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[crypto] Construct asymmetric ciphered data using ASN.1 builders

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Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2025-12-02 13:12:25 +00:00
parent d4258272c6
commit 1ccc320ee9
7 changed files with 156 additions and 129 deletions
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24
src/crypto/cms.c
View File

@@ -917,29 +917,26 @@ static int cms_cipher_key ( struct cms_message *cms,
struct pubkey_algorithm *pubkey = part->pubkey;
const struct asn1_cursor *key = privkey_cursor ( private_key );
const struct asn1_cursor *value = &part->value;
size_t max_len = pubkey_max_len ( pubkey, key );
uint8_t cipher_key[max_len];
int len;
struct asn1_builder cipher_key = { NULL, 0 };
int rc;
/* Decrypt cipher key */
len = pubkey_decrypt ( pubkey, key, value->data, value->len,
cipher_key );
if ( len < 0 ) {
rc = len;
if ( ( rc = pubkey_decrypt ( pubkey, key, value,
&cipher_key ) ) != 0 ) {
DBGC ( cms, "CMS %p/%p could not decrypt cipher key: %s\n",
cms, part, strerror ( rc ) );
DBGC_HDA ( cms, 0, value->data, value->len );
return rc;
goto err_decrypt;
}
DBGC ( cms, "CMS %p/%p cipher key:\n", cms, part );
DBGC_HDA ( cms, 0, cipher_key, len );
DBGC_HDA ( cms, 0, cipher_key.data, cipher_key.len );
/* Set cipher key */
if ( ( rc = cipher_setkey ( cipher, ctx, cipher_key, len ) ) != 0 ) {
if ( ( rc = cipher_setkey ( cipher, ctx, cipher_key.data,
cipher_key.len ) ) != 0 ) {
DBGC ( cms, "CMS %p could not set cipher key: %s\n",
cms, strerror ( rc ) );
return rc;
goto err_setkey;
}
/* Set cipher initialization vector */
@@ -949,7 +946,10 @@ static int cms_cipher_key ( struct cms_message *cms,
DBGC_HDA ( cms, 0, cms->iv.data, cms->iv.len );
}
return 0;
err_setkey:
err_decrypt:
free ( cipher_key.data );
return rc;
}
/**

10
src/crypto/crypto_null.c
View File

@@ -98,16 +98,14 @@ size_t pubkey_null_max_len ( const struct asn1_cursor *key __unused ) {
}
int pubkey_null_encrypt ( const struct asn1_cursor *key __unused,
const void *plaintext __unused,
size_t plaintext_len __unused,
void *ciphertext __unused ) {
const struct asn1_cursor *plaintext __unused,
struct asn1_builder *ciphertext __unused ) {
return 0;
}
int pubkey_null_decrypt ( const struct asn1_cursor *key __unused,
const void *ciphertext __unused,
size_t ciphertext_len __unused,
void *plaintext __unused ) {
const struct asn1_cursor *ciphertext __unused,
struct asn1_builder *plaintext __unused ) {
return 0;
}

65
src/crypto/rsa.c
View File

@@ -338,12 +338,12 @@ static void rsa_cipher ( struct rsa_context *context,
*
* @v key Key
* @v plaintext Plaintext
* @v plaintext_len Length of plaintext
* @v ciphertext Ciphertext
* @ret ciphertext_len Length of ciphertext, or negative error
*/
static int rsa_encrypt ( const struct asn1_cursor *key, const void *plaintext,
size_t plaintext_len, void *ciphertext ) {
static int rsa_encrypt ( const struct asn1_cursor *key,
const struct asn1_cursor *plaintext,
struct asn1_builder *ciphertext ) {
struct rsa_context context;
void *temp;
uint8_t *encoded;
@@ -352,7 +352,7 @@ static int rsa_encrypt ( const struct asn1_cursor *key, const void *plaintext,
int rc;
DBGC ( &context, "RSA %p encrypting:\n", &context );
DBGC_HDA ( &context, 0, plaintext, plaintext_len );
DBGC_HDA ( &context, 0, plaintext->data, plaintext->len );
/* Initialise context */
if ( ( rc = rsa_init ( &context, key ) ) != 0 )
@@ -360,12 +360,12 @@ static int rsa_encrypt ( const struct asn1_cursor *key, const void *plaintext,
/* Calculate lengths */
max_len = ( context.max_len - 11 );
random_nz_len = ( max_len - plaintext_len + 8 );
random_nz_len = ( max_len - plaintext->len + 8 );
/* Sanity check */
if ( plaintext_len > max_len ) {
if ( plaintext->len > max_len ) {
DBGC ( &context, "RSA %p plaintext too long (%zd bytes, max "
"%zd)\n", &context, plaintext_len, max_len );
"%zd)\n", &context, plaintext->len, max_len );
rc = -ERANGE;
goto err_sanity;
}
@@ -383,19 +383,24 @@ static int rsa_encrypt ( const struct asn1_cursor *key, const void *plaintext,
goto err_random;
}
encoded[ 2 + random_nz_len ] = 0x00;
memcpy ( &encoded[ context.max_len - plaintext_len ],
plaintext, plaintext_len );
memcpy ( &encoded[ context.max_len - plaintext->len ],
plaintext->data, plaintext->len );
/* Create space for ciphertext */
if ( ( rc = asn1_grow ( ciphertext, context.max_len ) ) != 0 )
goto err_grow;
/* Encipher the encoded message */
rsa_cipher ( &context, encoded, ciphertext );
rsa_cipher ( &context, encoded, ciphertext->data );
DBGC ( &context, "RSA %p encrypted:\n", &context );
DBGC_HDA ( &context, 0, ciphertext, context.max_len );
DBGC_HDA ( &context, 0, ciphertext->data, context.max_len );
/* Free context */
rsa_free ( &context );
return context.max_len;
return 0;
err_grow:
err_random:
err_sanity:
rsa_free ( &context );
@@ -408,33 +413,33 @@ static int rsa_encrypt ( const struct asn1_cursor *key, const void *plaintext,
*
* @v key Key
* @v ciphertext Ciphertext
* @v ciphertext_len Ciphertext length
* @v plaintext Plaintext
* @ret plaintext_len Plaintext length, or negative error
* @ret rc Return status code
*/
static int rsa_decrypt ( const struct asn1_cursor *key, const void *ciphertext,
size_t ciphertext_len, void *plaintext ) {
static int rsa_decrypt ( const struct asn1_cursor *key,
const struct asn1_cursor *ciphertext,
struct asn1_builder *plaintext ) {
struct rsa_context context;
void *temp;
uint8_t *encoded;
uint8_t *end;
uint8_t *zero;
uint8_t *start;
size_t plaintext_len;
size_t len;
int rc;
DBGC ( &context, "RSA %p decrypting:\n", &context );
DBGC_HDA ( &context, 0, ciphertext, ciphertext_len );
DBGC_HDA ( &context, 0, ciphertext->data, ciphertext->len );
/* Initialise context */
if ( ( rc = rsa_init ( &context, key ) ) != 0 )
goto err_init;
/* Sanity check */
if ( ciphertext_len != context.max_len ) {
if ( ciphertext->len != context.max_len ) {
DBGC ( &context, "RSA %p ciphertext incorrect length (%zd "
"bytes, should be %zd)\n",
&context, ciphertext_len, context.max_len );
&context, ciphertext->len, context.max_len );
rc = -ERANGE;
goto err_sanity;
}
@@ -444,7 +449,7 @@ static int rsa_decrypt ( const struct asn1_cursor *key, const void *ciphertext,
*/
temp = context.input0;
encoded = temp;
rsa_cipher ( &context, ciphertext, encoded );
rsa_cipher ( &context, ciphertext->data, encoded );
/* Parse the message */
end = ( encoded + context.max_len );
@@ -454,25 +459,31 @@ static int rsa_decrypt ( const struct asn1_cursor *key, const void *ciphertext,
}
zero = memchr ( &encoded[2], 0, ( end - &encoded[2] ) );
if ( ! zero ) {
DBGC ( &context, "RSA %p invalid decrypted message:\n",
&context );
DBGC_HDA ( &context, 0, encoded, context.max_len );
rc = -EINVAL;
goto err_invalid;
}
start = ( zero + 1 );
plaintext_len = ( end - start );
len = ( end - start );
/* Create space for plaintext */
if ( ( rc = asn1_grow ( plaintext, len ) ) != 0 )
goto err_grow;
/* Copy out message */
memcpy ( plaintext, start, plaintext_len );
memcpy ( plaintext->data, start, len );
DBGC ( &context, "RSA %p decrypted:\n", &context );
DBGC_HDA ( &context, 0, plaintext, plaintext_len );
DBGC_HDA ( &context, 0, plaintext->data, len );
/* Free context */
rsa_free ( &context );
return plaintext_len;
return 0;
err_grow:
err_invalid:
DBGC ( &context, "RSA %p invalid decrypted message:\n", &context );
DBGC_HDA ( &context, 0, encoded, context.max_len );
err_sanity:
rsa_free ( &context );
err_init:

34
src/include/ipxe/crypto.h
View File

@@ -131,22 +131,22 @@ struct pubkey_algorithm {
*
* @v key Key
* @v plaintext Plaintext
* @v plaintext_len Length of plaintext
* @v ciphertext Ciphertext
* @ret ciphertext_len Length of ciphertext, or negative error
* @ret rc Return status code
*/
int ( * encrypt ) ( const struct asn1_cursor *key, const void *data,
size_t len, void *out );
int ( * encrypt ) ( const struct asn1_cursor *key,
const struct asn1_cursor *plaintext,
struct asn1_builder *ciphertext );
/** Decrypt
*
* @v key Key
* @v ciphertext Ciphertext
* @v ciphertext_len Ciphertext length
* @v plaintext Plaintext
* @ret plaintext_len Plaintext length, or negative error
* @ret rc Return status code
*/
int ( * decrypt ) ( const struct asn1_cursor *key, const void *data,
size_t len, void *out );
int ( * decrypt ) ( const struct asn1_cursor *key,
const struct asn1_cursor *ciphertext,
struct asn1_builder *plaintext );
/** Sign digest value
*
* @v key Key
@@ -274,14 +274,16 @@ pubkey_max_len ( struct pubkey_algorithm *pubkey,
static inline __attribute__ (( always_inline )) int
pubkey_encrypt ( struct pubkey_algorithm *pubkey, const struct asn1_cursor *key,
const void *data, size_t len, void *out ) {
return pubkey->encrypt ( key, data, len, out );
const struct asn1_cursor *plaintext,
struct asn1_builder *ciphertext ) {
return pubkey->encrypt ( key, plaintext, ciphertext );
}
static inline __attribute__ (( always_inline )) int
pubkey_decrypt ( struct pubkey_algorithm *pubkey, const struct asn1_cursor *key,
const void *data, size_t len, void *out ) {
return pubkey->decrypt ( key, data, len, out );
const struct asn1_cursor *ciphertext,
struct asn1_builder *plaintext ) {
return pubkey->decrypt ( key, ciphertext, plaintext );
}
static inline __attribute__ (( always_inline )) int
@@ -325,11 +327,11 @@ extern void cipher_null_auth ( void *ctx, void *auth );
extern size_t pubkey_null_max_len ( const struct asn1_cursor *key );
extern int pubkey_null_encrypt ( const struct asn1_cursor *key,
const void *plaintext, size_t plaintext_len,
void *ciphertext );
const struct asn1_cursor *plaintext,
struct asn1_builder *ciphertext );
extern int pubkey_null_decrypt ( const struct asn1_cursor *key,
const void *ciphertext, size_t ciphertext_len,
void *plaintext );
const struct asn1_cursor *ciphertext,
struct asn1_builder *plaintext );
extern int pubkey_null_sign ( const struct asn1_cursor *key,
struct digest_algorithm *digest,
const void *value,

66
src/net/tls.c
View File

@@ -1416,59 +1416,69 @@ static int tls_send_certificate ( struct tls_connection *tls ) {
static int tls_send_client_key_exchange_pubkey ( struct tls_connection *tls ) {
struct tls_cipherspec *cipherspec = &tls->tx.cipherspec.pending;
struct pubkey_algorithm *pubkey = cipherspec->suite->pubkey;
size_t max_len = pubkey_max_len ( pubkey, &tls->server.key );
struct {
uint16_t version;
uint8_t random[46];
} __attribute__ (( packed )) pre_master_secret;
struct {
uint32_t type_length;
uint16_t encrypted_pre_master_secret_len;
uint8_t encrypted_pre_master_secret[max_len];
} __attribute__ (( packed )) key_xchg;
size_t unused;
int len;
struct asn1_cursor cursor = {
.data = &pre_master_secret,
.len = sizeof ( pre_master_secret ),
};
struct asn1_builder builder = { NULL, 0 };
int rc;
/* Generate pre-master secret */
pre_master_secret.version = htons ( TLS_VERSION_MAX );
if ( ( rc = tls_generate_random ( tls, &pre_master_secret.random,
( sizeof ( pre_master_secret.random ) ) ) ) != 0 ) {
return rc;
goto err_random;
}
/* Encrypt pre-master secret using server's public key */
memset ( &key_xchg, 0, sizeof ( key_xchg ) );
len = pubkey_encrypt ( pubkey, &tls->server.key, &pre_master_secret,
sizeof ( pre_master_secret ),
key_xchg.encrypted_pre_master_secret );
if ( len < 0 ) {
rc = len;
if ( ( rc = pubkey_encrypt ( pubkey, &tls->server.key, &cursor,
&builder ) ) != 0 ) {
DBGC ( tls, "TLS %p could not encrypt pre-master secret: %s\n",
tls, strerror ( rc ) );
return rc;
goto err_encrypt;
}
unused = ( max_len - len );
key_xchg.type_length =
/* Construct Client Key Exchange record */
{
struct {
uint32_t type_length;
uint16_t encrypted_pre_master_secret_len;
} __attribute__ (( packed )) header;
header.type_length =
( cpu_to_le32 ( TLS_CLIENT_KEY_EXCHANGE ) |
htonl ( sizeof ( key_xchg ) -
sizeof ( key_xchg.type_length ) - unused ) );
key_xchg.encrypted_pre_master_secret_len =
htons ( sizeof ( key_xchg.encrypted_pre_master_secret ) -
unused );
htonl ( builder.len + sizeof ( header ) -
sizeof ( header.type_length ) ) );
header.encrypted_pre_master_secret_len = htons ( builder.len );
if ( ( rc = asn1_prepend_raw ( &builder, &header,
sizeof ( header ) ) ) != 0 ) {
DBGC ( tls, "TLS %p could not construct Client Key "
"Exchange: %s\n", tls, strerror ( rc ) );
goto err_prepend;
}
}
/* Transmit Client Key Exchange record */
if ( ( rc = tls_send_handshake ( tls, &key_xchg,
( sizeof ( key_xchg ) -
unused ) ) ) != 0 ) {
return rc;
if ( ( rc = tls_send_handshake ( tls, builder.data,
builder.len ) ) != 0 ) {
goto err_send;
}
/* Generate master secret */
tls_generate_master_secret ( tls, &pre_master_secret,
sizeof ( pre_master_secret ) );
return 0;
err_random:
err_encrypt:
err_prepend:
err_send:
free ( builder.data );
return rc;
}
/** Public key exchange algorithm */

64
src/tests/pubkey_test.c
View File

@@ -50,41 +50,47 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
void pubkey_okx ( struct pubkey_test *test, const char *file,
unsigned int line ) {
struct pubkey_algorithm *pubkey = test->pubkey;
size_t max_len = pubkey_max_len ( pubkey, &test->private );
uint8_t encrypted[max_len];
uint8_t decrypted[max_len];
int encrypted_len;
int decrypted_len;
struct asn1_builder plaintext;
struct asn1_builder ciphertext;
/* Test decrypting with private key to obtain known plaintext */
decrypted_len = pubkey_decrypt ( pubkey, &test->private,
test->ciphertext, test->ciphertext_len,
decrypted );
okx ( decrypted_len == ( ( int ) test->plaintext_len ), file, line );
okx ( memcmp ( decrypted, test->plaintext, test->plaintext_len ) == 0,
file, line );
plaintext.data = NULL;
plaintext.len = 0;
okx ( pubkey_decrypt ( pubkey, &test->private, &test->ciphertext,
&plaintext ) == 0, file, line );
okx ( asn1_compare ( asn1_built ( &plaintext ),
&test->plaintext ) == 0, file, line );
free ( plaintext.data );
/* Test encrypting with private key and decrypting with public key */
encrypted_len = pubkey_encrypt ( pubkey, &test->private,
test->plaintext, test->plaintext_len,
encrypted );
okx ( encrypted_len >= 0, file, line );
decrypted_len = pubkey_decrypt ( pubkey, &test->public, encrypted,
encrypted_len, decrypted );
okx ( decrypted_len == ( ( int ) test->plaintext_len ), file, line );
okx ( memcmp ( decrypted, test->plaintext, test->plaintext_len ) == 0,
file, line );
ciphertext.data = NULL;
ciphertext.len = 0;
plaintext.data = NULL;
plaintext.len = 0;
okx ( pubkey_encrypt ( pubkey, &test->private, &test->plaintext,
&ciphertext ) == 0, file, line );
okx ( pubkey_decrypt ( pubkey, &test->public,
asn1_built ( &ciphertext ),
&plaintext ) == 0, file, line );
okx ( asn1_compare ( asn1_built ( &plaintext ),
&test->plaintext ) == 0, file, line );
free ( ciphertext.data );
free ( plaintext.data );
/* Test encrypting with public key and decrypting with private key */
encrypted_len = pubkey_encrypt ( pubkey, &test->public,
test->plaintext, test->plaintext_len,
encrypted );
okx ( encrypted_len >= 0, file, line );
decrypted_len = pubkey_decrypt ( pubkey, &test->private, encrypted,
encrypted_len, decrypted );
okx ( decrypted_len == ( ( int ) test->plaintext_len ), file, line );
okx ( memcmp ( decrypted, test->plaintext, test->plaintext_len ) == 0,
file, line );
ciphertext.data = NULL;
ciphertext.len = 0;
plaintext.data = NULL;
plaintext.len = 0;
okx ( pubkey_encrypt ( pubkey, &test->public, &test->plaintext,
&ciphertext ) == 0, file, line );
okx ( pubkey_decrypt ( pubkey, &test->private,
asn1_built ( &ciphertext ),
&plaintext ) == 0, file, line );
okx ( asn1_compare ( asn1_built ( &plaintext ),
&test->plaintext ) == 0, file, line );
free ( ciphertext.data );
free ( plaintext.data );
}
/**

20
src/tests/pubkey_test.h
View File

@@ -16,18 +16,14 @@ struct pubkey_test {
/** Public key */
const struct asn1_cursor public;
/** Plaintext */
const void *plaintext;
/** Length of plaintext */
size_t plaintext_len;
const struct asn1_cursor plaintext;
/** Ciphertext
*
* Note that the encryption process may include some random
* padding, so a given plaintext will encrypt to multiple
* different ciphertexts.
*/
const void *ciphertext;
/** Length of ciphertext */
size_t ciphertext_len;
const struct asn1_cursor ciphertext;
};
/** A public-key signature test */
@@ -90,10 +86,14 @@ struct pubkey_sign_test {
.data = name ## _public, \
.len = sizeof ( name ## _public ), \
}, \
.plaintext = name ## _plaintext, \
.plaintext_len = sizeof ( name ## _plaintext ), \
.ciphertext = name ## _ciphertext, \
.ciphertext_len = sizeof ( name ## _ciphertext ), \
.plaintext = { \
.data = name ## _plaintext, \
.len = sizeof ( name ## _plaintext ), \
}, \
.ciphertext = { \
.data = name ## _ciphertext, \
.len = sizeof ( name ## _ciphertext ), \
}, \
}
/**