[RFC 7/8] cert: add explicit length to l_cert_pkcs5_pbkdf2

Rather than assume the password/key is a NULL terminated string pass
the length in too. This is more flexible in case of a binary key.
---
 ell/cert-crypto.c | 7 ++++---
 ell/cert.h        | 1 +
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/ell/cert-crypto.c b/ell/cert-crypto.c
index 42f602e..ec14c04 100644
--- a/ell/cert-crypto.c
+++ b/ell/cert-crypto.c
@@ -175,7 +175,7 @@ static bool cert_pkcs5_pbkdf2(struct l_checksum *checksum, const uint8_t *salt,
 
 /* RFC8018 section 5.2 */
 LIB_EXPORT bool l_cert_pkcs5_pbkdf2(enum l_checksum_type type,
-					const char *password,
+					const char *password, size_t pass_len,
 					const uint8_t *salt, size_t salt_len,
 					unsigned int iter_count,
 					uint8_t *out_dk, size_t dk_len)
@@ -188,7 +188,7 @@ LIB_EXPORT bool l_cert_pkcs5_pbkdf2(enum l_checksum_type type,
 	if (!h_len)
 		return false;
 
-	checksum = l_checksum_new_hmac(type, password, strlen(password));
+	checksum = l_checksum_new_hmac(type, password, pass_len);
 	if (!checksum)
 		return false;
 
@@ -648,7 +648,8 @@ static struct l_cipher *cipher_from_pkcs5_pbes2_params(
 
 	/* RFC8018 section 6.2 */
 
-	if (!l_cert_pkcs5_pbkdf2(prf_alg, password, salt, salt_len, iter_count,
+	if (!l_cert_pkcs5_pbkdf2(prf_alg, password, strlen(password), salt,
+					salt_len, iter_count,
 					derived_key, key_len))
 		return NULL;
 
diff --git a/ell/cert.h b/ell/cert.h
index ce430fa..8ad57b6 100644
--- a/ell/cert.h
+++ b/ell/cert.h
@@ -73,6 +73,7 @@ bool l_cert_pkcs5_pbkdf1(enum l_checksum_type type, const char *password,
 				unsigned int iter_count,
 				uint8_t *out_dk, size_t dk_len);
 bool l_cert_pkcs5_pbkdf2(enum l_checksum_type type, const char *password,
+				size_t pass_len,
 				const uint8_t *salt, size_t salt_len,
 				unsigned int iter_count,
 				uint8_t *out_dk, size_t dk_len);
-- 
2.34.3