Kexp/Kimp15 implementation, initial commmit.

1 files changed, 80 insertions, 0 deletions

diff --git a/gost_keyexpimp.c b/gost_keyexpimp.c
new file mode 100644
index 0000000..ba19245
--- /dev/null
+++ b/gost_keyexpimp.c
@@ -0,0 +1,80 @@
+#include <string.h>
+#include <openssl/evp.h>
+
+#include "gost_lcl.h"
+#include "e_gost_err.h"
+
+/*
+ * Function expects that out is a preallocated buffer of length
+ * defined as sum of shared_len and mac length defined by mac_nid
+ * */
+int gost_kexp15(const unsigned char *shared_key, const int shared_len, 
+    int cipher_nid, const unsigned char *cipher_key, const size_t cipher_key_len,
+    int mac_nid, unsigned char *mac_key, const size_t mac_key_len,
+    const char *iv, const size_t ivlen, 
+    unsigned char *out, int *out_len
+)
+{
+  /* out_len = key_len + mac_len */
+  unsigned char iv_full[16], mac_buf[8];
+  unsigned int mac_len;
+
+  EVP_CIPHER_CTX *ciph = NULL;
+  EVP_MD_CTX *mac = NULL;
+
+	int ret = 0;
+
+	/* we expect IV of half length */
+  memset(iv_full, 0, 16);
+  memcpy(iv_full, iv, ivlen);
+
+  mac = EVP_MD_CTX_new();
+	if (mac == NULL) {
+		GOSTerr(GOST_F_GOST_KEXP15, ERR_R_MALLOC_FAILURE);
+		goto err;
+	}
+
+  if(EVP_DigestInit_ex(mac, EVP_get_digestbynid(mac_nid), NULL) <= 0 
+	|| EVP_MD_CTX_ctrl(mac, EVP_MD_CTRL_SET_KEY, mac_key_len, mac_key) <= 0
+  || EVP_DigestUpdate(mac, shared_key, shared_len) <= 0
+  || EVP_DigestFinal_ex(mac, mac_buf, &mac_len) <= 0) {
+		GOSTerr(GOST_F_GOST_KEXP15, ERR_R_INTERNAL_ERROR);
+		goto err;
+	}
+
+  ciph = EVP_CIPHER_CTX_new();
+	if (ciph == NULL) {
+		GOSTerr(GOST_F_GOST_KEXP15, ERR_R_MALLOC_FAILURE);
+		goto err;
+	}
+
+  if (EVP_CipherInit_ex(ciph, EVP_get_cipherbynid(cipher_nid), NULL, NULL, NULL, 1) <= 0
+  || EVP_CipherInit_ex(ciph, NULL, NULL, cipher_key, iv_full, 1) <= 0
+  || EVP_CipherUpdate(ciph, out, out_len, shared_key, shared_len) <= 0
+  || EVP_CipherFinal_ex(ciph, out, out_len) <= 0) {
+		GOSTerr(GOST_F_GOST_KEXP15, ERR_R_INTERNAL_ERROR);
+		goto err;
+	}
+
+	memcpy(out + *out_len, mac_buf, mac_len);
+	*out_len += mac_len;
+
+	ret = 1;
+
+ err:
+  EVP_MD_CTX_free(mac);
+  EVP_CIPHER_CTX_free(ciph);
+
+  return ret;
+}
+
+int gost_kimp15(const char *expkey, const size_t expkeylen, 
+    int cipher_nid, const char *cipher_key, const size_t cipher_key_len,
+    int mac_nid, const char *mac_key, const size_t mac_key_len,
+    const char *iv, const size_t ivlen, 
+    char *shared_key, size_t *shared_len
+)
+{
+  return 0;
+}
+