drivers: crypto: Add authenticated decryption framework

Add framework for autheticated decryption of data. Currently this
patch optionally imports mbedtls library as a backend if build option
"DECRYPTION_SUPPORT = aes_gcm" is set to perform authenticated decryption
using AES-GCM algorithm.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Change-Id: I2966f0e79033151012bf4ffc66f484cd949e7271

3 files changed, 45 insertions, 4 deletions

diff --git a/include/drivers/auth/crypto_mod.h b/include/drivers/auth/crypto_mod.h
index f211035d7..71cf67306 100644
--- a/include/drivers/auth/crypto_mod.h
+++ b/include/drivers/auth/crypto_mod.h
@@ -13,9 +13,18 @@ enum crypto_ret_value {
 	CRYPTO_ERR_INIT,
 	CRYPTO_ERR_HASH,
 	CRYPTO_ERR_SIGNATURE,
+	CRYPTO_ERR_DECRYPTION,
 	CRYPTO_ERR_UNKNOWN
 };
 
+#define CRYPTO_MAX_IV_SIZE		16U
+#define CRYPTO_MAX_TAG_SIZE		16U
+
+/* Decryption algorithm */
+enum crypto_dec_algo {
+	CRYPTO_GCM_DECRYPT = 0
+};
+
 /*
  * Cryptographic library descriptor
  */
@@ -44,6 +53,15 @@ typedef struct crypto_lib_desc_s {
 			 unsigned int data_len, unsigned char *output);
 #endif /* MEASURED_BOOT */
 
+	/*
+	 * Authenticated decryption. Return one of the
+	 * 'enum crypto_ret_value' options.
+	 */
+	int (*auth_decrypt)(enum crypto_dec_algo dec_algo, void *data_ptr,
+			    size_t len, const void *key, unsigned int key_len,
+			    unsigned int key_flags, const void *iv,
+			    unsigned int iv_len, const void *tag,
+			    unsigned int tag_len);
 } crypto_lib_desc_t;
 
 /* Public functions */
@@ -54,6 +72,11 @@ int crypto_mod_verify_signature(void *data_ptr, unsigned int data_len,
 				void *pk_ptr, unsigned int pk_len);
 int crypto_mod_verify_hash(void *data_ptr, unsigned int data_len,
 			   void *digest_info_ptr, unsigned int digest_info_len);
+int crypto_mod_auth_decrypt(enum crypto_dec_algo dec_algo, void *data_ptr,
+			    size_t len, const void *key, unsigned int key_len,
+			    unsigned int key_flags, const void *iv,
+			    unsigned int iv_len, const void *tag,
+			    unsigned int tag_len);
 
 #if MEASURED_BOOT
 int crypto_mod_calc_hash(unsigned int alg, void *data_ptr,
@@ -61,21 +84,24 @@ int crypto_mod_calc_hash(unsigned int alg, void *data_ptr,
 
 /* Macro to register a cryptographic library */
 #define REGISTER_CRYPTO_LIB(_name, _init, _verify_signature, _verify_hash, \
-							     _calc_hash) \
+			    _calc_hash, _auth_decrypt) \
 	const crypto_lib_desc_t crypto_lib_desc = { \
 		.name = _name, \
 		.init = _init, \
 		.verify_signature = _verify_signature, \
 		.verify_hash = _verify_hash, \
-		.calc_hash = _calc_hash \
+		.calc_hash = _calc_hash, \
+		.auth_decrypt = _auth_decrypt \
 	}
 #else
-#define REGISTER_CRYPTO_LIB(_name, _init, _verify_signature, _verify_hash) \
+#define REGISTER_CRYPTO_LIB(_name, _init, _verify_signature, _verify_hash, \
+			    _auth_decrypt) \
 	const crypto_lib_desc_t crypto_lib_desc = { \
 		.name = _name, \
 		.init = _init, \
 		.verify_signature = _verify_signature, \
-		.verify_hash = _verify_hash \
+		.verify_hash = _verify_hash, \
+		.auth_decrypt = _auth_decrypt \
 	}
 #endif	/* MEASURED_BOOT */
 
diff --git a/include/drivers/auth/mbedtls/mbedtls_config.h b/include/drivers/auth/mbedtls/mbedtls_config.h
index 6e179bbd1..dc00da7d6 100644
--- a/include/drivers/auth/mbedtls/mbedtls_config.h
+++ b/include/drivers/auth/mbedtls/mbedtls_config.h
@@ -79,6 +79,12 @@
 #define MBEDTLS_X509_USE_C
 #define MBEDTLS_X509_CRT_PARSE_C
 
+#if TF_MBEDTLS_USE_AES_GCM
+#define MBEDTLS_AES_C
+#define MBEDTLS_CIPHER_C
+#define MBEDTLS_GCM_C
+#endif
+
 /* MPI / BIGNUM options */
 #define MBEDTLS_MPI_WINDOW_SIZE			2
 
diff --git a/include/plat/common/platform.h b/include/plat/common/platform.h
index f5bd298c5..06b334d70 100644
--- a/include/plat/common/platform.h
+++ b/include/plat/common/platform.h
@@ -37,6 +37,15 @@ struct sp_res_desc;
 #define ROTPK_NOT_DEPLOYED		(1 << 1)
 
 /*******************************************************************************
+ * plat_get_enc_key_info() flags
+ ******************************************************************************/
+/*
+ * Flag used to notify caller that information provided in key buffer is an
+ * identifier rather than an actual key.
+ */
+#define ENC_KEY_IS_IDENTIFIER		(1 << 0)
+
+/*******************************************************************************
  * Function declarations
  ******************************************************************************/
 /*******************************************************************************