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pk_wrap: rework and tidy up signature extraction

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Improve comments, use a normal buffer instead of mbedtls_asn1_buf,
remove unneeded variables and use shared utilities where possible.
This commit is contained in:
Andrzej Kurek 2018-11-20 05:04:35 -05:00
parent 688ea8d10d
commit 73bf6b9e00
1 changed files with 44 additions and 125 deletions
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169
library/pk_wrap.c
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@ -480,150 +480,70 @@ static int ecdsa_can_do( mbedtls_pk_type_t type )
#if defined(MBEDTLS_USE_PSA_CRYPTO) #if defined(MBEDTLS_USE_PSA_CRYPTO)
/* /*
* Extract one signature part of an ASN.1 integer type to a given buffer * An ASN.1 encoded signature is a sequence of two ASN.1 integers. Parse one of
* and adjust padding according to part_size. * those integers and convert it to the fixed-length encoding expected by PSA.
*/ */
static int extract_ecdsa_sig_part( unsigned char **from, const unsigned char *end, static int extract_ecdsa_sig_int( unsigned char **from, const unsigned char *end,
unsigned char *to, size_t part_size ) unsigned char *to, size_t to_len )
{ {
int ret; int ret;
size_t len_total, len_partial, zero_padding; size_t unpadded_len, padding_len;
if( ( ret = mbedtls_asn1_get_tag( from, end, &len_partial, if( ( ret = mbedtls_asn1_get_tag( from, end, &unpadded_len,
MBEDTLS_ASN1_INTEGER ) ) != 0 ) MBEDTLS_ASN1_INTEGER ) ) != 0 )
{ {
return( ret ); return( ret );
} }
while( **from == '\0' && len_partial > 0 ) while( unpadded_len > 0 && **from == 0x00 )
{ {
( *from )++; ( *from )++;
len_partial--; unpadded_len--;
} }
if( len_partial > part_size || len_partial == 0 ) if( unpadded_len > to_len || unpadded_len == 0 )
return( MBEDTLS_ERR_PK_SIG_LEN_MISMATCH ); return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
zero_padding = part_size - len_partial; padding_len = to_len - unpadded_len;
memcpy( to + zero_padding, *from, len_partial ); memcpy( to + padding_len, *from, unpadded_len );
len_total = len_partial + zero_padding; ( *from ) += unpadded_len;
while( zero_padding > 0 )
{
zero_padding--;
to[zero_padding] = 0;
}
( *from ) += len_partial; memset( to, 0x00, padding_len );
return len_total;
return( 0 );
} }
/* /*
* Convert a signature from an ASN.1 sequence of two integers * Convert a signature from an ASN.1 sequence of two integers
* to a raw {r,s} buffer. Note: the provided sig buffer should be at least * to a raw {r,s} buffer. Note: the provided sig buffer must be at least
* twice as big as int_size. * twice as big as int_size.
*/ */
static int extract_ecdsa_sig( unsigned char **p, const unsigned char *end, static int extract_ecdsa_sig( unsigned char **p, const unsigned char *end,
mbedtls_asn1_buf *sig, size_t int_size ) unsigned char *sig, size_t int_size )
{ {
int ret; int ret;
size_t tmp_size;
if( ( end - *p ) < 1 ) if( ( end - *p ) < 1 )
{ {
return( MBEDTLS_ERR_ASN1_OUT_OF_DATA ); return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
} }
if( sig->p == NULL ) if( sig == NULL )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
sig->tag = **p; if( ( ret = mbedtls_asn1_get_tag( p, end, &tmp_size,
if( ( ret = mbedtls_asn1_get_tag( p, end, &sig->len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 ) MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
{ return( ret );
goto cleanup;
}
/* Extract r */ /* Extract r */
if( ( ret = extract_ecdsa_sig_part( p, end, sig->p, int_size ) ) < 0) if( ( ret = extract_ecdsa_sig_int( p, end, sig, int_size ) ) != 0 )
{ return( ret );
goto cleanup; /* Extract s */
} if( ( ret = extract_ecdsa_sig_int( p, end, sig + int_size, int_size ) ) != 0 )
sig->len = ret;
/* Extract s */
if( ( ret = extract_ecdsa_sig_part( p, end, sig->p + sig->len, int_size ) ) < 0)
{
goto cleanup;
}
sig->len += ret;
return( 0 );
cleanup:
sig->len = 0;
sig->tag = 0;
return( ret ); return( ret );
}
static psa_ecc_curve_t mbedtls_ecc_group_to_psa( mbedtls_ecp_group_id grpid )
{
switch( grpid )
{
#if defined(MBEDTLS_ECP_DP_SECP192R1_ENABLED)
case MBEDTLS_ECP_DP_SECP192R1:
return( PSA_ECC_CURVE_SECP192R1 );
#endif
#if defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED)
case MBEDTLS_ECP_DP_SECP224R1:
return( PSA_ECC_CURVE_SECP224R1 );
#endif
#if defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED)
case MBEDTLS_ECP_DP_SECP256R1:
return( PSA_ECC_CURVE_SECP256R1 );
#endif
#if defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED)
case MBEDTLS_ECP_DP_SECP384R1:
return( PSA_ECC_CURVE_SECP384R1 );
#endif
#if defined(MBEDTLS_ECP_DP_SECP521R1_ENABLED)
case MBEDTLS_ECP_DP_SECP521R1:
return( PSA_ECC_CURVE_SECP521R1 );
#endif
#if defined(MBEDTLS_ECP_DP_BP256R1_ENABLED)
case MBEDTLS_ECP_DP_BP256R1:
return( PSA_ECC_CURVE_BRAINPOOL_P256R1 );
#endif
#if defined(MBEDTLS_ECP_DP_BP384R1_ENABLED)
case MBEDTLS_ECP_DP_BP384R1:
return( PSA_ECC_CURVE_BRAINPOOL_P384R1 );
#endif
#if defined(MBEDTLS_ECP_DP_BP512R1_ENABLED)
case MBEDTLS_ECP_DP_BP512R1:
return( PSA_ECC_CURVE_BRAINPOOL_P512R1 );
#endif
#if defined(MBEDTLS_ECP_DP_CURVE25519_ENABLED)
case MBEDTLS_ECP_DP_CURVE25519:
return( PSA_ECC_CURVE_CURVE25519 );
#endif
#if defined(MBEDTLS_ECP_DP_SECP192K1_ENABLED)
case MBEDTLS_ECP_DP_SECP192K1:
return( PSA_ECC_CURVE_SECP192K1 );
#endif
#if defined(MBEDTLS_ECP_DP_SECP224K1_ENABLED)
case MBEDTLS_ECP_DP_SECP224K1:
return( PSA_ECC_CURVE_SECP224K1 );
#endif
#if defined(MBEDTLS_ECP_DP_SECP256K1_ENABLED)
case MBEDTLS_ECP_DP_SECP256K1:
return( PSA_ECC_CURVE_SECP256K1 );
#endif
#if defined(MBEDTLS_ECP_DP_CURVE448_ENABLED)
case MBEDTLS_ECP_DP_CURVE448:
return( PSA_ECC_CURVE_CURVE448 );
#endif
default:
return( 0 ); return( 0 );
}
} }
static int ecdsa_verify_wrap( void *ctx, mbedtls_md_type_t md_alg, static int ecdsa_verify_wrap( void *ctx, mbedtls_md_type_t md_alg,
@ -635,36 +555,36 @@ static int ecdsa_verify_wrap( void *ctx, mbedtls_md_type_t md_alg,
psa_key_policy_t policy; psa_key_policy_t policy;
psa_key_type_t psa_type; psa_key_type_t psa_type;
mbedtls_pk_context key; mbedtls_pk_context key;
mbedtls_asn1_buf signature;
int key_len; int key_len;
const unsigned buf_len = 30 + 2 * MBEDTLS_ECP_MAX_BYTES; // Equivalent of ECP_PUB_DER_MAX_BYTES /* see ECP_PUB_DER_MAX_BYTES in pkwrite.c */
unsigned char buf[buf_len]; unsigned char buf[30 + 2 * MBEDTLS_ECP_MAX_BYTES];
unsigned char *p = (unsigned char*) sig; unsigned char *p = (unsigned char*) sig;
mbedtls_pk_info_t pk_info = mbedtls_eckey_info; mbedtls_pk_info_t pk_info = mbedtls_eckey_info;
psa_algorithm_t psa_sig_md = mbedtls_psa_translate_md( md_alg ); psa_algorithm_t psa_sig_md, psa_md;
psa_ecc_curve_t curve = mbedtls_ecc_group_to_psa ( ( (mbedtls_ecdsa_context *) ctx )->grp.id ); psa_ecc_curve_t curve = mbedtls_psa_translate_ecc_group (
( (mbedtls_ecdsa_context *) ctx )->grp.id );
size_t signature_part_size = ( ( (mbedtls_ecdsa_context *) ctx ) ->grp.nbits + 7 ) / 8; size_t signature_part_size = ( ( (mbedtls_ecdsa_context *) ctx ) ->grp.nbits + 7 ) / 8;
if( curve == 0 ) if( curve == 0 )
return( MBEDTLS_ERR_PK_BAD_INPUT_DATA ); return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
if( psa_sig_md == 0 ) /* mbedlts_pk_write_pubkey_der() expects a full PK context,
return( MBEDTLS_ERR_PK_BAD_INPUT_DATA ); * re-construct one to make it happy */
psa_sig_md = PSA_ALG_ECDSA( psa_sig_md );
memset( &signature, 0, sizeof( mbedtls_asn1_buf ) );
key.pk_info = &pk_info; key.pk_info = &pk_info;
key.pk_ctx = ctx; key.pk_ctx = ctx;
key_len = mbedtls_pk_write_pubkey_der( &key, buf, sizeof( buf ) );
psa_type = PSA_KEY_TYPE_ECC_PUBLIC_KEY( curve );
key_len = mbedtls_pk_write_pubkey_der( &key, buf, buf_len );
if( key_len <= 0 ) if( key_len <= 0 )
return( MBEDTLS_ERR_PK_BAD_INPUT_DATA ); return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
if( ( ret = mbedtls_psa_get_free_key_slot( &key_slot ) ) != PSA_SUCCESS ) if( ( ret = mbedtls_psa_get_free_key_slot( &key_slot ) ) != PSA_SUCCESS )
return( mbedtls_psa_err_translate_pk( ret ) ); return( mbedtls_psa_err_translate_pk( ret ) );
psa_md = mbedtls_psa_translate_md( md_alg );
if( psa_md == 0 )
return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
psa_sig_md = PSA_ALG_ECDSA( psa_md );
psa_type = PSA_KEY_TYPE_ECC_PUBLIC_KEY( curve );
psa_key_policy_init( &policy ); psa_key_policy_init( &policy );
psa_key_policy_set_usage( &policy, PSA_KEY_USAGE_VERIFY, psa_sig_md ); psa_key_policy_set_usage( &policy, PSA_KEY_USAGE_VERIFY, psa_sig_md );
if( ( ret = psa_set_key_policy( key_slot, &policy ) ) != PSA_SUCCESS ) if( ( ret = psa_set_key_policy( key_slot, &policy ) ) != PSA_SUCCESS )
@ -673,7 +593,7 @@ static int ecdsa_verify_wrap( void *ctx, mbedtls_md_type_t md_alg,
goto cleanup; goto cleanup;
} }
if( psa_import_key( key_slot, psa_type, buf+buf_len-key_len, key_len ) if( psa_import_key( key_slot, psa_type, buf + sizeof( buf ) - key_len, key_len )
!= PSA_SUCCESS ) != PSA_SUCCESS )
{ {
ret = MBEDTLS_ERR_PK_BAD_INPUT_DATA; ret = MBEDTLS_ERR_PK_BAD_INPUT_DATA;
@ -681,14 +601,13 @@ static int ecdsa_verify_wrap( void *ctx, mbedtls_md_type_t md_alg,
} }
/* Reuse the buffer of an already imported key */ /* Reuse the buffer of an already imported key */
if( 2 * signature_part_size > buf_len ) if( 2 * signature_part_size > sizeof( buf ) )
{ {
ret = MBEDTLS_ERR_PK_BAD_INPUT_DATA; ret = MBEDTLS_ERR_PK_BAD_INPUT_DATA;
goto cleanup; goto cleanup;
} }
signature.p = buf;
if( ( ret = extract_ecdsa_sig( &p, p + sig_len, &signature, if( ( ret = extract_ecdsa_sig( &p, p + sig_len, buf,
signature_part_size ) ) != 0 ) signature_part_size ) ) != 0 )
{ {
goto cleanup; goto cleanup;
@ -696,7 +615,7 @@ static int ecdsa_verify_wrap( void *ctx, mbedtls_md_type_t md_alg,
if( psa_asymmetric_verify( key_slot, psa_sig_md, if( psa_asymmetric_verify( key_slot, psa_sig_md,
hash, hash_len, hash, hash_len,
signature.p, signature.len ) buf, 2 * signature_part_size )
!= PSA_SUCCESS ) != PSA_SUCCESS )
{ {
ret = MBEDTLS_ERR_ECP_VERIFY_FAILED; ret = MBEDTLS_ERR_ECP_VERIFY_FAILED;