Digital Signature HW: adding S2 support

components/esp32s2/CMakeLists.txt

@@ -25,7 +25,8 @@ else()
              "spiram_psram.c"
              "system_api_esp32s2.c"
              "esp_crypto_lock.c"
-             "esp_hmac.c")
+             "esp_hmac.c"
+             "esp_ds.c")
 
     set(include_dirs "include")
 

components/esp32s2/esp_ds.c

@@ -0,0 +1,196 @@
+// Copyright 2020 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#include "esp32s2/rom/aes.h"
+#include "esp32s2/rom/sha.h"
+#include "esp32s2/rom/hmac.h"
+#include "esp32s2/rom/digital_signature.h"
+
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "soc/soc_memory_layout.h"
+#include "esp_crypto_lock.h"
+#include "esp_hmac.h"
+
+#include "esp_ds.h"
+
+struct esp_ds_context {
+    const ets_ds_data_t *data;
+};
+
+/**
+ * The vtask delay \c esp_ds_sign() is using while waiting for completion of the signing operation.
+ */
+#define ESP_DS_SIGN_TASK_DELAY_MS 10
+
+#define RSA_LEN_MAX 127
+
+/*
+ * Check that the size of esp_ds_data_t and ets_ds_data_t is the same because both structs are converted using
+ * raw casts.
+ */
+_Static_assert(sizeof(esp_ds_data_t) == sizeof(ets_ds_data_t),
+        "The size and structure of esp_ds_data_t and ets_ds_data_t must match exactly, they're used in raw casts");
+
+/*
+ * esp_digital_signature_length_t is used in esp_ds_data_t in contrast to ets_ds_data_t, where unsigned is used.
+ * Check esp_digital_signature_length_t's width here because it's converted to unsigned using raw casts.
+ */
+_Static_assert(sizeof(esp_digital_signature_length_t) == sizeof(unsigned),
+        "The size of esp_digital_signature_length_t and unsigned has to be the same");
+
+static void ds_acquire_enable(void) {
+    esp_crypto_lock_acquire();
+    ets_hmac_enable();
+    ets_ds_enable();
+}
+
+static void ds_disable_release(void) {
+    ets_ds_disable();
+    ets_hmac_disable();
+    esp_crypto_lock_release();
+}
+
+esp_err_t esp_ds_sign(const void *message,
+        const esp_ds_data_t *data,
+        hmac_key_id_t key_id,
+        void *signature)
+{
+    // Need to check signature here, otherwise the signature is only checked when the signing has finished and fails
+    // but the signing isn't uninitialized and the mutex is still locked.
+    if (!signature) return ESP_ERR_INVALID_ARG;
+
+    esp_ds_context_t *context;
+    esp_err_t result = esp_ds_start_sign(message, data, key_id, &context);
+    if (result != ESP_OK) return result;
+
+    while (esp_ds_is_busy())
+        vTaskDelay(ESP_DS_SIGN_TASK_DELAY_MS / portTICK_PERIOD_MS);
+
+    return esp_ds_finish_sign(signature, context);
+}
+
+esp_err_t esp_ds_start_sign(const void *message,
+        const esp_ds_data_t *data,
+        hmac_key_id_t key_id,
+        esp_ds_context_t **esp_ds_ctx)
+{
+    if (!message || !data || !esp_ds_ctx) return ESP_ERR_INVALID_ARG;
+    if (key_id >= HMAC_KEY_MAX) return ESP_ERR_INVALID_ARG;
+    if (!(data->rsa_length == ESP_DS_RSA_1024
+            || data->rsa_length == ESP_DS_RSA_2048
+            || data->rsa_length == ESP_DS_RSA_3072
+            || data->rsa_length == ESP_DS_RSA_4096)) {
+        return ESP_ERR_INVALID_ARG;
+    }
+
+    ds_acquire_enable();
+
+    // initiate hmac
+    int r = ets_hmac_calculate_downstream(ETS_EFUSE_BLOCK_KEY0 + (ets_efuse_block_t) key_id,
+                                          ETS_EFUSE_KEY_PURPOSE_HMAC_DOWN_DIGITAL_SIGNATURE);
+    if (r != ETS_OK) {
+        ds_disable_release();
+        return ESP_ERR_HW_CRYPTO_DS_HMAC_FAIL;
+    }
+
+    esp_ds_context_t *context = malloc(sizeof(esp_ds_context_t));
+    if (!context) {
+        ds_disable_release();
+        return ESP_ERR_NO_MEM;
+    }
+
+    ets_ds_data_t *ds_data = (ets_ds_data_t*) data;
+
+    // initiate signing
+    ets_ds_result_t result = ets_ds_start_sign(message, ds_data);
+
+    // ETS_DS_INVALID_PARAM only happens if a parameter is NULL or data->rsa_length is wrong
+    // We checked all of that already
+    assert(result != ETS_DS_INVALID_PARAM);
+
+    if (result == ETS_DS_INVALID_KEY) {
+        ds_disable_release();
+        return ESP_ERR_HW_CRYPTO_DS_INVALID_KEY;
+    }
+
+    context->data = ds_data;
+    *esp_ds_ctx = context;
+
+    return ESP_OK;
+}
+
+bool esp_ds_is_busy(void)
+{
+    return ets_ds_is_busy();
+}
+
+esp_err_t esp_ds_finish_sign(void *signature, esp_ds_context_t *esp_ds_ctx)
+{
+    if (!signature || !esp_ds_ctx) return ESP_ERR_INVALID_ARG;
+
+    const ets_ds_data_t *ds_data = esp_ds_ctx->data;
+
+    ets_ds_result_t result = ets_ds_finish_sign(signature, ds_data);
+
+    esp_err_t return_value = ESP_OK;
+
+    // we checked all the parameters
+    assert(result != ETS_DS_INVALID_PARAM);
+
+    if (result == ETS_DS_INVALID_DIGEST) return_value = ESP_ERR_HW_CRYPTO_DS_INVALID_DIGEST;
+    if (result == ETS_DS_INVALID_PADDING) return_value = ESP_ERR_HW_CRYPTO_DS_INVALID_PADDING;
+
+    free(esp_ds_ctx);
+
+    // should not fail if called with correct purpose
+    assert(ets_hmac_invalidate_downstream(ETS_EFUSE_KEY_PURPOSE_HMAC_DOWN_DIGITAL_SIGNATURE) == ETS_OK);
+
+    ds_disable_release();
+
+    return return_value;
+}
+
+esp_err_t esp_ds_encrypt_params(esp_ds_data_t *data,
+        const void *iv,
+        const esp_ds_p_data_t *p_data,
+        const void *key)
+{
+    // p_data has to be valid, in internal memory and word aligned
+    if (!p_data) return ESP_ERR_INVALID_ARG;
+    assert(esp_ptr_internal(p_data) && esp_ptr_word_aligned(p_data));
+
+    esp_err_t result = ESP_OK;
+
+    esp_crypto_lock_acquire();
+    ets_aes_enable();
+    ets_sha_enable();
+
+    ets_ds_data_t *ds_data = (ets_ds_data_t*) data;
+    const ets_ds_p_data_t *ds_plain_data = (const ets_ds_p_data_t*) p_data;
+
+    ets_ds_result_t ets_result = ets_ds_encrypt_params(ds_data, iv, ds_plain_data, key, ETS_DS_KEY_HMAC);
+
+    if (ets_result == ETS_DS_INVALID_PARAM) result = ESP_ERR_INVALID_ARG;
+
+    ets_sha_disable();
+    ets_aes_disable();
+    esp_crypto_lock_release();
+
+    return result;
+}

components/esp32s2/include/esp_ds.h

@@ -0,0 +1,196 @@
+// Copyright 2020 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include "esp_hmac.h"
+#include "esp_err.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define ESP_ERR_HW_CRYPTO_DS_BASE 0xc000 /*!< Starting number of HW cryptography module error codes */
+#define ESP_ERR_HW_CRYPTO_DS_HMAC_FAIL           ESP_ERR_HW_CRYPTO_DS_BASE + 0x1 /*!< HMAC peripheral problem */
+#define ESP_ERR_HW_CRYPTO_DS_INVALID_KEY         ESP_ERR_HW_CRYPTO_DS_BASE + 0x2 /*!< given HMAC key isn't correct,
+                                                                                   HMAC peripheral problem */
+#define ESP_ERR_HW_CRYPTO_DS_INVALID_DIGEST      ESP_ERR_HW_CRYPTO_DS_BASE + 0x4 /*!< message digest check failed,
+                                                                                   result is invalid */
+#define ESP_ERR_HW_CRYPTO_DS_INVALID_PADDING     ESP_ERR_HW_CRYPTO_DS_BASE + 0x5 /*!< padding check failed, but result
+                                                                                   is produced anyway and can be read*/
+
+#define ESP_DS_IV_LEN 16
+
+/* Length of parameter 'C' stored in flash */
+#define ESP_DS_C_LEN (12672 / 8)
+
+typedef struct esp_ds_context esp_ds_context_t;
+
+typedef enum {
+    ESP_DS_RSA_1024 = (1024 / 32) - 1,
+    ESP_DS_RSA_2048 = (2048 / 32) - 1,
+    ESP_DS_RSA_3072 = (3072 / 32) - 1,
+    ESP_DS_RSA_4096 = (4096 / 32) - 1
+} esp_digital_signature_length_t;
+
+/**
+ * Encrypted private key data. Recommended to store in flash in this format.
+ *
+ * @note This struct has to match to one from the ROM code! This documentation is mostly taken from there.
+ */
+typedef struct esp_digital_signature_data {
+    /* RSA LENGTH register parameters
+     * (number of words in RSA key & operands, minus one).
+     *
+     * Max value 127 (for RSA 4096).
+     *
+     * This value must match the length field encrypted and stored in 'c',
+     * or invalid results will be returned. (The DS peripheral will
+     * always use the value in 'c', not this value, so an attacker can't
+     * alter the DS peripheral results this way, it will just truncate or
+     * extend the message and the resulting signature in software.)
+     *
+     * @note In IDF, the enum type length is the same as of type unsigned, so they can be used interchangably.
+     *       See the ROM code for the original declaration of struct \c ets_ds_data_t.
+     */
+    esp_digital_signature_length_t rsa_length;
+
+    /* IV value used to encrypt 'c' */
+    uint8_t iv[ESP_DS_IV_LEN];
+
+    /* Encrypted Digital Signature parameters. Result of AES-CBC encryption
+       of plaintext values. Includes an encrypted message digest.
+    */
+    uint8_t c[ESP_DS_C_LEN];
+} esp_ds_data_t;
+
+/* Plaintext parameters used by Digital Signature.
+ *
+ * Not used for signing with DS peripheral, but can be encrypted
+ * in-device by calling esp_ds_encrypt_params()
+ *
+ * @note This documentation is mostly taken from the ROM code.
+ */
+typedef struct {
+    uint32_t Y[4096/32];
+    uint32_t M[4096/32];
+    uint32_t Rb[4096/32];
+    uint32_t M_prime;
+    esp_digital_signature_length_t length;
+} esp_ds_p_data_t;
+
+/**
+ * Sign the message.
+ *
+ * This function is a wrapper around \c esp_ds_finish_sign() and \c esp_ds_start_sign(), so do not use them
+ * in parallel.
+ * It blocks until the signing is finished and then returns the signature.
+ *
+ * @note This function locks the HMAC, SHA and AES components during its entire execution time.
+ *
+ * @param message the message to be signed; its length is determined by data->rsa_length
+ * @param data the encrypted signing key data (AES encrypted RSA key + IV)
+ * @param key_id the HMAC key ID determining the HMAC key of the HMAC which will be used to decrypt the
+ *        signing key data
+ * @param signature the destination of the signature, should be (data->rsa_length + 1)*4 bytes long
+ *
+ * @return
+ *      - ESP_OK if successful, the signature was written to the parameter \c signature.
+ *      - ESP_ERR_INVALID_ARG if one of the parameters is NULL or data->rsa_length is too long or 0
+ *      - ESP_ERR_HW_CRYPTO_DS_HMAC_FAIL if there was an HMAC failure during retrieval of the decryption key
+ *      - ESP_ERR_NO_MEM if there hasn't been enough memory to allocate the context object
+ *      - ESP_ERR_HW_CRYPTO_DS_INVALID_KEY if there's a problem with passing the HMAC key to the DS component
+ *      - ESP_ERR_HW_CRYPTO_DS_INVALID_DIGEST if the message digest didn't match; the signature is invalid.
+ *      - ESP_ERR_HW_CRYPTO_DS_INVALID_PADDING if the message padding is incorrect, the signature can be read though
+ *        since the message digest matches.
+ */
+esp_err_t esp_ds_sign(const void *message,
+        const esp_ds_data_t *data,
+        hmac_key_id_t key_id,
+        void *signature);
+
+/**
+ * Start the signing process.
+ *
+ * This function yields a context object which needs to be passed to \c esp_ds_finish_sign() to finish the signing
+ * process.
+ *
+ * @note This function locks the HMAC, SHA and AES components, so the user has to ensure to call
+ *       \c esp_ds_finish_sign() in a timely manner.
+ *
+ * @param message the message to be signed; its length is determined by data->rsa_length
+ * @param data the encrypted signing key data (AES encrypted RSA key + IV)
+ * @param key_id the HMAC key ID determining the HMAC key of the HMAC which will be used to decrypt the
+ *        signing key data
+ * @param esp_ds_ctx the context object which is needed for finishing the signing process later
+ *
+ * @return
+ *      - ESP_OK if successful, the ds operation was started now and has to be finished with \c esp_ds_finish_sign()
+ *      - ESP_ERR_INVALID_ARG if one of the parameters is NULL or data->rsa_length is too long or 0
+ *      - ESP_ERR_HW_CRYPTO_DS_HMAC_FAIL if there was an HMAC failure during retrieval of the decryption key
+ *      - ESP_ERR_NO_MEM if there hasn't been enough memory to allocate the context object
+ *      - ESP_ERR_HW_CRYPTO_DS_INVALID_KEY if there's a problem with passing the HMAC key to the DS component
+ */
+esp_err_t esp_ds_start_sign(const void *message,
+        const esp_ds_data_t *data,
+        hmac_key_id_t key_id,
+        esp_ds_context_t **esp_ds_ctx);
+
+/**
+ * Return true if the DS peripheral is busy, otherwise false.
+ *
+ * @note Only valid if \c esp_ds_start_sign() was called before.
+ */
+bool esp_ds_is_busy(void);
+
+/**
+ * Finish the signing process.
+ *
+ * @param signature the destination of the signature, should be (data->rsa_length + 1)*4 bytes long
+ * @param esp_ds_ctx the context object retreived by \c esp_ds_start_sign()
+ *
+ * @return
+ *      - ESP_OK if successful, the ds operation has been finished and the result is written to signature.
+ *      - ESP_ERR_INVALID_ARG if one of the parameters is NULL
+ *      - ESP_ERR_HW_CRYPTO_DS_INVALID_DIGEST if the message digest didn't match; the signature is invalid.
+ *      - ESP_ERR_HW_CRYPTO_DS_INVALID_PADDING if the message padding is incorrect, the signature can be read though
+ *        since the message digest matches.
+ */
+esp_err_t esp_ds_finish_sign(void *signature, esp_ds_context_t *esp_ds_ctx);
+
+/**
+ * Encrypt the private key parameters.
+ *
+ * @param data Output buffer to store encrypted data, suitable for later use generating signatures.
+ *        The allocated memory must be in internal memory and word aligned since it's filled by DMA. Both is asserted
+ *        at run time.
+ * @param iv Pointer to 16 byte IV buffer, will be copied into 'data'. Should be randomly generated bytes each time.
+ * @param p_data Pointer to input plaintext key data. The expectation is this data will be deleted after this process
+ *        is done and 'data' is stored.
+ * @param key Pointer to 32 bytes of key data. Type determined by key_type parameter. The expectation is the
+ *        corresponding HMAC key will be stored to efuse and then permanently erased.
+ *
+ * @return
+ *      - ESP_OK if successful, the ds operation has been finished and the result is written to signature.
+ *      - ESP_ERR_INVALID_ARG if one of the parameters is NULL or p_data->rsa_length is too long
+ */
+esp_err_t esp_ds_encrypt_params(esp_ds_data_t *data,
+        const void *iv,
+        const esp_ds_p_data_t *p_data,
+        const void *key);
+
+#ifdef __cplusplus
+}
+#endif
+

components/esp32s2/test/gen_digital_signature_tests.py

@@ -0,0 +1,150 @@
+#!/usr/bin/env python3
+
+import hashlib
+import hmac
+import struct
+import os
+import random
+from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
+
+from cryptography.hazmat.primitives.asymmetric import rsa
+from cryptography.hazmat.backends import default_backend
+from cryptography.utils import int_to_bytes
+
+
+def number_as_bignum_words(number):
+    """
+    Given a number, format result as a C array of words
+    (little-endian, same as ESP32 RSA peripheral or mbedTLS)
+    """
+    result = []
+    while number != 0:
+        result.append("0x%08x" % (number & 0xFFFFFFFF))
+        number >>= 32
+    return "{ " + ", ".join(result) + " }"
+
+
+def number_as_bytes(number, pad_bits=None):
+    """
+    Given a number, format as a little endian array of bytes
+    """
+    result = int_to_bytes(number)[::-1]
+    while pad_bits is not None and len(result) < (pad_bits // 8):
+        result += b'\x00'
+    return result
+
+
+def bytes_as_char_array(b):
+    """
+    Given a sequence of bytes, format as a char array
+    """
+    return "{ " + ", ".join("0x%02x" % x for x in b) + " }"
+
+
+NUM_HMAC_KEYS = 3
+NUM_MESSAGES = 10
+NUM_CASES = 6
+
+
+hmac_keys = [os.urandom(32) for x in range(NUM_HMAC_KEYS)]
+
+messages = [random.randrange(0, 1 << 4096) for x in range(NUM_MESSAGES)]
+
+with open("digital_signature_test_cases.h", "w") as f:
+    f.write("/* File generated by gen_digital_signature_tests.py */\n\n")
+
+    # Write out HMAC keys
+    f.write("#define NUM_HMAC_KEYS %d\n\n" % NUM_HMAC_KEYS)
+    f.write("static const uint8_t test_hmac_keys[NUM_HMAC_KEYS][32] = {\n")
+    for h in hmac_keys:
+        f.write("     %s,\n" % bytes_as_char_array(h))
+    f.write("};\n\n")
+
+    # Write out messages
+    f.write("#define NUM_MESSAGES %d\n\n" % NUM_MESSAGES)
+    f.write("static const uint32_t test_messages[NUM_MESSAGES][4096/32] = {\n")
+    for m in messages:
+        f.write("        // Message %d\n" % messages.index(m))
+        f.write("        %s,\n" % number_as_bignum_words(m))
+    f.write("    };\n")
+    f.write("\n\n\n")
+
+    f.write("#define NUM_CASES %d\n\n" % NUM_CASES)
+    f.write("static const encrypt_testcase_t test_cases[NUM_CASES] = {\n")
+
+    for case in range(NUM_CASES):
+        f.write("    { /* Case %d */\n" % case)
+
+        iv = os.urandom(16)
+        f.write("        .iv = %s,\n" % (bytes_as_char_array(iv)))
+
+        hmac_key_idx = random.randrange(0, NUM_HMAC_KEYS)
+        aes_key = hmac.HMAC(hmac_keys[hmac_key_idx], b"\xFF" * 32, hashlib.sha256).digest()
+
+        sizes = [4096, 3072, 2048, 1024, 512]
+        key_size = sizes[case % len(sizes)]
+
+        private_key = rsa.generate_private_key(
+            public_exponent=65537,
+            key_size=key_size,
+            backend=default_backend())
+
+        priv_numbers = private_key.private_numbers()
+        pub_numbers = private_key.public_key().public_numbers()
+        Y = priv_numbers.d
+        M = pub_numbers.n
+
+        rr = 1 << (key_size * 2)
+        rinv = rr % pub_numbers.n
+        mprime = - rsa._modinv(M, 1 << 32)
+        mprime &= 0xFFFFFFFF
+        length = key_size // 32 - 1
+
+        f.write("        .p_data = {\n")
+        f.write("            .Y = %s,\n" % number_as_bignum_words(Y))
+        f.write("            .M = %s,\n" % number_as_bignum_words(M))
+        f.write("            .Rb = %s,\n" % number_as_bignum_words(rinv))
+        f.write("            .M_prime = 0x%08x,\n" % mprime)
+        f.write("            .length = %d, // %d bit\n" % (length, key_size))
+        f.write("        },\n")
+
+        # calculate MD from preceding values and IV
+
+        # Y4096 || M4096 || Rb4096 || M_prime32 || LENGTH32 || IV128
+        md_in = number_as_bytes(Y, 4096) + \
+            number_as_bytes(M, 4096) + \
+            number_as_bytes(rinv, 4096) + \
+            struct.pack("<II", mprime, length) + \
+            iv
+        assert len(md_in) == 12480 / 8
+        md = hashlib.sha256(md_in).digest()
+
+        # generate expected C value from P bitstring
+        #
+        # Y4096 || M4096 || Rb4096 || M_prime32 || LENGTH32 || MD256 || 0x08*8
+        p = number_as_bytes(Y, 4096) + \
+            number_as_bytes(M, 4096) + \
+            number_as_bytes(rinv, 4096) + \
+            md + \
+            struct.pack("<II", mprime, length) + \
+            b'\x08' * 8
+
+        assert len(p) == 12672 / 8
+
+        cipher = Cipher(algorithms.AES(aes_key), modes.CBC(iv), backend=default_backend())
+        encryptor = cipher.encryptor()
+        c = encryptor.update(p) + encryptor.finalize()
+
+        f.write("        .expected_c = %s,\n" % bytes_as_char_array(c))
+        f.write("        .hmac_key_idx = %d,\n" % (hmac_key_idx))
+
+        f.write("        // results of message array encrypted with these keys\n")
+        f.write("        .expected_results = {\n")
+        mask = (1 << key_size) - 1  # truncate messages if needed
+        for m in messages:
+            f.write("        // Message %d\n" % messages.index(m))
+            f.write("      %s," % (number_as_bignum_words(pow(m & mask, Y, M))))
+        f.write("     },\n")
+        f.write("     },\n")
+
+    f.write("};\n")

components/esp32s2/test/test_ds.c

@@ -0,0 +1,383 @@
+// Copyright 2020 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "unity.h"
+#include "esp32s2/rom/efuse.h"
+#include "esp32s2/rom/digital_signature.h"
+#include "esp32s2/rom/aes.h"
+#include "esp32s2/rom/sha.h"
+#include <string.h>
+
+#include "esp_ds.h"
+
+#if CONFIG_IDF_TARGET_ESP32S2
+
+#define NUM_RESULTS 10
+
+typedef struct {
+    uint8_t iv[ETS_DS_IV_LEN];
+    ets_ds_p_data_t p_data;
+    uint8_t expected_c[ETS_DS_C_LEN];
+    uint8_t hmac_key_idx;
+    uint32_t expected_results[NUM_RESULTS][4096/32];
+} encrypt_testcase_t;
+
+// Generated header (gen_digital_signature_tests.py) defines
+// NUM_HMAC_KEYS, test_hmac_keys, NUM_MESSAGES, NUM_CASES, test_messages[], test_cases[]
+// Some adaptations were made: removed the 512 bit case and changed RSA lengths to the enums from esp_ds.h
+#include "digital_signature_test_cases.h"
+
+_Static_assert(NUM_RESULTS == NUM_MESSAGES, "expected_results size should be the same as NUM_MESSAGES in generated header");
+
+TEST_CASE("Digital Signature Parameter Encryption data NULL", "[hw_crypto]")
+{
+    const char iv [32];
+    esp_ds_p_data_t p_data;
+    const char key [32];
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_encrypt_params(NULL, iv, &p_data, key));
+}
+
+TEST_CASE("Digital Signature Parameter Encryption iv NULL", "[hw_crypto]")
+{
+    esp_ds_data_t data;
+    esp_ds_p_data_t p_data;
+    const char key [32];
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_encrypt_params(&data, NULL, &p_data, key));
+}
+
+TEST_CASE("Digital Signature Parameter Encryption p_data NULL", "[hw_crypto]")
+{
+    esp_ds_data_t data;
+    const char iv [32];
+    const char key [32];
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_encrypt_params(&data, iv, NULL, key));
+}
+
+TEST_CASE("Digital Signature Parameter Encryption key NULL", "[hw_crypto]")
+{
+    esp_ds_data_t data;
+    const char iv [32];
+    esp_ds_p_data_t p_data;
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_encrypt_params(&data, iv, &p_data, NULL));
+}
+
+TEST_CASE("Digital Signature Parameter Encryption", "[hw_crypto]")
+{
+    for (int i = 0; i < NUM_CASES; i++) {
+        printf("Encrypting test case %d...\n", i);
+        const encrypt_testcase_t *t = &test_cases[i];
+        esp_ds_data_t result = { };
+        esp_ds_p_data_t p_data;
+
+        memcpy(p_data.Y, t->p_data.Y, 4096/8);
+        memcpy(p_data.M, t->p_data.M, 4096/8);
+        memcpy(p_data.Rb, t->p_data.Rb, 4096/8);
+        p_data.M_prime = t->p_data.M_prime;
+        p_data.length = t->p_data.length;
+
+        esp_err_t r = esp_ds_encrypt_params(&result, t->iv, &p_data,
+                                                  test_hmac_keys[t->hmac_key_idx]);
+        printf("Encrypting test case %d done\n", i);
+        TEST_ASSERT_EQUAL(ESP_OK, r);
+        TEST_ASSERT_EQUAL(t->p_data.length, result.rsa_length);
+        TEST_ASSERT_EQUAL_HEX8_ARRAY(t->iv, result.iv, ETS_DS_IV_LEN);
+        TEST_ASSERT_EQUAL_HEX8_ARRAY(t->expected_c, result.c, ETS_DS_C_LEN);
+    }
+}
+
+TEST_CASE("Digital Signature start Invalid message", "[hw_crypto]")
+{
+    esp_ds_data_t ds_data = { };
+    ds_data.rsa_length = ESP_DS_RSA_4096;
+    esp_ds_context_t *ctx;
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_start_sign(NULL, &ds_data, HMAC_KEY1, &ctx));
+}
+
+TEST_CASE("Digital Signature start Invalid data", "[hw_crypto]")
+{
+    const char *message = "test";
+    esp_ds_context_t *ctx;
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_start_sign(message, NULL, HMAC_KEY1, &ctx));
+}
+
+TEST_CASE("Digital Signature start Invalid context", "[hw_crypto]")
+{
+    esp_ds_data_t ds_data = {};
+    ds_data.rsa_length = ESP_DS_RSA_4096;
+    const char *message = "test";
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_start_sign(message, &ds_data, HMAC_KEY1, NULL));
+}
+
+TEST_CASE("Digital Signature RSA length 0", "[hw_crypto]")
+{
+    esp_ds_data_t ds_data = {};
+    ds_data.rsa_length = 0;
+    const char *message = "test";
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_start_sign(message, &ds_data, HMAC_KEY1, NULL));
+}
+
+TEST_CASE("Digital Signature RSA length too long", "[hw_crypto]")
+{
+    esp_ds_data_t ds_data = {};
+    ds_data.rsa_length = 128;
+    const char *message = "test";
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_start_sign(message, &ds_data, HMAC_KEY1, NULL));
+}
+
+TEST_CASE("Digital Signature start HMAC key out of range", "[hw_crypto]")
+{
+    esp_ds_data_t ds_data = {};
+    ds_data.rsa_length = ESP_DS_RSA_4096;
+    esp_ds_context_t *ctx;
+    const char *message = "test";
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_start_sign(message, &ds_data, HMAC_KEY5 + 1, &ctx));
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_start_sign(message, &ds_data, HMAC_KEY0 - 1, &ctx));
+}
+
+TEST_CASE("Digital Signature finish Invalid signature ptr", "[hw_crypto]")
+{
+    esp_ds_context_t *ctx = NULL;
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_finish_sign(NULL, ctx));
+}
+
+TEST_CASE("Digital Signature finish Invalid context", "[hw_crypto]")
+{
+    uint8_t signature_data [128 * 4];
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_finish_sign(signature_data, NULL));
+}
+
+TEST_CASE("Digital Signature Blocking Invalid message", "[hw_crypto]")
+{
+    esp_ds_data_t ds_data = { };
+    ds_data.rsa_length = ESP_DS_RSA_4096;
+    uint8_t signature_data [128 * 4];
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_sign(NULL, &ds_data, HMAC_KEY1, signature_data));
+}
+
+TEST_CASE("Digital Signature Blocking Invalid data", "[hw_crypto]")
+{
+    const char *message = "test";
+    uint8_t signature_data [128 * 4];
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_sign(message, NULL, HMAC_KEY1, signature_data));
+}
+
+TEST_CASE("Digital Signature Blocking Invalid signature ptr", "[hw_crypto]")
+{
+    esp_ds_data_t ds_data = {};
+    ds_data.rsa_length = ESP_DS_RSA_4096;
+    const char *message = "test";
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_sign(message, &ds_data, HMAC_KEY1, NULL));
+}
+
+TEST_CASE("Digital Signature Blocking RSA length 0", "[hw_crypto]")
+{
+    esp_ds_data_t ds_data = {};
+    ds_data.rsa_length = 0;
+    const char *message = "test";
+    uint8_t signature_data [128 * 4];
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_sign(message, &ds_data, HMAC_KEY1, signature_data));
+}
+
+TEST_CASE("Digital Signature Blocking RSA length too long", "[hw_crypto]")
+{
+    esp_ds_data_t ds_data = {};
+    ds_data.rsa_length = 128;
+    const char *message = "test";
+    uint8_t signature_data [128 * 4];
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_sign(message, &ds_data, HMAC_KEY1, signature_data));
+}
+
+TEST_CASE("Digital Signature Blocking HMAC key out of range", "[hw_crypto]")
+{
+    esp_ds_data_t ds_data = {};
+    ds_data.rsa_length = 127;
+    const char *message = "test";
+    uint8_t signature_data [128 * 4];
+
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_sign(message, &ds_data, HMAC_KEY5 + 1, signature_data));
+    TEST_ASSERT_EQUAL(ESP_ERR_INVALID_ARG, esp_ds_sign(message, &ds_data, HMAC_KEY0 - 1, signature_data));
+}
+
+#if CONFIG_IDF_ENV_FPGA
+
+static void burn_hmac_keys(void)
+{
+    printf("Burning %d HMAC keys to efuse...\n", NUM_HMAC_KEYS);
+    for (int i = 0; i < NUM_HMAC_KEYS; i++) {
+        // TODO: vary the purpose across the keys
+        ets_efuse_purpose_t purpose = ETS_EFUSE_KEY_PURPOSE_HMAC_DOWN_DIGITAL_SIGNATURE;
+
+        // starting from block 1, block 0 occupied with HMAC upstream test key
+        int ets_status = ets_efuse_write_key(ETS_EFUSE_BLOCK_KEY1 + i,
+                                             purpose,
+                                             test_hmac_keys[i], 32);
+
+        if (ets_status == ESP_OK) {
+            printf("written DS test key to block [%d]!\n", ETS_EFUSE_BLOCK_KEY1 + i);
+        } else {
+            printf("writing DS test key to block [%d] failed, maybe written already\n", ETS_EFUSE_BLOCK_KEY1 + i);
+        }
+    }
+}
+
+TEST_CASE("Digital Signature wrong HMAC key purpose (FPGA only)", "[hw_crypto]")
+{
+    esp_ds_data_t ds_data = {};
+    ds_data.rsa_length = ESP_DS_RSA_4096;
+    esp_ds_context_t *ctx;
+    const char *message = "test";
+
+    // HMAC fails in that case because it checks for the correct purpose
+    TEST_ASSERT_EQUAL(ESP_ERR_HW_CRYPTO_DS_HMAC_FAIL, esp_ds_start_sign(message, &ds_data, HMAC_KEY0, &ctx));
+}
+
+TEST_CASE("Digital Signature Blocking wrong HMAC key purpose (FPGA only)", "[hw_crypto]")
+{
+    esp_ds_data_t ds_data = {};
+    ds_data.rsa_length = ESP_DS_RSA_4096;
+    const char *message = "test";
+    uint8_t signature_data [128 * 4];
+
+    // HMAC fails in that case because it checks for the correct purpose
+    TEST_ASSERT_EQUAL(ESP_ERR_HW_CRYPTO_DS_HMAC_FAIL, esp_ds_sign(message, &ds_data, HMAC_KEY0, signature_data));
+}
+
+TEST_CASE("Digital Signature Operation (FPGA only)", "[hw_crypto]")
+{
+    burn_hmac_keys();
+
+    for (int i = 0; i < NUM_CASES; i++) {
+        printf("Running test case %d...\n", i);
+        const encrypt_testcase_t *t = &test_cases[i];
+
+        // copy encrypt parameter test case into ds_data structure
+        esp_ds_data_t ds_data = { };
+        memcpy(ds_data.iv, t->iv, ETS_DS_IV_LEN);
+        memcpy(ds_data.c, t->expected_c, ETS_DS_C_LEN);
+        ds_data.rsa_length = t->p_data.length;
+
+        for (int j = 0; j < NUM_MESSAGES; j++) {
+            uint8_t signature[4096/8] = { 0 };
+            printf(" ... message %d\n", j);
+            esp_ds_context_t *esp_ds_ctx;
+
+            esp_err_t ds_r = esp_ds_start_sign(test_messages[j],
+                    &ds_data,
+                    t->hmac_key_idx + 1,
+                    &esp_ds_ctx);
+            TEST_ASSERT_EQUAL(ESP_OK, ds_r);
+
+            ds_r = esp_ds_finish_sign(signature, esp_ds_ctx);
+            TEST_ASSERT_EQUAL(ESP_OK, ds_r);
+
+            TEST_ASSERT_EQUAL_HEX8_ARRAY(t->expected_results[j], signature, sizeof(signature));
+        }
+    }
+}
+
+TEST_CASE("Digital Signature Blocking Operation (FPGA only)", "[hw_crypto]")
+{
+    burn_hmac_keys();
+
+    for (int i = 0; i < NUM_CASES; i++) {
+        printf("Running test case %d...\n", i);
+        const encrypt_testcase_t *t = &test_cases[i];
+
+        // copy encrypt parameter test case into ds_data structure
+        esp_ds_data_t ds_data = { };
+        memcpy(ds_data.iv, t->iv, ETS_DS_IV_LEN);
+        memcpy(ds_data.c, t->expected_c, ETS_DS_C_LEN);
+        ds_data.rsa_length = t->p_data.length;
+
+        uint8_t signature[4096/8] = { 0 };
+        esp_ds_context_t *esp_ds_ctx;
+
+        esp_err_t ds_r = esp_ds_start_sign(test_messages[0],
+                &ds_data,
+                t->hmac_key_idx + 1,
+                &esp_ds_ctx);
+        TEST_ASSERT_EQUAL(ESP_OK, ds_r);
+
+        ds_r = esp_ds_finish_sign(signature, esp_ds_ctx);
+        TEST_ASSERT_EQUAL(ESP_OK, ds_r);
+
+        TEST_ASSERT_EQUAL_HEX8_ARRAY(t->expected_results[0], signature, sizeof(signature));
+    }
+}
+TEST_CASE("Digital Signature Invalid Data (FPGA only)", "[hw_crypto]")
+{
+    burn_hmac_keys();
+
+    // Set up a valid test case
+    const encrypt_testcase_t *t = &test_cases[0];
+    esp_ds_data_t ds_data = { };
+    memcpy(ds_data.iv, t->iv, ETS_DS_IV_LEN);
+    memcpy(ds_data.c, t->expected_c, ETS_DS_C_LEN);
+    ds_data.rsa_length = t->p_data.length;
+
+    uint8_t signature[4096/8] = { 0 };
+    const uint8_t zero[4096/8] = { 0 };
+
+    // Corrupt the IV one bit at a time, rerun and expect failure
+    for (int bit = 0; bit < 128; bit++) {
+        printf("Corrupting IV bit %d...\n", bit);
+        ds_data.iv[bit / 8] ^= 1 << (bit % 8);
+        esp_ds_context_t *esp_ds_ctx;
+
+        esp_err_t ds_r = esp_ds_start_sign(test_messages[0], &ds_data, t->hmac_key_idx + 1, &esp_ds_ctx);
+        TEST_ASSERT_EQUAL(ESP_OK, ds_r);
+        ds_r = esp_ds_finish_sign(signature, esp_ds_ctx);
+        TEST_ASSERT_EQUAL(ESP_ERR_HW_CRYPTO_DS_INVALID_DIGEST, ds_r);
+        TEST_ASSERT_EQUAL_HEX8_ARRAY(zero, signature, 4096/8);
+
+        ds_data.iv[bit / 8] ^= 1 << (bit % 8);
+    }
+
+    // Corrupt encrypted key data one bit at a time, rerun and expect failure
+    printf("Corrupting C...\n");
+    for (int bit = 0; bit < ETS_DS_C_LEN * 8; bit++) {
+        printf("Corrupting C bit %d...\n", bit);
+        ds_data.c[bit / 8] ^= 1 << (bit % 8);
+        esp_ds_context_t *esp_ds_ctx;
+
+        esp_err_t ds_r = esp_ds_start_sign(test_messages[0], &ds_data, t->hmac_key_idx + 1, &esp_ds_ctx);
+        TEST_ASSERT_EQUAL(ESP_OK, ds_r);
+        ds_r = esp_ds_finish_sign(signature, esp_ds_ctx);
+        TEST_ASSERT_EQUAL(ESP_ERR_HW_CRYPTO_DS_INVALID_DIGEST, ds_r);
+        TEST_ASSERT_EQUAL_HEX8_ARRAY(zero, signature, 4096/8);
+
+        ds_data.c[bit / 8] ^= 1 << (bit % 8);
+    }
+}
+
+#endif // CONFIG_IDF_ENV_FPGA
+
+#endif // CONFIG_IDF_TARGET_ESP32S2

components/esp32s2/test/test_hmac.c

@@ -1,3 +1,17 @@
+// Copyright 2020 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 #include "esp_hmac.h"
 #include "unity.h"
 

components/esp_common/src/esp_err_to_name.c

@@ -5,6 +5,9 @@
 #if __has_include("soc/soc.h")
 #include "soc/soc.h"
 #endif
+#if __has_include("esp_ds.h")
+#include "esp_ds.h"
+#endif
 #if __has_include("esp_efuse.h")
 #include "esp_efuse.h"
 #endif
@@ -676,6 +679,23 @@ static const esp_err_msg_t esp_err_msg_table[] = {
 #   endif
 #   ifdef      ESP_ERR_HTTPD_TASK
     ERR_TBL_IT(ESP_ERR_HTTPD_TASK),                             /* 45064 0xb008 Failed to launch server task/thread */
+#   endif
+    // components/esp32s2/include/esp_ds.h
+#   ifdef      ESP_ERR_HW_CRYPTO_DS_BASE
+    ERR_TBL_IT(ESP_ERR_HW_CRYPTO_DS_BASE),                      /* 49152 0xc000 Starting number of HW cryptography
+                                                                                module error codes */
+#   endif
+#   ifdef      ESP_ERR_HW_CRYPTO_DS_HMAC_FAIL
+    ERR_TBL_IT(ESP_ERR_HW_CRYPTO_DS_HMAC_FAIL),                 /* 49153 0xc001 HMAC peripheral problem */
+#   endif
+#   ifdef      ESP_ERR_HW_CRYPTO_DS_INVALID_KEY
+    ERR_TBL_IT(ESP_ERR_HW_CRYPTO_DS_INVALID_KEY),               /* 49154 0xc002 */
+#   endif
+#   ifdef      ESP_ERR_HW_CRYPTO_DS_INVALID_DIGEST
+    ERR_TBL_IT(ESP_ERR_HW_CRYPTO_DS_INVALID_DIGEST),            /* 49156 0xc004 */
+#   endif
+#   ifdef      ESP_ERR_HW_CRYPTO_DS_INVALID_PADDING
+    ERR_TBL_IT(ESP_ERR_HW_CRYPTO_DS_INVALID_PADDING),           /* 49157 0xc005 */
 #   endif
 };
 #endif //CONFIG_ESP_ERR_TO_NAME_LOOKUP

tools/ci/config/target-test.yml

@@ -495,7 +495,7 @@ UT_034:
 
 UT_035:
   extends: .unit_test_s2_template
-  parallel: 31
+  parallel: 32
   tags:
     - ESP32S2_IDF
     - UT_T1_1