Add counter mode encryption.

diff --git a/src/openssl/cipher.c b/src/openssl/cipher.c
index 743449a..63892f3 100644 (file)
--- a/src/openssl/cipher.c
+++ b/src/openssl/cipher.c
@@ -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;

diff --git a/src/openssl/cipher.h b/src/openssl/cipher.h
index 380384a..589ec4c 100644 (file)
--- a/src/openssl/cipher.h
+++ b/src/openssl/cipher.h
@@ -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 *);