grasshopper: Fix streaming for CTR mode

[openssl-gost/engine.git] / gost_grasshopper_cipher.c

diff --git a/gost_grasshopper_cipher.c b/gost_grasshopper_cipher.c
index b33fe53dca4ba3f7a2fdf24e3ebf5f84f80965b7..2cdf57eba611a5df84bae8e5f6e9f1899220baa4 100644 (file)
--- a/gost_grasshopper_cipher.c
+++ b/gost_grasshopper_cipher.c
@@ -138,8 +138,6 @@ static GRASSHOPPER_INLINE void gost_grasshopper_cipher_destroy_ctr(gost_grasshop
 
     grasshopper_zero128(&ctx->iv_buffer);
     grasshopper_zero128(&ctx->partial_buffer);
-
-    ctx->counter = 0;
 }
 
 int gost_grasshopper_cipher_init(EVP_CIPHER_CTX* ctx, const unsigned char* key,
@@ -210,12 +208,11 @@ GRASSHOPPER_INLINE int gost_grasshopper_cipher_init_ctr(EVP_CIPHER_CTX* ctx, con
     gost_grasshopper_cipher_ctx_ctr* c = EVP_CIPHER_CTX_get_cipher_data(ctx);
 
     c->c.type = GRASSHOPPER_CIPHER_CTR;
+    EVP_CIPHER_CTX_set_num(ctx, 0);
 
     grasshopper_zero128(&c->iv_buffer);
     grasshopper_zero128(&c->partial_buffer);
 
-    c->counter = 0;
-
     return gost_grasshopper_cipher_init(ctx, key, iv, enc);
 }
 
@@ -283,28 +280,50 @@ int gost_grasshopper_cipher_do_cbc(EVP_CIPHER_CTX* ctx, unsigned char* out,
     return 1;
 }
 
+/* increment counter (128-bit int) by 1 */
+static void ctr128_inc(unsigned char *counter)
+{
+    unsigned int n = 16;
+    unsigned char c;
+
+    do {
+        --n;
+        c = counter[n];
+        ++c;
+        counter[n] = c;
+        if (c) return;
+    } while (n);
+}
+
 int gost_grasshopper_cipher_do_ctr(EVP_CIPHER_CTX* ctx, unsigned char* out,
                                           const unsigned char* in, size_t inl) {
     gost_grasshopper_cipher_ctx_ctr* c = (gost_grasshopper_cipher_ctx_ctr*) EVP_CIPHER_CTX_get_cipher_data(ctx);
     unsigned char* iv = EVP_CIPHER_CTX_iv_noconst(ctx);
     const unsigned char* current_in = in;
     unsigned char* current_out = out;
-    size_t blocks = inl / GRASSHOPPER_BLOCK_SIZE;
     grasshopper_w128_t* currentInputBlock;
     grasshopper_w128_t* currentOutputBlock;
+    unsigned int n = EVP_CIPHER_CTX_num(ctx);
     size_t lasted;
     size_t i;
 
+    while (n && inl) {
+       *(current_out++) = *(current_in++) ^ c->partial_buffer.b[n];
+       --inl;
+       n = (n + 1) % GRASSHOPPER_BLOCK_SIZE;
+    }
+    EVP_CIPHER_CTX_set_num(ctx, n);
+    size_t blocks = inl / GRASSHOPPER_BLOCK_SIZE;
+
     memcpy(&c->iv_buffer, iv, 8);
 
     // full parts
     for (i = 0; i < blocks; i++) {
         currentInputBlock = (grasshopper_w128_t*) current_in;
         currentOutputBlock = (grasshopper_w128_t*) current_out;
-        memcpy(c->iv_buffer.b + 8, &c->counter, 8);
         grasshopper_encrypt_block(&c->c.encrypt_round_keys, &c->iv_buffer, currentOutputBlock, &c->c.buffer);
         grasshopper_append128(currentOutputBlock, currentInputBlock);
-        c->counter += 1;
+        ctr128_inc(c->iv_buffer.b);
         current_in += GRASSHOPPER_BLOCK_SIZE;
         current_out += GRASSHOPPER_BLOCK_SIZE;
     }
@@ -314,12 +333,12 @@ int gost_grasshopper_cipher_do_ctr(EVP_CIPHER_CTX* ctx, unsigned char* out,
     if (lasted > 0) {
         currentInputBlock = (grasshopper_w128_t*) current_in;
         currentOutputBlock = (grasshopper_w128_t*) current_out;
-        memcpy(c->iv_buffer.b + 8, &c->counter, 8);
         grasshopper_encrypt_block(&c->c.encrypt_round_keys, &c->iv_buffer, &c->partial_buffer, &c->c.buffer);
         for (i = 0; i < lasted; i++) {
             currentOutputBlock->b[i] = c->partial_buffer.b[i] ^ currentInputBlock->b[i];
         }
-        c->counter += 1;
+       EVP_CIPHER_CTX_set_num(ctx, i);
+        ctr128_inc(c->iv_buffer.b);
     }
 
     return 1;
@@ -526,7 +545,6 @@ int gost_grasshopper_cipher_cleanup(EVP_CIPHER_CTX* ctx) {
 int gost_grasshopper_set_asn1_parameters(EVP_CIPHER_CTX* ctx, ASN1_TYPE* params) {
     int len = 0;
     unsigned char* buf = NULL;
-    unsigned char* p = NULL;
     ASN1_OCTET_STRING* os = NULL;
 
     os = ASN1_OCTET_STRING_new();