1 files changed, 141 insertions, 0 deletions

diff --git a/cipher-ctr.c b/cipher-ctr.c
new file mode 100644
index 000000000..a2bab5c14
--- /dev/null
+++ b/cipher-ctr.c
@@ -0,0 +1,141 @@
+/*
+ * Copyright (c) 2003 Markus Friedl <markus@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+#include "includes.h"
+RCSID("$OpenBSD: cipher-ctr.c,v 1.2 2003/06/17 18:14:23 markus Exp $");
+
+#include <openssl/evp.h>
+
+#include "log.h"
+#include "xmalloc.h"
+
+#if OPENSSL_VERSION_NUMBER < 0x00907000L
+#include "rijndael.h"
+#define AES_KEY rijndael_ctx
+#define AES_BLOCK_SIZE 16
+#define AES_encrypt(a, b, c) rijndael_encrypt(c, a, b)
+#define AES_set_encrypt_key(a, b, c) rijndael_set_key(c, (char *)a, b, 1)
+#else
+#include <openssl/aes.h>
+#endif
+
+const EVP_CIPHER *evp_aes_128_ctr(void);
+void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
+
+struct ssh_aes_ctr_ctx
+{
+        AES_KEY         aes_ctx;
+        u_char          aes_counter[AES_BLOCK_SIZE];
+};
+
+/*
+ * increment counter 'ctr',
+ * the counter is of size 'len' bytes and stored in network-byte-order.
+ * (LSB at ctr[len-1], MSB at ctr[0])
+ */
+static void
+ssh_ctr_inc(u_char *ctr, u_int len)
+{
+        int i;
+
+        for (i = len - 1; i >= 0; i--)
+                if (++ctr[i])   /* continue on overflow */
+                        return;
+}
+
+static int
+ssh_aes_ctr(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
+    u_int len)
+{
+        struct ssh_aes_ctr_ctx *c;
+        u_int n = 0;
+        u_char buf[AES_BLOCK_SIZE];
+
+        if (len == 0)
+                return (1);
+        if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL)
+                return (0);
+
+        while ((len--) > 0) {
+                if (n == 0) {
+                        AES_encrypt(c->aes_counter, buf, &c->aes_ctx);
+                        ssh_ctr_inc(c->aes_counter, AES_BLOCK_SIZE);
+                }
+                *(dest++) = *(src++) ^ buf[n];
+                n = (n + 1) % AES_BLOCK_SIZE;
+        }
+        return (1);
+}
+
+static int
+ssh_aes_ctr_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
+    int enc)
+{
+        struct ssh_aes_ctr_ctx *c;
+
+        if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
+                c = xmalloc(sizeof(*c));
+                EVP_CIPHER_CTX_set_app_data(ctx, c);
+        }
+        if (key != NULL)
+                AES_set_encrypt_key(key, ctx->key_len * 8, &c->aes_ctx);
+        if (iv != NULL)
+                memcpy(c->aes_counter, iv, AES_BLOCK_SIZE);
+        return (1);
+}
+
+static int
+ssh_aes_ctr_cleanup(EVP_CIPHER_CTX *ctx)
+{
+        struct ssh_aes_ctr_ctx *c;
+
+        if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
+                memset(c, 0, sizeof(*c));
+                xfree(c);
+                EVP_CIPHER_CTX_set_app_data(ctx, NULL);
+        }
+        return (1);
+}
+
+void
+ssh_aes_ctr_iv(EVP_CIPHER_CTX *evp, int doset, u_char * iv, u_int len)
+{
+        struct ssh_aes_ctr_ctx *c;
+
+        if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
+                fatal("ssh_aes_ctr_iv: no context");
+        if (doset)
+                memcpy(c->aes_counter, iv, len);
+        else
+                memcpy(iv, c->aes_counter, len);
+}
+
+const EVP_CIPHER *
+evp_aes_128_ctr(void)
+{
+        static EVP_CIPHER aes_ctr;
+
+        memset(&aes_ctr, 0, sizeof(EVP_CIPHER));
+        aes_ctr.nid = NID_undef;
+        aes_ctr.block_size = AES_BLOCK_SIZE;
+        aes_ctr.iv_len = AES_BLOCK_SIZE;
+        aes_ctr.key_len = 16;
+        aes_ctr.init = ssh_aes_ctr_init;
+        aes_ctr.cleanup = ssh_aes_ctr_cleanup;
+        aes_ctr.do_cipher = ssh_aes_ctr;
+        aes_ctr.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
+            EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CUSTOM_IV;
+        return (&aes_ctr);
+}