/*
cipher.c -- Symmetric block cipher handling
- Copyright (C) 2007-2013 Guus Sliepen <guus@tinc-vpn.org>
+ Copyright (C) 2007-2022 Guus Sliepen <guus@tinc-vpn.org>
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
#include "../system.h"
-#include <openssl/rand.h>
#include <openssl/err.h>
#include <openssl/evp.h>
+#include "log.h"
+#include "cipher.h"
#include "../cipher.h"
#include "../logger.h"
-#include "../xalloc.h"
-
-struct cipher {
- EVP_CIPHER_CTX ctx;
- const EVP_CIPHER *cipher;
- struct cipher_counter *counter;
-};
-
-typedef struct cipher_counter {
- unsigned char counter[CIPHER_MAX_IV_SIZE];
- unsigned char block[CIPHER_MAX_IV_SIZE];
- int n;
-} cipher_counter_t;
-
-static cipher_t *cipher_open(const EVP_CIPHER *evp_cipher) {
- cipher_t *cipher = xzalloc(sizeof *cipher);
+
+typedef int (enc_init_t)(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher, ENGINE *impl, const unsigned char *key, const unsigned char *iv);
+typedef int (enc_update_t)(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl, const unsigned char *in, int inl);
+typedef int (enc_final_t)(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
+
+static void cipher_open(cipher_t *cipher, const EVP_CIPHER *evp_cipher) {
cipher->cipher = evp_cipher;
- EVP_CIPHER_CTX_init(&cipher->ctx);
+ cipher->ctx = EVP_CIPHER_CTX_new();
- return cipher;
+ if(!cipher->ctx) {
+ abort();
+ }
}
-cipher_t *cipher_open_by_name(const char *name) {
+bool cipher_open_by_name(cipher_t *cipher, const char *name) {
const EVP_CIPHER *evp_cipher = EVP_get_cipherbyname(name);
+
if(!evp_cipher) {
logger(DEBUG_ALWAYS, LOG_ERR, "Unknown cipher name '%s'!", name);
- return NULL;
+ return false;
}
- return cipher_open(evp_cipher);
+ cipher_open(cipher, evp_cipher);
+ return true;
}
-cipher_t *cipher_open_by_nid(int nid) {
+bool cipher_open_by_nid(cipher_t *cipher, int nid) {
const EVP_CIPHER *evp_cipher = EVP_get_cipherbynid(nid);
+
if(!evp_cipher) {
logger(DEBUG_ALWAYS, LOG_ERR, "Unknown cipher nid %d!", nid);
- return NULL;
+ return false;
}
- return cipher_open(evp_cipher);
-}
-
-cipher_t *cipher_open_blowfish_ofb(void) {
- return cipher_open(EVP_bf_ofb());
+ cipher_open(cipher, evp_cipher);
+ return true;
}
void cipher_close(cipher_t *cipher) {
- if(!cipher)
+ if(!cipher) {
return;
+ }
+
+ if(cipher->ctx) {
+ EVP_CIPHER_CTX_free(cipher->ctx);
+ }
- EVP_CIPHER_CTX_cleanup(&cipher->ctx);
- free(cipher->counter);
- free(cipher);
+ memset(cipher, 0, sizeof(*cipher));
}
size_t cipher_keylength(const cipher_t *cipher) {
- if(!cipher || !cipher->cipher)
+ if(!cipher || !cipher->cipher) {
return 0;
+ }
- return cipher->cipher->key_len + cipher->cipher->block_size;
+ return EVP_CIPHER_key_length(cipher->cipher) + EVP_CIPHER_iv_length(cipher->cipher);
}
-bool cipher_set_key(cipher_t *cipher, void *key, bool encrypt) {
- bool result;
+uint64_t cipher_budget(const cipher_t *cipher) {
+ /* Hopefully some failsafe way to calculate the maximum amount of bytes to
+ send/receive with a given cipher before we might run into birthday paradox
+ attacks. Because we might use different modes, the block size of the mode
+ might be 1 byte. In that case, use the IV length. Ensure the whole thing
+ is limited to what can be represented with a 64 bits integer.
+ */
+
+ if(!cipher || !cipher->cipher) {
+ return UINT64_MAX; // NULL cipher
+ }
- if(encrypt)
- result = EVP_EncryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, (unsigned char *)key + cipher->cipher->key_len);
- else
- result = EVP_DecryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, (unsigned char *)key + cipher->cipher->key_len);
+ int ivlen = EVP_CIPHER_iv_length(cipher->cipher);
+ int blklen = EVP_CIPHER_block_size(cipher->cipher);
+ int len = blklen > 1 ? blklen : ivlen > 1 ? ivlen : 8;
+ int bits = len * 4 - 1;
+ return bits < 64 ? UINT64_C(1) << bits : UINT64_MAX;
+}
- if(result)
- return true;
+size_t cipher_blocksize(const cipher_t *cipher) {
+ if(!cipher || !cipher->cipher) {
+ return 1;
+ }
- logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
- return false;
+ return EVP_CIPHER_block_size(cipher->cipher);
}
-bool cipher_set_key_from_rsa(cipher_t *cipher, void *key, size_t len, bool encrypt) {
+static bool cipher_init_ctx(cipher_t *cipher, bool encrypt, const unsigned char *key, const unsigned char *iv) {
bool result;
- if(encrypt)
- result = EVP_EncryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key + len - cipher->cipher->key_len, (unsigned char *)key + len - cipher->cipher->iv_len - cipher->cipher->key_len);
- else
- result = EVP_DecryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key + len - cipher->cipher->key_len, (unsigned char *)key + len - cipher->cipher->iv_len - cipher->cipher->key_len);
+ if(encrypt) {
+ result = EVP_EncryptInit_ex(cipher->ctx, cipher->cipher, NULL, key, iv);
+ } else {
+ result = EVP_DecryptInit_ex(cipher->ctx, cipher->cipher, NULL, key, iv);
+ }
- if(result)
+ if(result) {
return true;
+ }
- logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
+ openssl_err("set key");
return false;
}
-bool cipher_set_counter(cipher_t *cipher, const void *counter, size_t len) {
- if(len > cipher->cipher->block_size - 4) {
- logger(DEBUG_ALWAYS, LOG_ERR, "Counter too long");
- abort();
- }
-
- memcpy(cipher->counter->counter + cipher->cipher->block_size - len, counter, len);
- memset(cipher->counter->counter, 0, 4);
- cipher->counter->n = 0;
-
- return true;
+bool cipher_set_key(cipher_t *cipher, void *key, bool encrypt) {
+ unsigned char *iv = (unsigned char *)key + EVP_CIPHER_key_length(cipher->cipher);
+ return cipher_init_ctx(cipher, encrypt, key, iv);
}
-bool cipher_set_counter_key(cipher_t *cipher, void *key) {
- int result = EVP_EncryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, NULL);
- if(!result) {
- logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
- return false;
- }
-
- if(!cipher->counter)
- cipher->counter = xzalloc(sizeof *cipher->counter);
- else
- cipher->counter->n = 0;
-
- memcpy(cipher->counter->counter, (unsigned char *)key + cipher->cipher->key_len, cipher->cipher->block_size);
-
- return true;
+bool cipher_set_key_from_rsa(cipher_t *cipher, void *key, size_t len, bool encrypt) {
+ unsigned char *k = (unsigned char *)key + len - EVP_CIPHER_key_length(cipher->cipher);
+ unsigned char *iv = k - EVP_CIPHER_iv_length(cipher->cipher);
+ return cipher_init_ctx(cipher, encrypt, k, iv);
}
-bool cipher_counter_xor(cipher_t *cipher, const void *indata, size_t inlen, void *outdata) {
- if(!cipher->counter) {
- logger(DEBUG_ALWAYS, LOG_ERR, "Counter not initialized");
- return false;
- }
-
- const unsigned char *in = indata;
- unsigned char *out = outdata;
+static bool cipher_encrypt_decrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot,
+ enc_init_t init, enc_update_t update, enc_final_t final) {
+ if(oneshot) {
+ int len, pad;
- while(inlen--) {
- // Encrypt the new counter value if we need it
- if(!cipher->counter->n) {
- int len;
- if(!EVP_EncryptUpdate(&cipher->ctx, cipher->counter->block, &len, cipher->counter->counter, cipher->cipher->block_size)) {
- logger(DEBUG_ALWAYS, LOG_ERR, "Error while encrypting: %s", ERR_error_string(ERR_get_error(), NULL));
- return false;
+ if(init(cipher->ctx, NULL, NULL, NULL, NULL)
+ && update(cipher->ctx, (unsigned char *)outdata, &len, indata, (int)inlen)
+ && final(cipher->ctx, (unsigned char *)outdata + len, &pad)) {
+ if(outlen) {
+ *outlen = len + pad;
}
- // Increase the counter value
- for(int i = 0; i < cipher->cipher->block_size; i++)
- if(++cipher->counter->counter[i])
- break;
- }
-
- *out++ = *in++ ^ cipher->counter->block[cipher->counter->n++];
-
- if(cipher->counter->n >= cipher->cipher->block_size)
- cipher->counter->n = 0;
- }
-
- return true;
-}
-
-
-bool cipher_encrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
- if(oneshot) {
- int len, pad;
- if(EVP_EncryptInit_ex(&cipher->ctx, NULL, NULL, NULL, NULL)
- && EVP_EncryptUpdate(&cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
- && EVP_EncryptFinal(&cipher->ctx, (unsigned char *)outdata + len, &pad)) {
- if(outlen) *outlen = len + pad;
return true;
}
} else {
int len;
- if(EVP_EncryptUpdate(&cipher->ctx, outdata, &len, indata, inlen)) {
- if(outlen) *outlen = len;
+
+ if(update(cipher->ctx, outdata, &len, indata, (int)inlen)) {
+ if(outlen) {
+ *outlen = len;
+ }
+
return true;
}
}
- logger(DEBUG_ALWAYS, LOG_ERR, "Error while encrypting: %s", ERR_error_string(ERR_get_error(), NULL));
+ openssl_err("encrypt or decrypt data");
return false;
}
-bool cipher_decrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
- if(oneshot) {
- int len, pad;
- if(EVP_DecryptInit_ex(&cipher->ctx, NULL, NULL, NULL, NULL)
- && EVP_DecryptUpdate(&cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
- && EVP_DecryptFinal(&cipher->ctx, (unsigned char *)outdata + len, &pad)) {
- if(outlen) *outlen = len + pad;
- return true;
- }
- } else {
- int len;
- if(EVP_EncryptUpdate(&cipher->ctx, outdata, &len, indata, inlen)) {
- if(outlen) *outlen = len;
- return true;
- }
- }
+bool cipher_encrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
+ return cipher_encrypt_decrypt(cipher, indata, inlen, outdata, outlen, oneshot,
+ EVP_EncryptInit_ex, EVP_EncryptUpdate, EVP_EncryptFinal_ex);
+}
- logger(DEBUG_ALWAYS, LOG_ERR, "Error while decrypting: %s", ERR_error_string(ERR_get_error(), NULL));
- return false;
+bool cipher_decrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
+ return cipher_encrypt_decrypt(cipher, indata, inlen, outdata, outlen, oneshot,
+ EVP_DecryptInit_ex, EVP_DecryptUpdate, EVP_DecryptFinal_ex);
}
int cipher_get_nid(const cipher_t *cipher) {
- if(!cipher || !cipher->cipher)
+ if(!cipher || !cipher->cipher) {
return 0;
+ }
- return cipher->cipher->nid;
+ return EVP_CIPHER_nid(cipher->cipher);
}
bool cipher_active(const cipher_t *cipher) {
- return cipher && cipher->cipher && cipher->cipher->nid != 0;
+ return cipher && cipher->cipher && EVP_CIPHER_nid(cipher->cipher) != 0;
}