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@ -35,7 +35,9 @@ |
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/* AES plaintext preamble */ |
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#define TRANSOP_AES_VER_SIZE 1 /* Support minor variants in encoding in one module. */ |
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#define TRANSOP_AES_IV_SEED_SIZE 8 /* size of transmitted random part of IV in bytes; leave it set to 8 for now */ |
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#define TRANSOP_AES_IV_SEED_SIZE 8 /* size of transmitted random part of IV in bytes; could range |
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* from 0=lowest security (constant IV) to 16=higest security |
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* (fully random IV); default=8 */ |
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#define TRANSOP_AES_IV_PADDING_SIZE (N2N_AES_IVEC_SIZE - TRANSOP_AES_IV_SEED_SIZE) |
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#define TRANSOP_AES_IV_KEY_BYTES (AES128_KEY_BYTES) /* use AES128 for IV encryption */ |
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#define TRANSOP_AES_PREAMBLE_SIZE (TRANSOP_AES_VER_SIZE + TRANSOP_AES_IV_SEED_SIZE) |
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@ -43,7 +45,7 @@ |
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typedef unsigned char n2n_aes_ivec_t[N2N_AES_IVEC_SIZE]; |
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typedef struct transop_aes { |
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#ifdef OPENSSL_1_1 |
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#ifdef HAVE_OPENSSL_1_1 |
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EVP_CIPHER_CTX *enc_ctx; /* openssl's reusable evp_* encryption context */ |
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EVP_CIPHER_CTX *dec_ctx; /* openssl's reusable evp_* decryption context */ |
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const EVP_CIPHER *cipher; /* cipher to use: e.g. EVP_aes_128_cbc */ |
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@ -61,7 +63,7 @@ typedef struct transop_aes { |
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static int transop_deinit_aes(n2n_trans_op_t *arg) { |
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transop_aes_t *priv = (transop_aes_t *)arg->priv; |
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#ifdef OPENSSL_1_1 |
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#ifdef HAVE_OPENSSL_1_1 |
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EVP_CIPHER_CTX_free(priv->enc_ctx); |
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EVP_CIPHER_CTX_free(priv->dec_ctx); |
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#endif |
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@ -74,10 +76,10 @@ static int transop_deinit_aes(n2n_trans_op_t *arg) { |
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/* ****************************************************** */ |
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#ifdef OPENSSL_1_1 |
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#ifdef HAVE_OPENSSL_1_1 |
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/* get any erorr message out of openssl
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taken from https://en.wikibooks.org/wiki/OpenSSL/Error_handling */
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char *openssl_err_as_string (void) { |
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static char *openssl_err_as_string (void) { |
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BIO *bio = BIO_new (BIO_s_mem ()); |
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ERR_print_errors (bio); |
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char *buf = NULL; |
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@ -94,12 +96,35 @@ char *openssl_err_as_string (void) { |
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/* ****************************************************** */ |
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static void set_aes_cbc_iv(transop_aes_t *priv, n2n_aes_ivec_t ivec, uint64_t iv_seed) { |
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/* convert a given number of bytes from memory to hex string; taken (and modified) from
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https://stackoverflow.com/questions/6357031/how-do-you-convert-a-byte-array-to-a-hexadecimal-string-in-c */
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const char* to_hex(unsigned char * in, size_t insz, char * out, size_t outsz) |
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{ |
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unsigned char * pin = in; |
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const char * hex = "0123456789abcdef"; |
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char * pout = out; |
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for(; pin < in+insz; pout +=2, pin++){ |
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pout[0] = hex[(*pin>>4) & 0xF]; |
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pout[1] = hex[ *pin & 0xF]; |
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if (pout + 2 - out > outsz){ |
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/* Better to truncate output string than overflow buffer */ |
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/* it would be still better to either return a status */ |
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/* or ensure the target buffer is large enough and it never happen */ |
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break; |
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} |
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} |
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pout[2] = 0; |
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return out; |
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} |
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/* ****************************************************** */ |
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static void set_aes_cbc_iv(transop_aes_t *priv, n2n_aes_ivec_t ivec, uint8_t * iv_seed) { |
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uint8_t iv_full[N2N_AES_IVEC_SIZE]; |
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/* Extend the seed to full block size with padding value */ |
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memcpy(iv_full, priv->iv_pad_val, TRANSOP_AES_IV_PADDING_SIZE); |
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memcpy(iv_full + TRANSOP_AES_IV_PADDING_SIZE, &iv_seed, TRANSOP_AES_IV_SEED_SIZE); |
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memcpy(iv_full + TRANSOP_AES_IV_PADDING_SIZE, iv_seed, TRANSOP_AES_IV_SEED_SIZE); |
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/* Encrypt the IV with secret key to make it unpredictable.
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* As discussed in https://github.com/ntop/n2n/issues/72, it's important to
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@ -115,7 +140,7 @@ static void set_aes_cbc_iv(transop_aes_t *priv, n2n_aes_ivec_t ivec, uint64_t iv |
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/** The aes packet format consists of:
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* |
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* - a 8-bit aes encoding version in clear text |
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* - a 64-bit random IV seed |
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* - a TRANSOP_AES_IV_SEED_SIZE-sized [bytes] random IV seed |
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* - encrypted payload. |
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* |
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* [V|II|DDDDDDDDDDDDDDDDDDDDD] |
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@ -135,7 +160,7 @@ static int transop_encode_aes(n2n_trans_op_t * arg, |
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if((in_len + TRANSOP_AES_PREAMBLE_SIZE) <= out_len) { |
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int len=-1; |
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size_t idx=0; |
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uint64_t iv_seed = 0; |
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uint8_t iv_seed[TRANSOP_AES_IV_SEED_SIZE]; |
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uint8_t padding = 0; |
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n2n_aes_ivec_t enc_ivec = {0}; |
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@ -144,12 +169,20 @@ static int transop_encode_aes(n2n_trans_op_t * arg, |
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/* Encode the aes format version. */ |
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encode_uint8(outbuf, &idx, N2N_AES_TRANSFORM_VERSION); |
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/* Generate and encode the IV seed.
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* Using two calls to rand() because RAND_MAX is usually < 64bit |
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* (e.g. linux) and sometimes < 32bit (e.g. Windows). |
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*/ |
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iv_seed = ((((uint64_t)rand() & 0xFFFFFFFF)) << 32) | rand(); |
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encode_buf(outbuf, &idx, &iv_seed, TRANSOP_AES_IV_SEED_SIZE); |
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/* Generate and encode the IV seed using as many calls to rand() as neccessary.
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* Note: ( N2N_AES_IV_SEED_SIZE % sizeof(rand_value) ) not neccessarily equals 0. */ |
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uint32_t rand_value; |
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int8_t i; |
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for (i = TRANSOP_AES_IV_SEED_SIZE; i >= sizeof(rand_value); i -= sizeof(rand_value)) { |
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rand_value = rand(); // CONCERN: rand() is not consideren cryptographicly secure, REPLACE later
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memcpy(iv_seed + TRANSOP_AES_IV_SEED_SIZE - i, &rand_value, sizeof(rand_value)); |
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} |
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/* Are there bytes left to fill? */ |
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if (i != 0) { |
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rand_value = rand(); // CONCERN: rand() is not consideren cryptographicly secure, REPLACE later
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memcpy(iv_seed, &rand_value, i); |
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} |
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encode_buf(outbuf, &idx, iv_seed, TRANSOP_AES_IV_SEED_SIZE); |
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/* Encrypt the assembly contents and write the ciphertext after the iv seed. */ |
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/* len is set to the length of the cipher plain text to be encrpyted
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@ -164,11 +197,13 @@ static int transop_encode_aes(n2n_trans_op_t * arg, |
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len2 = ((len / AES_BLOCK_SIZE) + 1) * AES_BLOCK_SIZE; /* Round up to next whole AES adding at least one byte. */ |
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padding = (len2-len); |
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assembly[len2 - 1] = padding; |
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traceEvent(TRACE_DEBUG, "padding = %u, seed = %016llx", padding, iv_seed); |
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char iv_seed_hex[2 * N2N_AES_IVEC_SIZE + 1]; |
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traceEvent(TRACE_DEBUG, "padding = %u, seed = 0x%s", padding, to_hex (iv_seed, TRANSOP_AES_IV_SEED_SIZE, iv_seed_hex, 2 * N2N_AES_IVEC_SIZE + 1) ); |
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set_aes_cbc_iv(priv, enc_ivec, iv_seed); |
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#ifdef OPENSSL_1_1 |
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#ifdef HAVE_OPENSSL_1_1 |
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EVP_CIPHER_CTX *ctx = priv->enc_ctx; |
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int evp_len; |
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int evp_ciphertext_len; |
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@ -229,7 +264,7 @@ static int transop_decode_aes(n2n_trans_op_t * arg, |
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size_t rem=in_len; |
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size_t idx=0; |
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uint8_t aes_enc_ver=0; |
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uint64_t iv_seed=0; |
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uint8_t iv_seed[TRANSOP_AES_IV_SEED_SIZE]; |
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/* Get the encoding version to make sure it is supported */ |
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decode_uint8(&aes_enc_ver, inbuf, &rem, &idx ); |
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@ -238,7 +273,8 @@ static int transop_decode_aes(n2n_trans_op_t * arg, |
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/* Get the IV seed */ |
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decode_buf((uint8_t *)&iv_seed, TRANSOP_AES_IV_SEED_SIZE, inbuf, &rem, &idx); |
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traceEvent(TRACE_DEBUG, "decode_aes %lu with seed %016llx", in_len, iv_seed); |
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char iv_seed_hex[2 * N2N_AES_IVEC_SIZE + 1]; |
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traceEvent(TRACE_DEBUG, "decode_aes %lu with seed 0x%s", in_len, to_hex (iv_seed, TRANSOP_AES_IV_SEED_SIZE, iv_seed_hex, 2 * N2N_AES_IVEC_SIZE + 1) ); |
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len = (in_len - TRANSOP_AES_PREAMBLE_SIZE); |
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@ -248,7 +284,7 @@ static int transop_decode_aes(n2n_trans_op_t * arg, |
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set_aes_cbc_iv(priv, dec_ivec, iv_seed); |
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#ifdef OPENSSL_1_1 |
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#ifdef HAVE_OPENSSL_1_1 |
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EVP_CIPHER_CTX *ctx = priv->dec_ctx; |
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int evp_len; |
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int evp_plaintext_len; |
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@ -319,7 +355,7 @@ static int setup_aes_key(transop_aes_t *priv, const uint8_t *key, ssize_t key_si |
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size_t key_mat_buf_length; |
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/* Clear out any old possibly longer key matter. */ |
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#ifdef OPENSSL_1_1 |
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#ifdef HAVE_OPENSSL_1_1 |
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memset(&(priv->key), 0, sizeof(priv->key) ); |
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#else |
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memset(&(priv->enc_key), 0, sizeof(priv->enc_key) ); |
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@ -344,14 +380,14 @@ static int setup_aes_key(transop_aes_t *priv, const uint8_t *key, ssize_t key_si |
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*/ |
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if(key_size >= 65) { |
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#ifdef OPENSSL_1_1 |
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#ifdef HAVE_OPENSSL_1_1 |
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priv->cipher = EVP_aes_256_cbc(); |
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#endif |
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aes_key_size_bytes = AES256_KEY_BYTES; |
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SHA512(key, key_size, key_mat_buf); |
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key_mat_buf_length = SHA512_DIGEST_LENGTH; |
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} else if(key_size >= 44) { |
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#ifdef OPENSSL_1_1 |
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#ifdef HAVE_OPENSSL_1_1 |
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priv->cipher = EVP_aes_192_cbc(); |
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#endif |
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aes_key_size_bytes = AES192_KEY_BYTES; |
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@ -360,7 +396,7 @@ static int setup_aes_key(transop_aes_t *priv, const uint8_t *key, ssize_t key_si |
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SHA256(key_mat_buf, SHA384_DIGEST_LENGTH, key_mat_buf + SHA384_DIGEST_LENGTH); |
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key_mat_buf_length = SHA384_DIGEST_LENGTH + SHA256_DIGEST_LENGTH; |
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} else { |
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#ifdef OPENSSL_1_1 |
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#ifdef HAVE_OPENSSL_1_1 |
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priv->cipher = EVP_aes_128_cbc(); |
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#endif |
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aes_key_size_bytes = AES128_KEY_BYTES; |
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@ -381,7 +417,7 @@ static int setup_aes_key(transop_aes_t *priv, const uint8_t *key, ssize_t key_si |
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/* setup of key, used for the CBC encryption */ |
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aes_key_size_bits = 8 * aes_key_size_bytes; |
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#ifdef OPENSSL_1_1 |
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#ifdef HAVE_OPENSSL_1_1 |
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memcpy (priv->key, key_mat_buf, aes_key_size_bytes); |
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#else |
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AES_set_encrypt_key(key_mat_buf, aes_key_size_bits, &(priv->enc_key)); |
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@ -425,7 +461,7 @@ int n2n_transop_aes_cbc_init(const n2n_edge_conf_t *conf, n2n_trans_op_t *ttt) { |
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} |
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ttt->priv = priv; |
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#ifdef OPENSSL_1_1 |
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#ifdef HAVE_OPENSSL_1_1 |
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/* Setup openssl's reusable evp_* contexts for encryption and decryption*/ |
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if(!(priv->enc_ctx = EVP_CIPHER_CTX_new())) { |
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traceEvent(TRACE_ERROR, "openssl's evp_* encryption context creation: %s\n", openssl_err_as_string()); |
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Logan oos Even
5 years ago
GitHub