yuzu-emu/mbedtls
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

mbedtls_ecp_write_key_ext(): new function

Browse source 
Same as mbedtls_ecp_write_key(), but doesn't require the caller to figure out
the length of the output and possibly distinguish between Weierstrass and
Montgomery curves.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine 2024-02-19 16:27:35 +01:00
parent 7f523bf9eb
commit e3fb4ccabf
5 changed files with 195 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
ChangeLog.d/ecp_write_key.txt Normal file
View file

@ -0,0 +1,4 @@
Features
* The new function mbedtls_ecp_write_key_ext() is similar to
mbedtls_ecp_write_key(), but can be used without separately calculating
the output length.

20
include/mbedtls/ecp.h
View file

@ -1370,6 +1370,26 @@ int mbedtls_ecp_read_key(mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
int mbedtls_ecp_write_key(mbedtls_ecp_keypair *key,
unsigned char *buf, size_t buflen);
/**
* \brief This function exports an elliptic curve private key.
*
* \param key The private key.
* \param olen On success, the length of the private key.
* This is always (`grp->nbits` + 7) / 8 bytes
* where `grp->nbits` is the private key size in bits.
* \param buf The output buffer for containing the binary representation
* of the key.
* \param buflen The total length of the buffer in bytes.
* #MBEDTLS_ECP_MAX_BYTES is always sufficient.
*
* \return \c 0 on success.
* \return #MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL if the \p key
* representation is larger than the available space in \p buf.
* \return Another negative error code on different kinds of failure.
*/
int mbedtls_ecp_write_key_ext(mbedtls_ecp_keypair *key,
size_t *olen, unsigned char *buf, size_t buflen);
/**
* \brief This function exports an elliptic curve public key.
*

32
library/ecp.c
View file

@ -3333,6 +3333,38 @@ cleanup:
return ret;
}
int mbedtls_ecp_write_key_ext(mbedtls_ecp_keypair *key,
size_t *olen, unsigned char *buf, size_t buflen)
{
size_t len = (key->grp.nbits + 7) / 8;
if (len > buflen) {
/* For robustness, ensure *olen <= buflen even on error. */
*olen = 0;
return MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL;
}
*olen = len;
/* Private key not set */
if (key->d.n == 0) {
return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
}
#if defined(MBEDTLS_ECP_MONTGOMERY_ENABLED)
if (mbedtls_ecp_get_type(&key->grp) == MBEDTLS_ECP_TYPE_MONTGOMERY) {
return mbedtls_mpi_write_binary_le(&key->d, buf, len);
}
#endif
#if defined(MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED)
if (mbedtls_ecp_get_type(&key->grp) == MBEDTLS_ECP_TYPE_SHORT_WEIERSTRASS) {
return mbedtls_mpi_write_binary(&key->d, buf, len);
}
#endif
/* Private key set but no recognized curve type? This shouldn't happen. */
return MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
}
/*
* Write a public key.
*/

103
tests/suites/test_suite_ecp.data
View file

@ -888,6 +888,109 @@ ECP write key: Curve448, mostly-0 key, output_size=55
depends_on:MBEDTLS_ECP_DP_CURVE448_ENABLED
ecp_write_key:MBEDTLS_ECP_DP_CURVE448:"0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000080":55:MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
ECP write key ext: secp256r1, nominal
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_SECP256R1:"f12a1320760270a83cbffd53f6031ef76a5d86c8a204f2c30ca9ebf51f0f0ea7":32:0
ECP write key ext: secp256r1, output longer by 1
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_SECP256R1:"f12a1320760270a83cbffd53f6031ef76a5d86c8a204f2c30ca9ebf51f0f0ea7":33:0
ECP write key ext: secp256r1, output short by 1
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_SECP256R1:"f12a1320760270a83cbffd53f6031ef76a5d86c8a204f2c30ca9ebf51f0f0ea7":31:MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
ECP write key ext: secp256r1, output_size=0
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_SECP256R1:"f12a1320760270a83cbffd53f6031ef76a5d86c8a204f2c30ca9ebf51f0f0ea7":0:MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
ECP write key ext: secp256r1, top byte = 0, output_size=32
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_SECP256R1:"00ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff":32:0
ECP write key ext: secp256r1, top byte = 0, output_size=31
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_SECP256R1:"00ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff":31:MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
ECP write key ext: secp256r1, top byte = 0, output_size=30
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_SECP256R1:"00ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff":30:MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
ECP write key ext: secp256r1, mostly-0 key, output_size=32
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_SECP256R1:"0000000000000000000000000000000000000000000000000000000000000001":32:0
ECP write key ext: secp256r1, mostly-0 key, output_size=1
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_SECP256R1:"0000000000000000000000000000000000000000000000000000000000000001":1:MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
ECP write key ext: secp256r1, private key not set
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_SECP256R1:"":32:MBEDTLS_ERR_ECP_BAD_INPUT_DATA
ECP write key ext: secp384r1, nominal
depends_on:MBEDTLS_ECP_DP_SECP384R1_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_SECP384R1:"d27335ea71664af244dd14e9fd1260715dfd8a7965571c48d709ee7a7962a156d706a90cbcb5df2986f05feadb9376f1":48:0
ECP write key ext: secp384r1, output longer by 1
depends_on:MBEDTLS_ECP_DP_SECP384R1_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_SECP384R1:"d27335ea71664af244dd14e9fd1260715dfd8a7965571c48d709ee7a7962a156d706a90cbcb5df2986f05feadb9376f1":49:0
ECP write key ext: secp384r1, output short by 1
depends_on:MBEDTLS_ECP_DP_SECP384R1_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_SECP384R1:"d27335ea71664af244dd14e9fd1260715dfd8a7965571c48d709ee7a7962a156d706a90cbcb5df2986f05feadb9376f1":47:MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
ECP write key ext: Curve25519, nominal
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_CURVE25519:"a046e36bf0527c9d3b16154b82465edd62144c0ac1fc5a18506a2244ba449a44":32:0
ECP write key ext: Curve25519, output longer by 1
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_CURVE25519:"a046e36bf0527c9d3b16154b82465edd62144c0ac1fc5a18506a2244ba449a44":33:0
ECP write key ext: Curve25519, output short by 1
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_CURVE25519:"a046e36bf0527c9d3b16154b82465edd62144c0ac1fc5a18506a2244ba449a44":31:MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
ECP write key ext: Curve25519, output_size=0
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_CURVE25519:"a046e36bf0527c9d3b16154b82465edd62144c0ac1fc5a18506a2244ba449a44":0:MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
ECP write key ext: Curve25519, mostly-0 key, output_size=32
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_CURVE25519:"0000000000000000000000000000000000000000000000000000000000000040":32:0
ECP write key ext: Curve25519, mostly-0 key, output_size=31
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_CURVE25519:"0000000000000000000000000000000000000000000000000000000000000040":31:MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
ECP write key ext: Curve25519, private key not set
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_CURVE25519:"":32:MBEDTLS_ERR_ECP_BAD_INPUT_DATA
ECP write key ext: Curve448, nominal
depends_on:MBEDTLS_ECP_DP_CURVE448_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_CURVE448:"3c262fddf9ec8e88495266fea19a34d28882acef045104d0d1aae121700a779c984c24f8cdd78fbff44943eba368f54b29259a4f1c600ad3":56:0
ECP write key ext: Curve448, output longer by 1
depends_on:MBEDTLS_ECP_DP_CURVE448_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_CURVE448:"3c262fddf9ec8e88495266fea19a34d28882acef045104d0d1aae121700a779c984c24f8cdd78fbff44943eba368f54b29259a4f1c600ad3":57:0
ECP write key ext: Curve448, output short by 1
depends_on:MBEDTLS_ECP_DP_CURVE448_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_CURVE448:"3c262fddf9ec8e88495266fea19a34d28882acef045104d0d1aae121700a779c984c24f8cdd78fbff44943eba368f54b29259a4f1c600ad3":55:MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
ECP write key ext: Curve448, mostly-0 key, output_size=56
depends_on:MBEDTLS_ECP_DP_CURVE448_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_CURVE448:"0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000080":56:0
ECP write key ext: Curve448, mostly-0 key, output_size=55
depends_on:MBEDTLS_ECP_DP_CURVE448_ENABLED
ecp_write_key_ext:MBEDTLS_ECP_DP_CURVE448:"0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000080":55:MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL
ECP write key ext: group not set
ecp_write_key_ext:MBEDTLS_ECP_DP_NONE:"":32:MBEDTLS_ERR_ECP_BAD_INPUT_DATA
ECP mod p192 small (more than 192 bits, less limbs than 2 * 192 bits)
depends_on:MBEDTLS_ECP_DP_SECP192R1_ENABLED:MBEDTLS_ECP_NIST_OPTIM
ecp_fast_mod:MBEDTLS_ECP_DP_SECP192R1:"0100000000000103010000000000010201000000000001010100000000000100"

36
tests/suites/test_suite_ecp.function
View file

@ -1296,6 +1296,42 @@ exit:
}
/* END_CASE */
/* BEGIN_CASE */
void ecp_write_key_ext(int grp_id, data_t *in_key,
int exported_size, int expected_ret)
{
mbedtls_ecp_keypair key;
mbedtls_ecp_keypair_init(&key);
unsigned char *exported = NULL;
if (in_key->len != 0) {
TEST_EQUAL(mbedtls_ecp_read_key(grp_id, &key, in_key->x, in_key->len), 0);
} else if (grp_id != MBEDTLS_ECP_DP_NONE) {
TEST_EQUAL(mbedtls_ecp_group_load(&key.grp, grp_id), 0);
}
TEST_CALLOC(exported, exported_size);
size_t olen = 0xdeadbeef;
TEST_EQUAL(mbedtls_ecp_write_key_ext(&key, &olen, exported, exported_size),
expected_ret);
if (expected_ret == 0) {
TEST_EQUAL(olen, (key.grp.nbits + 7) / 8);
TEST_LE_U(olen, MBEDTLS_ECP_MAX_BYTES);
TEST_MEMORY_COMPARE(in_key->x, in_key->len,
exported, olen);
} else {
/* Robustness check: even in the error case, insist that olen is less
* than the buffer size. */
TEST_LE_U(olen, exported_size);
}
exit:
mbedtls_ecp_keypair_free(&key);
mbedtls_free(exported);
}
/* END_CASE */
/* BEGIN_CASE depends_on:MBEDTLS_TEST_HOOKS:MBEDTLS_ECP_MONTGOMERY_ENABLED:MBEDTLS_ECP_LIGHT */
void genkey_mx_known_answer(int bits, data_t *seed, data_t *expected)
{