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Add counter mode encryption.

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This commit is contained in:
Guus Sliepen 2011-10-06 09:33:09 +02:00
parent 67ff81ec16
commit a0f795ff5b
2 changed files with 65 additions and 1 deletions
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63
src/openssl/cipher.c
View file

@ -26,6 +26,12 @@
#include "logger.h"
#include "xalloc.h"
typedef struct cipher_counter {
unsigned char counter[EVP_MAX_IV_LENGTH];
unsigned char block[EVP_MAX_IV_LENGTH];
int n;
} cipher_counter_t;
static bool cipher_open(cipher_t *cipher) {
EVP_CIPHER_CTX_init(&cipher->ctx);
@ -59,10 +65,14 @@ bool cipher_open_blowfish_ofb(cipher_t *cipher) {
void cipher_close(cipher_t *cipher) {
EVP_CIPHER_CTX_cleanup(&cipher->ctx);
if(cipher->counter) {
free(cipher->counter);
cipher->counter = 0;
}
}
size_t cipher_keylength(const cipher_t *cipher) {
return cipher->cipher->key_len + cipher->cipher->iv_len;
return cipher->cipher->key_len + cipher->cipher->block_size;
}
bool cipher_set_key(cipher_t *cipher, void *key, bool encrypt) {
@ -95,6 +105,57 @@ bool cipher_set_key_from_rsa(cipher_t *cipher, void *key, size_t len, bool encry
return false;
}
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(LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
return false;
}
if(!cipher->counter)
cipher->counter = xmalloc_and_zero(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_counter_xor(cipher_t *cipher, const void *indata, size_t inlen, void *outdata) {
if(!cipher->counter) {
logger(LOG_ERR, "Counter not initialized");
return false;
}
const unsigned char *in = indata;
unsigned char *out = outdata;
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(LOG_ERR, "Error while encrypting: %s", ERR_error_string(ERR_get_error(), NULL));
return false;
}
// Increase the counter value
for(int i = 0; i < cipher->cipher->block_size; i++)
if(++cipher->counter->counter[i])
break;
}
*out++ = *in++ ^ cipher->counter->counter[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;

3
src/openssl/cipher.h
View file

@ -29,6 +29,7 @@
typedef struct cipher {
EVP_CIPHER_CTX ctx;
const EVP_CIPHER *cipher;
struct cipher_counter *counter;
} cipher_t;
extern bool cipher_open_by_name(cipher_t *, const char *);
@ -38,8 +39,10 @@ extern void cipher_close(cipher_t *);
extern size_t cipher_keylength(const cipher_t *);
extern bool cipher_set_key(cipher_t *, void *, bool);
extern bool cipher_set_key_from_rsa(cipher_t *, void *, size_t, bool);
extern bool cipher_set_counter_key(cipher_t *, void *);
extern bool cipher_encrypt(cipher_t *, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool);
extern bool cipher_decrypt(cipher_t *, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool);
extern bool cipher_counter_xor(cipher_t *, const void *indata, size_t inlen, void *outdata);
extern int cipher_get_nid(const cipher_t *);
extern bool cipher_active(const cipher_t *);