diff --git a/docs/user-guide.rst b/docs/user-guide.rst
index 043af63ed10dd00d557df20024330f68ba2a2267..1181495cfc77a12efdb39c95efcd985dcddbcebf 100644
--- a/docs/user-guide.rst
+++ b/docs/user-guide.rst
@@ -405,6 +405,13 @@ Common build options
AArch64 and facilitates the loading of ``SP_MIN`` and BL33 as AArch32 executable
images.
+- ``KEY_ALG``: This build flag enables the user to select the algorithm to be
+ used for generating the PKCS keys and subsequent signing of the certificate.
+ It accepts 3 values viz ``rsa``, ``rsa_1_5``, ``ecdsa``. The ``rsa_1_5`` is
+ the legacy PKCS#1 RSA 1.5 algorithm which is not TBBR compliant and is
+ retained only for compatibility. The default value of this flag is ``rsa``
+ which is the TBBR compliant PKCS#1 RSA 2.1 scheme.
+
- ``LDFLAGS``: Extra user options appended to the linkers' command line in
addition to the one set by the build system.
diff --git a/drivers/auth/mbedtls/mbedtls_crypto.mk b/drivers/auth/mbedtls/mbedtls_crypto.mk
index cb81d4d6741cf1be452b303ae30fdb4a6fbf7afe..21b857bffe4a3465daaee700776674cdbce20165 100644
--- a/drivers/auth/mbedtls/mbedtls_crypto.mk
+++ b/drivers/auth/mbedtls/mbedtls_crypto.mk
@@ -7,9 +7,15 @@
include drivers/auth/mbedtls/mbedtls_common.mk
# The platform may define the variable 'TF_MBEDTLS_KEY_ALG' to select the key
-# algorithm to use. Default algorithm is RSA.
+# algorithm to use. If the variable is not defined, select it based on algorithm
+# used for key generation `KEY_ALG`. If `KEY_ALG` is not defined or is
+# defined to `rsa`/`rsa_1_5`, then set the variable to `rsa`.
ifeq (${TF_MBEDTLS_KEY_ALG},)
- TF_MBEDTLS_KEY_ALG := rsa
+ ifeq (${KEY_ALG}, ecdsa)
+ TF_MBEDTLS_KEY_ALG := ecdsa
+ else
+ TF_MBEDTLS_KEY_ALG := rsa
+ endif
endif
# If MBEDTLS_KEY_ALG build flag is defined use it to set TF_MBEDTLS_KEY_ALG for
diff --git a/make_helpers/defaults.mk b/make_helpers/defaults.mk
index 302d937f30fade7ab086c08ef659aab86adaeaf9..860104605ccef1e4b96bbe901309518be6838081 100644
--- a/make_helpers/defaults.mk
+++ b/make_helpers/defaults.mk
@@ -81,6 +81,9 @@ GENERATE_COT := 0
# operations.
HW_ASSISTED_COHERENCY := 0
+# Set the default algorithm for the generation of Trusted Board Boot keys
+KEY_ALG := rsa
+
# Flag to enable new version of image loading
LOAD_IMAGE_V2 := 0
diff --git a/plat/arm/common/arm_common.mk b/plat/arm/common/arm_common.mk
index 20372c2036304fbeea89f4cabfeb586d8b4578e7..af94ac2acd5b37fe714aec5a879f5dd9385f61d4 100644
--- a/plat/arm/common/arm_common.mk
+++ b/plat/arm/common/arm_common.mk
@@ -174,9 +174,6 @@ endif
ifneq (${TRUSTED_BOARD_BOOT},0)
- # By default, ARM platforms use RSA keys
- KEY_ALG := rsa
-
# Include common TBB sources
AUTH_SOURCES := drivers/auth/auth_mod.c \
drivers/auth/crypto_mod.c \
@@ -195,8 +192,6 @@ ifneq (${TRUSTED_BOARD_BOOT},0)
$(eval $(call FWU_FIP_ADD_IMG,NS_BL2U,--fwu))
- TF_MBEDTLS_KEY_ALG := ${KEY_ALG}
-
# We expect to locate the *.mk files under the directories specified below
ifeq (${ARM_CRYPTOCELL_INTEG},0)
CRYPTO_LIB_MK := drivers/auth/mbedtls/mbedtls_crypto.mk
diff --git a/tools/cert_create/include/cert.h b/tools/cert_create/include/cert.h
index 543f12233aa4fcd4c9dac74a77288c86972e67d9..256e7afd25b0cd6f5b23d1484a46995cac97c804 100644
--- a/tools/cert_create/include/cert.h
+++ b/tools/cert_create/include/cert.h
@@ -48,7 +48,7 @@ struct cert_s {
int cert_init(void);
cert_t *cert_get_by_opt(const char *opt);
int cert_add_ext(X509 *issuer, X509 *subject, int nid, char *value);
-int cert_new(cert_t *cert, int days, int ca, STACK_OF(X509_EXTENSION) * sk);
+int cert_new(int key_alg, cert_t *cert, int days, int ca, STACK_OF(X509_EXTENSION) * sk);
/* Macro to register the certificates used in the CoT */
#define REGISTER_COT(_certs) \
diff --git a/tools/cert_create/include/key.h b/tools/cert_create/include/key.h
index 4b9e88258c3ef9468c6114cda95f103f99124ff1..304fa6154f80fa8ca92342c3f44d12ffddce1ea2 100644
--- a/tools/cert_create/include/key.h
+++ b/tools/cert_create/include/key.h
@@ -22,7 +22,8 @@ enum {
/* Supported key algorithms */
enum {
- KEY_ALG_RSA,
+ KEY_ALG_RSA, /* RSA PSS as defined by PKCS#1 v2.1 (default) */
+ KEY_ALG_RSA_1_5, /* RSA as defined by PKCS#1 v1.5 */
#ifndef OPENSSL_NO_EC
KEY_ALG_ECDSA,
#endif /* OPENSSL_NO_EC */
diff --git a/tools/cert_create/src/cert.c b/tools/cert_create/src/cert.c
index 9775664a38d3d2b9cb9805a804b99ca24b7de80c..1b84e36d35ac020e86d3e58f24a67fca443f7c59 100644
--- a/tools/cert_create/src/cert.c
+++ b/tools/cert_create/src/cert.c
@@ -79,7 +79,7 @@ int cert_add_ext(X509 *issuer, X509 *subject, int nid, char *value)
return 1;
}
-int cert_new(cert_t *cert, int days, int ca, STACK_OF(X509_EXTENSION) * sk)
+int cert_new(int key_alg, cert_t *cert, int days, int ca, STACK_OF(X509_EXTENSION) * sk)
{
EVP_PKEY *pkey = keys[cert->key].key;
cert_t *issuer_cert = &certs[cert->issuer];
@@ -90,7 +90,7 @@ int cert_new(cert_t *cert, int days, int ca, STACK_OF(X509_EXTENSION) * sk)
X509_NAME *name;
ASN1_INTEGER *sno;
int i, num, rc = 0;
- EVP_MD_CTX mdCtx;
+ EVP_MD_CTX mdCtx;
EVP_PKEY_CTX *pKeyCtx = NULL;
/* Create the certificate structure */
@@ -112,24 +112,32 @@ int cert_new(cert_t *cert, int days, int ca, STACK_OF(X509_EXTENSION) * sk)
}
EVP_MD_CTX_init(&mdCtx);
+
+ /* Sign the certificate with the issuer key */
if (!EVP_DigestSignInit(&mdCtx, &pKeyCtx, EVP_sha256(), NULL, ikey)) {
ERR_print_errors_fp(stdout);
goto END;
}
- if (!EVP_PKEY_CTX_set_rsa_padding(pKeyCtx, RSA_PKCS1_PSS_PADDING)) {
- ERR_print_errors_fp(stdout);
- goto END;
- }
+ /*
+ * Set additional parameters if algorithm is RSA PSS. This is not
+ * required for RSA 1.5 or ECDSA.
+ */
+ if (key_alg == KEY_ALG_RSA) {
+ if (!EVP_PKEY_CTX_set_rsa_padding(pKeyCtx, RSA_PKCS1_PSS_PADDING)) {
+ ERR_print_errors_fp(stdout);
+ goto END;
+ }
- if (!EVP_PKEY_CTX_set_rsa_pss_saltlen(pKeyCtx, RSA_SALT_LEN)) {
- ERR_print_errors_fp(stdout);
- goto END;
- }
+ if (!EVP_PKEY_CTX_set_rsa_pss_saltlen(pKeyCtx, RSA_SALT_LEN)) {
+ ERR_print_errors_fp(stdout);
+ goto END;
+ }
- if (!EVP_PKEY_CTX_set_rsa_mgf1_md(pKeyCtx, EVP_sha256())) {
- ERR_print_errors_fp(stdout);
- goto END;
+ if (!EVP_PKEY_CTX_set_rsa_mgf1_md(pKeyCtx, EVP_sha256())) {
+ ERR_print_errors_fp(stdout);
+ goto END;
+ }
}
/* x509.v3 */
diff --git a/tools/cert_create/src/main.c b/tools/cert_create/src/main.c
index f14601c8bc52e12360806d27d551b51891967173..df59961b0ac18b07c386355e853f031199fd3a56 100644
--- a/tools/cert_create/src/main.c
+++ b/tools/cert_create/src/main.c
@@ -89,6 +89,7 @@ static char *strdup(const char *str)
static const char *key_algs_str[] = {
[KEY_ALG_RSA] = "rsa",
+ [KEY_ALG_RSA_1_5] = "rsa_1_5",
#ifndef OPENSSL_NO_EC
[KEY_ALG_ECDSA] = "ecdsa"
#endif /* OPENSSL_NO_EC */
@@ -223,7 +224,8 @@ static const cmd_opt_t common_cmd_opt[] = {
},
{
{ "key-alg", required_argument, NULL, 'a' },
- "Key algorithm: 'rsa' (default), 'ecdsa'"
+ "Key algorithm: 'rsa' (default) - RSAPSS scheme as per \
+PKCS#1 v2.1, 'rsa_1_5' - RSA PKCS#1 v1.5, 'ecdsa'"
},
{
{ "save-keys", no_argument, NULL, 'k' },
@@ -450,8 +452,8 @@ int main(int argc, char *argv[])
sk_X509_EXTENSION_push(sk, cert_ext);
}
- /* Create certificate. Signed with ROT key */
- if (cert->fn && !cert_new(cert, VAL_DAYS, 0, sk)) {
+ /* Create certificate. Signed with corresponding key */
+ if (cert->fn && !cert_new(key_alg, cert, VAL_DAYS, 0, sk)) {
ERROR("Cannot create %s\n", cert->cn);
exit(1);
}