/** * (C) 2007-20 - ntop.org and contributors * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not see see * */ #include "cc20.h" #if defined (HAVE_OPENSSL_1_1) // openSSL 1.1 --------------------------------------------- /* get any erorr message out of openssl taken from https://en.wikibooks.org/wiki/OpenSSL/Error_handling */ static char *openssl_err_as_string (void) { BIO *bio = BIO_new (BIO_s_mem ()); ERR_print_errors (bio); char *buf = NULL; size_t len = BIO_get_mem_data (bio, &buf); char *ret = (char *) calloc (1, 1 + len); if(ret) memcpy (ret, buf, len); BIO_free (bio); return ret; } // encryption == decryption int cc20_crypt (unsigned char *out, const unsigned char *in, size_t in_len, const unsigned char *iv, cc20_context_t *ctx) { int evp_len; int evp_ciphertext_len; if(1 == EVP_EncryptInit_ex(ctx->ctx, ctx->cipher, NULL, ctx->key, iv)) { if(1 == EVP_CIPHER_CTX_set_padding(ctx->ctx, 0)) { if(1 == EVP_EncryptUpdate(ctx->ctx, out, &evp_len, in, in_len)) { evp_ciphertext_len = evp_len; if(1 == EVP_EncryptFinal_ex(ctx->ctx, out + evp_len, &evp_len)) { evp_ciphertext_len += evp_len; if(evp_ciphertext_len != in_len) traceEvent(TRACE_ERROR, "cc20_crypt openssl encryption: encrypted %u bytes where %u were expected", evp_ciphertext_len, in_len); } else traceEvent(TRACE_ERROR, "cc20_crypt openssl final encryption: %s", openssl_err_as_string()); } else traceEvent(TRACE_ERROR, "cc20_encrypt openssl encrpytion: %s", openssl_err_as_string()); } else traceEvent(TRACE_ERROR, "cc20_encrypt openssl padding setup: %s", openssl_err_as_string()); } else traceEvent(TRACE_ERROR, "cc20_encrypt openssl init: %s", openssl_err_as_string()); EVP_CIPHER_CTX_reset(ctx->ctx); return 0; } #else // plain C -------------------------------------------------------------------------- // taken (and modified) from https://github.com/Ginurx/chacha20-c (public domain) static void chacha20_init_block(cc20_context_t *ctx, const uint8_t nonce[]) { const uint8_t *magic_constant = (uint8_t*)"expand 32-byte k"; memcpy(&(ctx->state[0]), magic_constant, 16); memcpy (&(ctx->state[4]), ctx->key, CC20_KEY_BYTES); memcpy(&(ctx->state[12]), nonce, CC20_IV_SIZE); } #define ROL32(x,r) (((x)<<(r))|((x)>>(32-(r)))) #define CHACHA20_QUARTERROUND(x, a, b, c, d) \ x[a] += x[b]; x[d] = ROL32(x[d] ^ x[a], 16); \ x[c] += x[d]; x[b] = ROL32(x[b] ^ x[c], 12); \ x[a] += x[b]; x[d] = ROL32(x[d] ^ x[a], 8); \ x[c] += x[d]; x[b] = ROL32(x[b] ^ x[c], 7) #define CHACHA20_DOUBLE_ROUND \ CHACHA20_QUARTERROUND(ctx->keystream32, 0, 4, 8, 12); \ CHACHA20_QUARTERROUND(ctx->keystream32, 1, 5, 9, 13); \ CHACHA20_QUARTERROUND(ctx->keystream32, 2, 6, 10, 14); \ CHACHA20_QUARTERROUND(ctx->keystream32, 3, 7, 11, 15); \ CHACHA20_QUARTERROUND(ctx->keystream32, 0, 5, 10, 15); \ CHACHA20_QUARTERROUND(ctx->keystream32, 1, 6, 11, 12); \ CHACHA20_QUARTERROUND(ctx->keystream32, 2, 7, 8, 13); \ CHACHA20_QUARTERROUND(ctx->keystream32, 3, 4, 9, 14) static void chacha20_block_next(cc20_context_t *ctx) { int i; for(i = 0; i < 16; i++) ctx->keystream32[i] = ctx->state[i]; // 10 double rounds CHACHA20_DOUBLE_ROUND; CHACHA20_DOUBLE_ROUND; CHACHA20_DOUBLE_ROUND; CHACHA20_DOUBLE_ROUND; CHACHA20_DOUBLE_ROUND; CHACHA20_DOUBLE_ROUND; CHACHA20_DOUBLE_ROUND; CHACHA20_DOUBLE_ROUND; CHACHA20_DOUBLE_ROUND; CHACHA20_DOUBLE_ROUND; for(i = 0; i < 16; i++) ctx->keystream32[i] += ctx->state[i]; uint32_t *counter = ctx->state + 12; // increment counter, make sure it is little endian in memory uint32_t c = le32toh(counter[0]); counter[0] = htole32(++c); if(0 == counter[0]) { // wrap around occured, increment higher 32 bits of counter // unlikely with 1,500 byte sized packets c = le32toh(counter[1]); counter[1] = htole32(++c); if(0 == counter[1]) { // very unlikely c = le32toh(counter[2]); counter[2] = htole32(++c); if(0 == counter[2]) { // extremely unlikely c = le32toh(counter[3]); counter[3] = htole32(++c); } } } } static void chacha20_init_context(cc20_context_t *ctx, const uint8_t *nonce) { chacha20_init_block(ctx, nonce); ctx->position = 64; } int cc20_crypt (unsigned char *out, const unsigned char *in, size_t in_len, const unsigned char *iv, cc20_context_t *ctx) { chacha20_init_context(ctx, iv); uint8_t *keystream8 = (uint8_t*)ctx->keystream32; for(size_t i = 0; i < in_len; i++) { if(ctx->position >= 64) { chacha20_block_next(ctx); ctx->position = 0; } out[i] = in[i] ^ keystream8[ctx->position]; ctx->position++; } } #endif // openSSL 1.1, plain C ------------------------------------------------------------ int cc20_init (const unsigned char *key, cc20_context_t **ctx) { // allocate context... *ctx = (cc20_context_t*) calloc(1, sizeof(cc20_context_t)); if (!(*ctx)) return -1; #if defined (HAVE_OPENSSL_1_1) if(!((*ctx)->ctx = EVP_CIPHER_CTX_new())) { traceEvent(TRACE_ERROR, "cc20_init openssl's evp_* encryption context creation failed: %s", openssl_err_as_string()); return -1; } (*ctx)->cipher = EVP_chacha20(); #endif memcpy((*ctx)->key, key, CC20_KEY_BYTES); return 0; } int cc20_deinit (cc20_context_t *ctx) { #if defined (HAVE_OPENSSL_1_1) if (ctx->ctx) EVP_CIPHER_CTX_free(ctx->ctx); #endif return 0; }