Commit 1d83177c authored by Dominik Ermel's avatar Dominik Ermel Committed by Dominik Ermel
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bootutil: Add support for HAMC-SHA512 with ECIES-X25519 



Add support for HKDF/HMAC based on SHA512 for ECIES-X25519 key
exchange.
The commit adds MCUBOOT_HMAC_SHA512 that enables new TLV
IMAGE_TLV_ENC_X25519_SHA512.
Encryption code has been altered to support the MCUBOOT_HMAC_SHA512.

Signed-off-by: default avatarDominik Ermel <dominik.ermel@nordicsemi.no>
parent e542295f

boot/bootutil/include/bootutil/enc_key_public.h

+15 −2
Original line number Diff line number Diff line
@@ -70,10 +70,19 @@ extern "C" { 
#   define BOOT_ENC_KEY_SIZE   16

#endif



#ifdef MCUBOOT_HMAC_SHA512

#   define BOOT_HMAC_SIZE      64

#else

#   define BOOT_HMAC_SIZE      32

#endif



#if defined(MCUBOOT_ENCRYPT_RSA)

#   define BOOT_ENC_TLV_SIZE   (256)

#   define BOOT_ENC_TLV        IMAGE_TLV_ENC_RSA2048

#elif defined(MCUBOOT_ENCRYPT_EC256)

#   if defined(MCUBOOT_HMAC_SHA512)

#       error "ECIES-P256 does not support HMAC-SHA512"

#   endif

#   define EC_PUBK_LEN         (65)

#   define EC_PRIVK_LEN        (32)

#   define EC_SHARED_LEN       (32)
@@ -82,7 +91,11 @@ extern "C" { 
#   define EC_PUBK_LEN         (32)

#   define EC_PRIVK_LEN        (32)

#   define EC_SHARED_LEN       (32)

#   if !defined(MCUBOOT_HMAC_SHA512)

#       define BOOT_ENC_TLV     IMAGE_TLV_ENC_X25519

#   else

#       define BOOT_ENC_TLV     IMAGE_TLV_ENC_X25519_SHA512

#   endif

#elif defined(MCUBOOT_ENCRYPT_KW)

#   define BOOT_ENC_TLV_SIZE   (BOOT_ENC_KEY_SIZE + 8)

#   define BOOT_ENC_TLV        IMAGE_TLV_ENC_KW
@@ -91,7 +104,7 @@ extern "C" { 
/* Common ECIES definitions */

#if defined(EC_PUBK_LEN)

#   define EC_PUBK_INDEX       (0)

#   define EC_TAG_LEN          (32)

#   define EC_TAG_LEN          (BOOT_HMAC_SIZE)

#   define EC_TAG_INDEX        (EC_PUBK_INDEX + EC_PUBK_LEN)

#   define EC_CIPHERKEY_INDEX  (EC_TAG_INDEX + EC_TAG_LEN)

#   define EC_CIPHERKEY_LEN    BOOT_ENC_KEY_SIZE

boot/bootutil/include/bootutil/image.h

+3 −0
Original line number Diff line number Diff line
@@ -113,6 +113,9 @@ extern "C" { 
#define IMAGE_TLV_ENC_KW            0x31    /* Key encrypted with AES-KW 128 or 256*/

#define IMAGE_TLV_ENC_EC256         0x32    /* Key encrypted with ECIES-EC256 */

#define IMAGE_TLV_ENC_X25519        0x33    /* Key encrypted with ECIES-X25519 */

#define IMAGE_TLV_ENC_X25519_SHA512 0x34    /* Key exchange using ECIES-X25519 and SHA512 for MAC

                                             * tag and HKDF in key derivation process

                                             */

#define IMAGE_TLV_DEPENDENCY        0x40    /* Image depends on other image */

#define IMAGE_TLV_SEC_CNT           0x50    /* security counter */

#define IMAGE_TLV_BOOT_RECORD       0x60    /* measured boot record */

boot/bootutil/src/encrypted_psa.c

+9 −3
Original line number Diff line number Diff line
@@ -27,6 +27,12 @@ 


BOOT_LOG_MODULE_DECLARE(mcuboot_psa_enc);



#if defined(MCUBOOT_HMAC_SHA512)

#define PSA_HMAC_HKDF_SHA PSA_ALG_SHA_512

#else

#define PSA_HMAC_HKDF_SHA PSA_ALG_SHA_256

#endif



#define X25519_OID "\x6e"

static const uint8_t ec_pubkey_oid[] = MBEDTLS_OID_ISO_IDENTIFIED_ORG \

                                       MBEDTLS_OID_ORG_GOV X25519_OID;
@@ -162,7 +168,7 @@ boot_decrypt_key(const uint8_t *buf, uint8_t *enckey) 
        return -1;

    }



    key_do_alg = PSA_ALG_KEY_AGREEMENT(PSA_ALG_ECDH, PSA_ALG_HKDF(PSA_ALG_SHA_256));

    key_do_alg = PSA_ALG_KEY_AGREEMENT(PSA_ALG_ECDH, PSA_ALG_HKDF(PSA_HMAC_HKDF_SHA));



    psa_ret = psa_key_derivation_setup(&key_do, key_do_alg);

    if (psa_ret != PSA_SUCCESS) {
@@ -225,7 +231,7 @@ boot_decrypt_key(const uint8_t *buf, uint8_t *enckey) 
     */

    psa_set_key_type(&kattr, PSA_KEY_TYPE_HMAC);

    psa_set_key_usage_flags(&kattr, PSA_KEY_USAGE_VERIFY_MESSAGE);

    psa_set_key_algorithm(&kattr, PSA_ALG_HMAC(PSA_ALG_SHA_256));

    psa_set_key_algorithm(&kattr, PSA_ALG_HMAC(PSA_HMAC_HKDF_SHA));



    /* Import the MAC tag key part of derived key */

    psa_ret = psa_import_key(&kattr,
@@ -239,7 +245,7 @@ boot_decrypt_key(const uint8_t *buf, uint8_t *enckey) 
    }



    /* Verify the MAC tag of the random encryption key */

    psa_ret = psa_mac_verify(kid, PSA_ALG_HMAC(PSA_ALG_SHA_256),

    psa_ret = psa_mac_verify(kid, PSA_ALG_HMAC(PSA_HMAC_HKDF_SHA),

                             &buf[EC_CIPHERKEY_INDEX], EC_CIPHERKEY_LEN,

                             &buf[EC_TAG_INDEX],

                             EC_TAG_LEN);

boot/bootutil/src/image_validate.c

+4 −0
Original line number Diff line number Diff line
@@ -474,7 +474,11 @@ static const uint16_t allowed_unprot_tlvs[] = { 
     IMAGE_TLV_ENC_RSA2048,

     IMAGE_TLV_ENC_KW,

     IMAGE_TLV_ENC_EC256,

#if !defined(MCUBOOT_HMAC_SHA512)

     IMAGE_TLV_ENC_X25519,

#else

     IMAGE_TLV_ENC_X25519_SHA512,

#endif

     /* Mark end with ANY. */

     IMAGE_TLV_ANY,

};

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