Improve & test legacy mbedtls_pkcs12_pbe
* Prevent pkcs12_pbe encryption when PKCS7 padding has been
disabled since this not part of the specs.
* Allow decryption when PKCS7 padding is disabled for legacy
reasons, However, invalid padding is not checked.
* Document new behaviour, known limitations and possible
security concerns.
* Add tests to check these scenarios. Test data has been
generated by the below code using OpenSSL as a reference:
#include <openssl/pkcs12.h>
#include <openssl/evp.h>
#include <openssl/des.h>
#include <openssl/asn1.h>
#include "crypto/asn1.h"
#include <string.h>
int main()
{
char pass[] = "\xBB\xBB\xBB\xBB\xBB\xBB\xBB\xBB\xBB";
unsigned char salt[] = "\xCC\xCC\xCC\xCC\xCC\xCC\xCC\xCC\xCC";
unsigned char plaintext[] = "\xAA\xAA\xAA\xAA\xAA\xAA\xAA\xAA";
unsigned char *ciphertext = NULL;
int iter = 10;
X509_ALGOR *alg = X509_ALGOR_new();
int ciphertext_len = 0;
int alg_nid = NID_pbe_WithSHA1And3_Key_TripleDES_CBC;
alg->parameter = ASN1_TYPE_new();
struct asn1_object_st * aobj;
PKCS5_pbe_set0_algor(alg, alg_nid, iter,
salt, sizeof(salt)-1);
aobj = alg->algorithm;
printf("\"30%.2X", 2 + aobj->length + alg->parameter->value.asn1_string->length);
printf("06%.2X", aobj->length);
for (int i = 0; i < aobj->length; i++) {
printf("%.2X", aobj->data[i]);
}
for (int i = 0; i < alg->parameter->value.asn1_string->length; i++) {
printf("%.2X", alg->parameter->value.asn1_string->data[i]);
}
printf("\":\"");
for (int i = 0; i < sizeof(pass)-1; i++) {
printf("%.2X", pass[i] & 0xFF);
}
printf("\":\"");
for (int i = 0; i < sizeof(plaintext)-1; i++) {
printf("%.2X", plaintext[i]);
}
printf("\":");
printf("0");
printf(":\"");
unsigned char * res = PKCS12_pbe_crypt(alg, pass, sizeof(pass)-1, plaintext, sizeof(plaintext)-1, &ciphertext, &ciphertext_len, 1);
if (res == NULL)
printf("Encryption failed!\n");
for (int i = 0; i < ciphertext_len; i++) {
printf("%.2X", res[i]);
}
printf("\"\n");
return 0;
}
Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
#
diff --git a/include/mbedtls/pkcs12.h b/include/mbedtls/pkcs12.h
index eb9e2d9..8d003b5 100644
--- a/include/mbedtls/pkcs12.h
+++ b/include/mbedtls/pkcs12.h
@@ -56,6 +56,21 @@
* \brief PKCS12 Password Based function (encryption / decryption)
* for cipher-based and mbedtls_md-based PBE's
*
+ * \note When encrypting, #MBEDTLS_CIPHER_PADDING_PKCS7 must
+ * be enabled at compile time.
+ *
+ * \warning When decrypting:
+ * - if #MBEDTLS_CIPHER_PADDING_PKCS7 is enabled at compile
+ * time, this function validates the CBC padding and returns
+ * #MBEDTLS_ERR_PKCS12_PASSWORD_MISMATCH if the padding is
+ * invalid. Note that this can help active adversaries
+ * attempting to brute-forcing the password. Note also that
+ * there is no guarantee that an invalid password will be
+ * detected (the chances of a valid padding with a random
+ * password are about 1/255).
+ * - if #MBEDTLS_CIPHER_PADDING_PKCS7 is disabled at compile
+ * time, this function does not validate the CBC padding.
+ *
* \param pbe_params an ASN1 buffer containing the pkcs-12 PbeParams structure
* \param mode either #MBEDTLS_PKCS12_PBE_ENCRYPT or
* #MBEDTLS_PKCS12_PBE_DECRYPT
@@ -66,7 +81,15 @@
* \param pwdlen length of the password (may be 0)
* \param input the input data
* \param len data length
- * \param output the output buffer
+ * \param output Output buffer.
+ * On success, it contains the encrypted or decrypted data,
+ * possibly followed by the CBC padding.
+ * On failure, the content is indeterminate.
+ * For decryption, there must be enough room for \p len
+ * bytes.
+ * For encryption, there must be enough room for
+ * \p len + 1 bytes, rounded up to the block size of
+ * the block cipher identified by \p pbe_params.
*
* \return 0 if successful, or a MBEDTLS_ERR_XXX code
*/
diff --git a/library/pkcs12.c b/library/pkcs12.c
index db31722..6d52305 100644
--- a/library/pkcs12.c
+++ b/library/pkcs12.c
@@ -171,6 +171,25 @@
goto exit;
}
+#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
+ /* PKCS12 uses CBC with PKCS7 padding */
+
+ mbedtls_cipher_padding_t padding = MBEDTLS_PADDING_PKCS7;
+#if !defined(MBEDTLS_CIPHER_PADDING_PKCS7)
+ /* For historical reasons, when decrypting, this function works when
+ * decrypting even when support for PKCS7 padding is disabled. In this
+ * case, it ignores the padding, and so will never report a
+ * password mismatch.
+ */
+ if (mode == MBEDTLS_PKCS12_PBE_DECRYPT) {
+ padding = MBEDTLS_PADDING_NONE;
+ }
+#endif
+ if ((ret = mbedtls_cipher_set_padding_mode(&cipher_ctx, padding)) != 0) {
+ goto exit;
+ }
+#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */
+
if ((ret =
mbedtls_cipher_set_iv(&cipher_ctx, iv,
mbedtls_cipher_info_get_iv_size(cipher_info))) != 0) {
diff --git a/tests/suites/test_suite_pkcs12.data b/tests/suites/test_suite_pkcs12.data
index d8e41fe..f47ca9a 100644
--- a/tests/suites/test_suite_pkcs12.data
+++ b/tests/suites/test_suite_pkcs12.data
@@ -33,3 +33,32 @@
PKCS#12 derive key: MD5: Valid password and salt
depends_on:MBEDTLS_MD_CAN_MD5
pkcs12_derive_key:MBEDTLS_MD_MD5:48:"0123456789abcdef":USE_GIVEN_INPUT:"0123456789abcdef":USE_GIVEN_INPUT:3:"46559deeee036836ab1b633ec620178d4c70eacf42f72a2ad7360c812efa09ca3d7567b489a109050345c2dc6a262995":0
+
+PBE Encrypt, pad = 7 (OK)
+depends_on:MBEDTLS_MD_CAN_SHA1:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:MBEDTLS_CIPHER_PADDING_PKCS7
+pkcs12_pbe_encrypt:"301C060A2A864886F70D010C0103300E0409CCCCCCCCCCCCCCCCCC02010A":"BBBBBBBBBBBBBBBBBB":"AAAAAAAAAAAAAAAAAA":0:"5F2C15056A36F3A78856E9E662DD27CB"
+
+PBE Encrypt, pad = 8 (OK)
+depends_on:MBEDTLS_MD_CAN_SHA1:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:MBEDTLS_CIPHER_PADDING_PKCS7
+pkcs12_pbe_encrypt:"301C060A2A864886F70D010C0103300E0409CCCCCCCCCCCCCCCCCC02010A":"BBBBBBBBBBBBBBBBBB":"AAAAAAAAAAAAAAAA":0:"5F2C15056A36F3A70F70A3D4EC4004A8"
+
+PBE Encrypt, pad = 8 (PKCS7 padding disabled)
+depends_on:MBEDTLS_MD_CAN_SHA1:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:!MBEDTLS_CIPHER_PADDING_PKCS7
+pkcs12_pbe_encrypt:"301C060A2A864886F70D010C0103300E0409CCCCCCCCCCCCCCCCCC02010A":"BBBBBBBBBBBBBBBBBB":"AAAAAAAAAAAAAAAA":MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE:""
+
+PBE Decrypt, pad = 7 (OK)
+depends_on:MBEDTLS_MD_CAN_SHA1:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:MBEDTLS_CIPHER_PADDING_PKCS7
+pkcs12_pbe_decrypt:"301C060A2A864886F70D010C0103300E0409CCCCCCCCCCCCCCCCCC02010A":"BBBBBBBBBBBBBBBBBB":"5F2C15056A36F3A78856E9E662DD27CB":0:"AAAAAAAAAAAAAAAAAA07070707070707"
+
+PBE Decrypt, pad = 8 (OK)
+depends_on:MBEDTLS_MD_CAN_SHA1:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:MBEDTLS_CIPHER_PADDING_PKCS7
+pkcs12_pbe_decrypt:"301C060A2A864886F70D010C0103300E0409CCCCCCCCCCCCCCCCCC02010A":"BBBBBBBBBBBBBBBBBB":"5F2C15056A36F3A70F70A3D4EC4004A8":0:"AAAAAAAAAAAAAAAA0808080808080808"
+
+
+PBE Decrypt, (Invalid padding & PKCS7 padding disabled)
+depends_on:MBEDTLS_MD_CAN_SHA1:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:!MBEDTLS_CIPHER_PADDING_PKCS7
+pkcs12_pbe_decrypt:"301C060A2A864886F70D010C0103300E0409CCCCCCCCCCCCCCCCCC02010A":"BBBBBBBBBBBBBBBBBB":"5F2C15056A36F3A79F2B90F1428110E2":0:"AAAAAAAAAAAAAAAAAA07070707070708"
+
+PBE Decrypt, (Invalid padding & PKCS7 padding enabled)
+depends_on:MBEDTLS_MD_CAN_SHA1:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:MBEDTLS_CIPHER_PADDING_PKCS7
+pkcs12_pbe_decrypt:"301C060A2A864886F70D010C0103300E0409CCCCCCCCCCCCCCCCCC02010A":"BBBBBBBBBBBBBBBBBB":"5F2C15056A36F3A79F2B90F1428110E2":MBEDTLS_ERR_PKCS12_PASSWORD_MISMATCH:"AAAAAAAAAAAAAAAAAA07070707070708"
\ No newline at end of file
diff --git a/tests/suites/test_suite_pkcs12.function b/tests/suites/test_suite_pkcs12.function
index 2c93c13..8e5ab30 100644
--- a/tests/suites/test_suite_pkcs12.function
+++ b/tests/suites/test_suite_pkcs12.function
@@ -1,5 +1,6 @@
/* BEGIN_HEADER */
#include "mbedtls/pkcs12.h"
+#include "mbedtls/oid.h"
#include "common.h"
typedef enum {
@@ -14,7 +15,7 @@
* END_DEPENDENCIES
*/
-/* BEGIN_CASE */
+/* BEGIN_CASE MBEDTLS_ASN1_PARSE_C*/
void pkcs12_derive_key(int md_type, int key_size_arg,
data_t *password_arg, int password_usage,
data_t *salt_arg, int salt_usage,
@@ -44,7 +45,7 @@
salt_len = salt_arg->len;
- TEST_CALLOC(output_data, key_size);
+ ASSERT_ALLOC(output_data, key_size);
int ret = mbedtls_pkcs12_derivation(output_data,
key_size,
@@ -59,8 +60,8 @@
TEST_EQUAL(ret, expected_status);
if (expected_status == 0) {
- TEST_MEMORY_COMPARE(expected_output->x, expected_output->len,
- output_data, key_size);
+ ASSERT_COMPARE(expected_output->x, expected_output->len,
+ output_data, key_size);
}
exit:
@@ -68,3 +69,85 @@
MD_PSA_DONE();
}
/* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_ASN1_PARSE_C */
+void pkcs12_pbe_encrypt(data_t *params_hex, data_t *pw,
+ data_t *data, int ref_ret, data_t *ref_out)
+{
+ int my_ret;
+ mbedtls_asn1_buf pbe_alg_oid, pbe_params;
+ unsigned char *my_out = NULL;
+ unsigned char *p, *end;
+ mbedtls_cipher_type_t cipher_alg;
+ mbedtls_md_type_t md_alg;
+
+ MD_PSA_INIT();
+
+ p = params_hex->x;
+ end = p + params_hex->len;
+
+ my_ret = mbedtls_asn1_get_alg(&p, end, &pbe_alg_oid, &pbe_params);
+ if (my_ret) {
+ TEST_FAIL("Invalid test paramaters");
+ }
+ my_ret = mbedtls_oid_get_pkcs12_pbe_alg(&pbe_alg_oid, &md_alg, &cipher_alg);
+ if (my_ret) {
+ TEST_FAIL("Invalid test paramaters");
+ }
+
+ ASSERT_ALLOC(my_out, ref_out->len);
+
+ my_ret = mbedtls_pkcs12_pbe(&pbe_params, MBEDTLS_PKCS12_PBE_ENCRYPT, cipher_alg,
+ md_alg, pw->x, pw->len, data->x, data->len, my_out);
+ TEST_EQUAL(my_ret, ref_ret);
+ if (ref_ret == 0) {
+ ASSERT_COMPARE(my_out, ref_out->len,
+ ref_out->x, ref_out->len);
+ }
+
+exit:
+ mbedtls_free(my_out);
+ MD_PSA_DONE();
+}
+/* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_ASN1_PARSE_C */
+void pkcs12_pbe_decrypt(data_t *params_hex, data_t *pw,
+ data_t *data, int ref_ret, data_t *ref_out)
+{
+ int my_ret;
+ mbedtls_asn1_buf pbe_alg_oid, pbe_params;
+ unsigned char *my_out = NULL;
+ unsigned char *p, *end;
+ mbedtls_cipher_type_t cipher_alg;
+ mbedtls_md_type_t md_alg;
+
+ MD_PSA_INIT();
+
+ p = params_hex->x;
+ end = p + params_hex->len;
+
+ my_ret = mbedtls_asn1_get_alg(&p, end, &pbe_alg_oid, &pbe_params);
+ if (my_ret) {
+ TEST_FAIL("Invalid test paramaters");
+ }
+ my_ret = mbedtls_oid_get_pkcs12_pbe_alg(&pbe_alg_oid, &md_alg, &cipher_alg);
+ if (my_ret) {
+ TEST_FAIL("Invalid test paramaters");
+ }
+
+ ASSERT_ALLOC(my_out, ref_out->len);
+
+ my_ret = mbedtls_pkcs12_pbe(&pbe_params, MBEDTLS_PKCS12_PBE_DECRYPT, cipher_alg,
+ md_alg, pw->x, pw->len, data->x, data->len, my_out);
+ TEST_EQUAL(my_ret, ref_ret);
+ if (ref_ret == 0) {
+ ASSERT_COMPARE(my_out, ref_out->len,
+ ref_out->x, ref_out->len);
+ }
+
+exit:
+ mbedtls_free(my_out);
+ MD_PSA_DONE();
+}
+/* END_CASE */