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Diffstat (limited to 'programs/cipher/cipher_aead_demo.c')
| -rw-r--r-- | programs/cipher/cipher_aead_demo.c | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/programs/cipher/cipher_aead_demo.c b/programs/cipher/cipher_aead_demo.c new file mode 100644 index 00000000000..853ec202c6f --- /dev/null +++ b/programs/cipher/cipher_aead_demo.c @@ -0,0 +1,259 @@ +/** + * Cipher API multi-part AEAD demonstration. + * + * This program AEAD-encrypts a message, using the algorithm and key size + * specified on the command line, using the multi-part API. + * + * It comes with a companion program psa/aead_demo.c, which does the same + * operations with the PSA Crypto API. The goal is that comparing the two + * programs will help people migrating to the PSA Crypto API. + * + * When used with multi-part AEAD operations, the `mbedtls_cipher_context` + * serves a triple purpose (1) hold the key, (2) store the algorithm when no + * operation is active, and (3) save progress information for the current + * operation. With PSA those roles are held by disinct objects: (1) a + * psa_key_id_t to hold the key, a (2) psa_algorithm_t to represent the + * algorithm, and (3) a psa_operation_t for multi-part progress. + * + * On the other hand, with PSA, the algorithms encodes the desired tag length; + * with Cipher the desired tag length needs to be tracked separately. + * + * This program and its companion psa/aead_demo.c illustrate this by doing the + * same sequence of multi-part AEAD computation with both APIs; looking at the + * two side by side should make the differences and similarities clear. + */ + +/* + * Copyright The Mbed TLS Contributors + * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later + */ + +/* First include Mbed TLS headers to get the Mbed TLS configuration and + * platform definitions that we'll use in this program. Also include + * standard C headers for functions we'll use here. */ +#include "mbedtls/build_info.h" + +#include "mbedtls/cipher.h" + +#include <stdlib.h> +#include <stdio.h> +#include <string.h> + +/* If the build options we need are not enabled, compile a placeholder. */ +#if !defined(MBEDTLS_CIPHER_C) || \ + !defined(MBEDTLS_AES_C) || !defined(MBEDTLS_GCM_C) || \ + !defined(MBEDTLS_CHACHAPOLY_C) +int main(void) +{ + printf("MBEDTLS_MD_C and/or " + "MBEDTLS_AES_C and/or MBEDTLS_GCM_C and/or " + "MBEDTLS_CHACHAPOLY_C not defined\r\n"); + return 0; +} +#else + +/* The real program starts here. */ + +const char usage[] = + "Usage: cipher_aead_demo [aes128-gcm|aes256-gcm|aes128-gcm_8|chachapoly]"; + +/* Dummy data for encryption: IV/nonce, additional data, 2-part message */ +const unsigned char iv1[12] = { 0x00 }; +const unsigned char add_data1[] = { 0x01, 0x02 }; +const unsigned char msg1_part1[] = { 0x03, 0x04 }; +const unsigned char msg1_part2[] = { 0x05, 0x06, 0x07 }; + +/* Dummy data (2nd message) */ +const unsigned char iv2[12] = { 0x10 }; +const unsigned char add_data2[] = { 0x11, 0x12 }; +const unsigned char msg2_part1[] = { 0x13, 0x14 }; +const unsigned char msg2_part2[] = { 0x15, 0x16, 0x17 }; + +/* Maximum total size of the messages */ +#define MSG1_SIZE (sizeof(msg1_part1) + sizeof(msg1_part2)) +#define MSG2_SIZE (sizeof(msg2_part1) + sizeof(msg2_part2)) +#define MSG_MAX_SIZE (MSG1_SIZE > MSG2_SIZE ? MSG1_SIZE : MSG2_SIZE) + +/* Dummy key material - never do this in production! + * 32-byte is enough to all the key size supported by this program. */ +const unsigned char key_bytes[32] = { 0x2a }; + +/* Print the contents of a buffer in hex */ +void print_buf(const char *title, unsigned char *buf, size_t len) +{ + printf("%s:", title); + for (size_t i = 0; i < len; i++) { + printf(" %02x", buf[i]); + } + printf("\n"); +} + +/* Run an Mbed TLS function and bail out if it fails. + * A string description of the error code can be recovered with: + * programs/util/strerror <value> */ +#define CHK(expr) \ + do \ + { \ + ret = (expr); \ + if (ret != 0) \ + { \ + printf("Error %d at line %d: %s\n", \ + ret, \ + __LINE__, \ + #expr); \ + goto exit; \ + } \ + } while (0) + +/* + * Prepare encryption material: + * - interpret command-line argument + * - set up key + * - outputs: context and tag length, which together hold all the information + */ +static int aead_prepare(const char *info, + mbedtls_cipher_context_t *ctx, + size_t *tag_len) +{ + int ret; + + /* Convert arg to type + tag_len */ + mbedtls_cipher_type_t type; + if (strcmp(info, "aes128-gcm") == 0) { + type = MBEDTLS_CIPHER_AES_128_GCM; + *tag_len = 16; + } else if (strcmp(info, "aes256-gcm") == 0) { + type = MBEDTLS_CIPHER_AES_256_GCM; + *tag_len = 16; + } else if (strcmp(info, "aes128-gcm_8") == 0) { + type = MBEDTLS_CIPHER_AES_128_GCM; + *tag_len = 8; + } else if (strcmp(info, "chachapoly") == 0) { + type = MBEDTLS_CIPHER_CHACHA20_POLY1305; + *tag_len = 16; + } else { + puts(usage); + return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA; + } + + /* Prepare context for the given type */ + CHK(mbedtls_cipher_setup(ctx, + mbedtls_cipher_info_from_type(type))); + + /* Import key */ + int key_len = mbedtls_cipher_get_key_bitlen(ctx); + CHK(mbedtls_cipher_setkey(ctx, key_bytes, key_len, MBEDTLS_ENCRYPT)); + +exit: + return ret; +} + +/* + * Print out some information. + * + * All of this information was present in the command line argument, but his + * function demonstrates how each piece can be recovered from (ctx, tag_len). + */ +static void aead_info(const mbedtls_cipher_context_t *ctx, size_t tag_len) +{ + mbedtls_cipher_type_t type = mbedtls_cipher_get_type(ctx); + const mbedtls_cipher_info_t *info = mbedtls_cipher_info_from_type(type); + const char *ciph = mbedtls_cipher_info_get_name(info); + int key_bits = mbedtls_cipher_get_key_bitlen(ctx); + mbedtls_cipher_mode_t mode = mbedtls_cipher_get_cipher_mode(ctx); + + const char *mode_str = mode == MBEDTLS_MODE_GCM ? "GCM" + : mode == MBEDTLS_MODE_CHACHAPOLY ? "ChachaPoly" + : "???"; + + printf("%s, %d, %s, %u\n", + ciph, key_bits, mode_str, (unsigned) tag_len); +} + +/* + * Encrypt a 2-part message. + */ +static int aead_encrypt(mbedtls_cipher_context_t *ctx, size_t tag_len, + const unsigned char *iv, size_t iv_len, + const unsigned char *ad, size_t ad_len, + const unsigned char *part1, size_t part1_len, + const unsigned char *part2, size_t part2_len) +{ + int ret; + size_t olen; +#define MAX_TAG_LENGTH 16 + unsigned char out[MSG_MAX_SIZE + MAX_TAG_LENGTH]; + unsigned char *p = out; + + CHK(mbedtls_cipher_set_iv(ctx, iv, iv_len)); + CHK(mbedtls_cipher_reset(ctx)); + CHK(mbedtls_cipher_update_ad(ctx, ad, ad_len)); + CHK(mbedtls_cipher_update(ctx, part1, part1_len, p, &olen)); + p += olen; + CHK(mbedtls_cipher_update(ctx, part2, part2_len, p, &olen)); + p += olen; + CHK(mbedtls_cipher_finish(ctx, p, &olen)); + p += olen; + CHK(mbedtls_cipher_write_tag(ctx, p, tag_len)); + p += tag_len; + + olen = p - out; + print_buf("out", out, olen); + +exit: + return ret; +} + +/* + * AEAD demo: set up key/alg, print out info, encrypt messages. + */ +static int aead_demo(const char *info) +{ + int ret = 0; + + mbedtls_cipher_context_t ctx; + size_t tag_len; + + mbedtls_cipher_init(&ctx); + + CHK(aead_prepare(info, &ctx, &tag_len)); + + aead_info(&ctx, tag_len); + + CHK(aead_encrypt(&ctx, tag_len, + iv1, sizeof(iv1), add_data1, sizeof(add_data1), + msg1_part1, sizeof(msg1_part1), + msg1_part2, sizeof(msg1_part2))); + CHK(aead_encrypt(&ctx, tag_len, + iv2, sizeof(iv2), add_data2, sizeof(add_data2), + msg2_part1, sizeof(msg2_part1), + msg2_part2, sizeof(msg2_part2))); + +exit: + mbedtls_cipher_free(&ctx); + + return ret; +} + + +/* + * Main function + */ +int main(int argc, char **argv) +{ + /* Check usage */ + if (argc != 2) { + puts(usage); + return 1; + } + + int ret; + + /* Run the demo */ + CHK(aead_demo(argv[1])); + +exit: + return ret == 0 ? EXIT_SUCCESS : EXIT_FAILURE; +} + +#endif |