
#include "mbedtls/pem.h"
#endif
#if defined(MBEDTLS_USE_PSA_CRYPTO)
#include "psa/crypto.h"
#include "mbedtls/psa_util.h"
#endif
#include "mbedtls/platform.h"
#if defined(MBEDTLS_RSA_C)
/*
* RSAPublicKey ::= SEQUENCE {
* modulus INTEGER, -- n
* publicExponent INTEGER -- e
* }
*/
static int pk_write_rsa_pubkey(unsigned char **p, unsigned char *start,
mbedtls_rsa_context *rsa)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len = 0;
mbedtls_mpi T;
mbedtls_mpi_init(&T);
/* Export E */
if ((ret = mbedtls_rsa_export(rsa, NULL, NULL, NULL, NULL, &T)) != 0 ||
(ret = mbedtls_asn1_write_mpi(p, start, &T)) < 0) {
goto end_of_export;
}
len += ret;
/* Export N */
if ((ret = mbedtls_rsa_export(rsa, &T, NULL, NULL, NULL, NULL)) != 0 ||
(ret = mbedtls_asn1_write_mpi(p, start, &T)) < 0) {
goto end_of_export;
}
len += ret;
end_of_export:
mbedtls_mpi_free(&T);
if (ret < 0) {
return ret;
}
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SEQUENCE));
return (int) len;
}
#endif /* MBEDTLS_RSA_C */
#if defined(MBEDTLS_ECP_C)
/*
* EC public key is an EC point
*/
static int pk_write_ec_pubkey(unsigned char **p, unsigned char *start,
mbedtls_ecp_keypair *ec)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len = 0;
unsigned char buf[MBEDTLS_ECP_MAX_PT_LEN];
if ((ret = mbedtls_ecp_point_write_binary(&ec->grp, &ec->Q,
MBEDTLS_ECP_PF_UNCOMPRESSED,
&len, buf, sizeof(buf))) != 0) {
return ret;
}
if (*p < start || (size_t) (*p - start) < len) {
return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
}
*p -= len;
memcpy(*p, buf, len);
return (int) len;
}
/*
* ECParameters ::= CHOICE {
* namedCurve OBJECT IDENTIFIER
* }
*/
static int pk_write_ec_param(unsigned char **p, unsigned char *start,
mbedtls_ecp_keypair *ec)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len = 0;
const char *oid;
size_t oid_len;
if ((ret = mbedtls_oid_get_oid_by_ec_grp(ec->grp.id, &oid, &oid_len)) != 0) {
return ret;
}
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_oid(p, start, oid, oid_len));
return (int) len;
}
/*
* privateKey OCTET STRING -- always of length ceil(log2(n)/8)
*/
static int pk_write_ec_private(unsigned char **p, unsigned char *start,
mbedtls_ecp_keypair *ec)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t byte_length = (ec->grp.pbits + 7) / 8;
unsigned char tmp[MBEDTLS_ECP_MAX_BYTES];
ret = mbedtls_ecp_write_key(ec, tmp, byte_length);
if (ret != 0) {
goto exit;
}
ret = mbedtls_asn1_write_octet_string(p, start, tmp, byte_length);
exit:
mbedtls_platform_zeroize(tmp, byte_length);
return ret;
}
#endif /* MBEDTLS_ECP_C */
int mbedtls_pk_write_pubkey(unsigned char **p, unsigned char *start,
const mbedtls_pk_context *key)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len = 0;
#if defined(MBEDTLS_RSA_C)
if (mbedtls_pk_get_type(key) == MBEDTLS_PK_RSA) {
MBEDTLS_ASN1_CHK_ADD(len, pk_write_rsa_pubkey(p, start, mbedtls_pk_rsa(*key)));
} else
#endif
#if defined(MBEDTLS_ECP_C)
if (mbedtls_pk_get_type(key) == MBEDTLS_PK_ECKEY) {
MBEDTLS_ASN1_CHK_ADD(len, pk_write_ec_pubkey(p, start, mbedtls_pk_ec(*key)));
} else
#endif
#if defined(MBEDTLS_USE_PSA_CRYPTO)
if (mbedtls_pk_get_type(key) == MBEDTLS_PK_OPAQUE) {
size_t buffer_size;
mbedtls_svc_key_id_t *key_id = (mbedtls_svc_key_id_t *) key->pk_ctx;
if (*p < start) {
return MBEDTLS_ERR_PK_BAD_INPUT_DATA;
}
buffer_size = (size_t) (*p - start);
if (psa_export_public_key(*key_id, start, buffer_size, &len)
!= PSA_SUCCESS) {
return MBEDTLS_ERR_PK_BAD_INPUT_DATA;
} else {
*p -= len;
memmove(*p, start, len);
}
} else
#endif /* MBEDTLS_USE_PSA_CRYPTO */
return MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE;
return (int) len;
}
int mbedtls_pk_write_pubkey_der(const mbedtls_pk_context *key, unsigned char *buf, size_t size)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *c;
size_t len = 0, par_len = 0, oid_len;
mbedtls_pk_type_t pk_type;
const char *oid;
if (size == 0) {
return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
}
c = buf + size;
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_pk_write_pubkey(&c, buf, key));
if (c - buf < 1) {
return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
}
/*
* SubjectPublicKeyInfo ::= SEQUENCE {
* algorithm AlgorithmIdentifier,
* subjectPublicKey BIT STRING }
*/
*--c = 0;
len += 1;
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_BIT_STRING));
pk_type = mbedtls_pk_get_type(key);
#if defined(MBEDTLS_ECP_C)
if (pk_type == MBEDTLS_PK_ECKEY) {
MBEDTLS_ASN1_CHK_ADD(par_len, pk_write_ec_param(&c, buf, mbedtls_pk_ec(*key)));
}
#endif
#if defined(MBEDTLS_USE_PSA_CRYPTO)
if (pk_type == MBEDTLS_PK_OPAQUE) {
psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
psa_key_type_t key_type;
mbedtls_svc_key_id_t key_id;
psa_ecc_family_t curve;
size_t bits;
key_id = *((mbedtls_svc_key_id_t *) key->pk_ctx);
if (PSA_SUCCESS != psa_get_key_attributes(key_id, &attributes)) {
return MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED;
}
key_type = psa_get_key_type(&attributes);
bits = psa_get_key_bits(&attributes);
psa_reset_key_attributes(&attributes);
if (PSA_KEY_TYPE_IS_ECC_KEY_PAIR(key_type)) {
curve = PSA_KEY_TYPE_ECC_GET_FAMILY(key_type);
if (curve == 0) {
return MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE;
}
ret = mbedtls_psa_get_ecc_oid_from_id(curve, bits,
&oid, &oid_len);
if (ret != 0) {
return MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE;
}
/* Write EC algorithm parameters; that's akin
* to pk_write_ec_param() above. */
MBEDTLS_ASN1_CHK_ADD(par_len, mbedtls_asn1_write_oid(&c, buf,
oid,
oid_len));
/* The rest of the function works as for legacy EC contexts. */
pk_type = MBEDTLS_PK_ECKEY;
} else if (PSA_KEY_TYPE_IS_RSA(key_type)) {
/* The rest of the function works as for legacy RSA contexts. */
pk_type = MBEDTLS_PK_RSA;
} else {
return MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE;
}
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
if ((ret = mbedtls_oid_get_oid_by_pk_alg(pk_type, &oid,
&oid_len)) != 0) {
return ret;
}
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_algorithm_identifier(&c, buf, oid, oid_len,
par_len));
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SEQUENCE));
return (int) len;
}
int mbedtls_pk_write_key_der(const mbedtls_pk_context *key, unsigned char *buf, size_t size)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *c;
size_t len = 0;
if (size == 0) {
return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
}
c = buf + size;
#if defined(MBEDTLS_RSA_C)
if (mbedtls_pk_get_type(key) == MBEDTLS_PK_RSA) {
mbedtls_mpi T; /* Temporary holding the exported parameters */
mbedtls_rsa_context *rsa = mbedtls_pk_rsa(*key);
/*
* Export the parameters one after another to avoid simultaneous copies.
*/
mbedtls_mpi_init(&T);
/* Export QP */
if ((ret = mbedtls_rsa_export_crt(rsa, NULL, NULL, &T)) != 0 ||
(ret = mbedtls_asn1_write_mpi(&c, buf, &T)) < 0) {
goto end_of_export;
}
len += ret;
/* Export DQ */
if ((ret = mbedtls_rsa_export_crt(rsa, NULL, &T, NULL)) != 0 ||
(ret = mbedtls_asn1_write_mpi(&c, buf, &T)) < 0) {
goto end_of_export;
}
len += ret;
/* Export DP */
if ((ret = mbedtls_rsa_export_crt(rsa, &T, NULL, NULL)) != 0 ||
(ret = mbedtls_asn1_write_mpi(&c, buf, &T)) < 0) {
goto end_of_export;
}
len += ret;
/* Export Q */
if ((ret = mbedtls_rsa_export(rsa, NULL, NULL,
&T, NULL, NULL)) != 0 ||
(ret = mbedtls_asn1_write_mpi(&c, buf, &T)) < 0) {
goto end_of_export;
}
len += ret;
/* Export P */
if ((ret = mbedtls_rsa_export(rsa, NULL, &T,
NULL, NULL, NULL)) != 0 ||
(ret = mbedtls_asn1_write_mpi(&c, buf, &T)) < 0) {
goto end_of_export;
}
len += ret;
/* Export D */
if ((ret = mbedtls_rsa_export(rsa, NULL, NULL,
NULL, &T, NULL)) != 0 ||
(ret = mbedtls_asn1_write_mpi(&c, buf, &T)) < 0) {
goto end_of_export;
}
len += ret;
/* Export E */
if ((ret = mbedtls_rsa_export(rsa, NULL, NULL,
NULL, NULL, &T)) != 0 ||
(ret = mbedtls_asn1_write_mpi(&c, buf, &T)) < 0) {
goto end_of_export;
}
len += ret;
/* Export N */
if ((ret = mbedtls_rsa_export(rsa, &T, NULL,
NULL, NULL, NULL)) != 0 ||
(ret = mbedtls_asn1_write_mpi(&c, buf, &T)) < 0) {
goto end_of_export;
}
len += ret;
end_of_export:
mbedtls_mpi_free(&T);
if (ret < 0) {
return ret;
}
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_int(&c, buf, 0));
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c,
buf, MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SEQUENCE));
} else
#endif /* MBEDTLS_RSA_C */
#if defined(MBEDTLS_ECP_C)
if (mbedtls_pk_get_type(key) == MBEDTLS_PK_ECKEY) {
mbedtls_ecp_keypair *ec = mbedtls_pk_ec(*key);
size_t pub_len = 0, par_len = 0;
/*
* RFC 5915, or SEC1 Appendix C.4
*
* ECPrivateKey ::= SEQUENCE {
* version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
* privateKey OCTET STRING,
* parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
* publicKey [1] BIT STRING OPTIONAL
* }
*/
/* publicKey */
MBEDTLS_ASN1_CHK_ADD(pub_len, pk_write_ec_pubkey(&c, buf, ec));
if (c - buf < 1) {
return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
}
*--c = 0;
pub_len += 1;
MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_asn1_write_len(&c, buf, pub_len));
MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_BIT_STRING));
MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_asn1_write_len(&c, buf, pub_len));
MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_asn1_write_tag(&c, buf,
MBEDTLS_ASN1_CONTEXT_SPECIFIC |
MBEDTLS_ASN1_CONSTRUCTED | 1));
len += pub_len;
/* parameters */
MBEDTLS_ASN1_CHK_ADD(par_len, pk_write_ec_param(&c, buf, ec));
MBEDTLS_ASN1_CHK_ADD(par_len, mbedtls_asn1_write_len(&c, buf, par_len));
MBEDTLS_ASN1_CHK_ADD(par_len, mbedtls_asn1_write_tag(&c, buf,
MBEDTLS_ASN1_CONTEXT_SPECIFIC |
MBEDTLS_ASN1_CONSTRUCTED | 0));
len += par_len;
/* privateKey */
MBEDTLS_ASN1_CHK_ADD(len, pk_write_ec_private(&c, buf, ec));
/* version */
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_int(&c, buf, 1));
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SEQUENCE));
} else
#endif /* MBEDTLS_ECP_C */
return MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE;
return (int) len;
}
#if defined(MBEDTLS_PEM_WRITE_C)
#define PEM_BEGIN_PUBLIC_KEY "-----BEGIN PUBLIC KEY-----\n"
#define PEM_END_PUBLIC_KEY "-----END PUBLIC KEY-----\n"
#define PEM_BEGIN_PRIVATE_KEY_RSA "-----BEGIN RSA PRIVATE KEY-----\n"
#define PEM_END_PRIVATE_KEY_RSA "-----END RSA PRIVATE KEY-----\n"
#define PEM_BEGIN_PRIVATE_KEY_EC "-----BEGIN EC PRIVATE KEY-----\n"
#define PEM_END_PRIVATE_KEY_EC "-----END EC PRIVATE KEY-----\n"
#define PUB_DER_MAX_BYTES \
(MBEDTLS_PK_RSA_PUB_DER_MAX_BYTES > MBEDTLS_PK_ECP_PUB_DER_MAX_BYTES ? \
MBEDTLS_PK_RSA_PUB_DER_MAX_BYTES : MBEDTLS_PK_ECP_PUB_DER_MAX_BYTES)
#define PRV_DER_MAX_BYTES \
(MBEDTLS_PK_RSA_PRV_DER_MAX_BYTES > MBEDTLS_PK_ECP_PRV_DER_MAX_BYTES ? \
MBEDTLS_PK_RSA_PRV_DER_MAX_BYTES : MBEDTLS_PK_ECP_PRV_DER_MAX_BYTES)
int mbedtls_pk_write_pubkey_pem(const mbedtls_pk_context *key, unsigned char *buf, size_t size)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char output_buf[PUB_DER_MAX_BYTES];
size_t olen = 0;
if ((ret = mbedtls_pk_write_pubkey_der(key, output_buf,
sizeof(output_buf))) < 0) {
return ret;
}
if ((ret = mbedtls_pem_write_buffer(PEM_BEGIN_PUBLIC_KEY, PEM_END_PUBLIC_KEY,
output_buf + sizeof(output_buf) - ret,
ret, buf, size, &olen)) != 0) {
return ret;
}
return 0;
}
int mbedtls_pk_write_key_pem(const mbedtls_pk_context *key, unsigned char *buf, size_t size)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char output_buf[PRV_DER_MAX_BYTES];
const char *begin, *end;
size_t olen = 0;
if ((ret = mbedtls_pk_write_key_der(key, output_buf, sizeof(output_buf))) < 0) {
return ret;
}
#if defined(MBEDTLS_RSA_C)
if (mbedtls_pk_get_type(key) == MBEDTLS_PK_RSA) {
begin = PEM_BEGIN_PRIVATE_KEY_RSA;
end = PEM_END_PRIVATE_KEY_RSA;
} else
#endif
#if defined(MBEDTLS_ECP_C)
if (mbedtls_pk_get_type(key) == MBEDTLS_PK_ECKEY) {
begin = PEM_BEGIN_PRIVATE_KEY_EC;
end = PEM_END_PRIVATE_KEY_EC;
} else
#endif
return MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE;
if ((ret = mbedtls_pem_write_buffer(begin, end,
output_buf + sizeof(output_buf) - ret,
ret, buf, size, &olen)) != 0) {
return ret;
}
return 0;
}
#endif /* MBEDTLS_PEM_WRITE_C */
#endif /* MBEDTLS_PK_WRITE_C */
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