1 files changed, 146 insertions, 0 deletions

diff --git a/bufec.c b/bufec.c
new file mode 100644
index 000000000..3dcb49477
--- /dev/null
+++ b/bufec.c
@@ -0,0 +1,146 @@
+/* $OpenBSD: bufec.c,v 1.1 2010/08/31 11:54:45 djm Exp $ */
+/*
+ * Copyright (c) 2010 Damien Miller <djm@mindrot.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"
+
+#ifdef OPENSSL_HAS_ECC
+
+#include <sys/types.h>
+
+#include <openssl/bn.h>
+#include <openssl/ec.h>
+
+#include <string.h>
+#include <stdarg.h>
+
+#include "xmalloc.h"
+#include "buffer.h"
+#include "log.h"
+#include "misc.h"
+
+/*
+ * Maximum supported EC GFp field length is 528 bits. SEC1 uncompressed
+ * encoding represents this as two bitstring points that should each
+ * be no longer than the field length, SEC1 specifies a 1 byte
+ * point type header.
+ * Being paranoid here may insulate us to parsing problems in
+ * EC_POINT_oct2point.
+ */
+#define BUFFER_MAX_ECPOINT_LEN ((528*2 / 8) + 1)
+
+/*
+ * Append an EC_POINT to the buffer as a string containing a SEC1 encoded
+ * uncompressed point. Fortunately OpenSSL handles the gory details for us.
+ */
+int
+buffer_put_ecpoint_ret(Buffer *buffer, const EC_GROUP *curve,
+    const EC_POINT *point)
+{
+        u_char *buf = NULL;
+        size_t len;
+        BN_CTX *bnctx;
+        int ret = -1;
+
+        /* Determine length */
+        if ((bnctx = BN_CTX_new()) == NULL)
+                fatal("%s: BN_CTX_new failed", __func__);
+        len = EC_POINT_point2oct(curve, point, POINT_CONVERSION_UNCOMPRESSED,
+            NULL, 0, bnctx);
+        if (len > BUFFER_MAX_ECPOINT_LEN) {
+                error("%s: giant EC point: len = %lu (max %u)",
+                    __func__, (u_long)len, BUFFER_MAX_ECPOINT_LEN);
+                goto out;
+        }
+        /* Convert */
+        buf = xmalloc(len);
+        if (EC_POINT_point2oct(curve, point, POINT_CONVERSION_UNCOMPRESSED,
+            buf, len, bnctx) != len) {
+                error("%s: EC_POINT_point2oct length mismatch", __func__);
+                goto out;
+        }
+        /* Append */
+        buffer_put_string(buffer, buf, len);
+        ret = 0;
+ out:
+        if (buf != NULL) {
+                bzero(buf, len);
+                xfree(buf);
+        }
+        BN_CTX_free(bnctx);
+        return ret;
+}
+
+void
+buffer_put_ecpoint(Buffer *buffer, const EC_GROUP *curve,
+    const EC_POINT *point)
+{
+        if (buffer_put_ecpoint_ret(buffer, curve, point) == -1)
+                fatal("%s: buffer error", __func__);
+}
+
+int
+buffer_get_ecpoint_ret(Buffer *buffer, const EC_GROUP *curve,
+    EC_POINT *point)
+{
+        u_char *buf;
+        u_int len;
+        BN_CTX *bnctx;
+        int ret = -1;
+
+        if ((buf = buffer_get_string_ret(buffer, &len)) == NULL) {
+                error("%s: invalid point", __func__);
+                return -1;
+        }
+        if ((bnctx = BN_CTX_new()) == NULL)
+                fatal("%s: BN_CTX_new failed", __func__);
+        if (len > BUFFER_MAX_ECPOINT_LEN) {
+                error("%s: EC_POINT too long: %u > max %u", __func__,
+                    len, BUFFER_MAX_ECPOINT_LEN);
+                goto out;
+        }
+        if (len == 0) {
+                error("%s: EC_POINT buffer is empty", __func__);
+                goto out;
+        }
+        if (buf[0] != POINT_CONVERSION_UNCOMPRESSED) {
+                error("%s: EC_POINT is in an incorrect form: "
+                    "0x%02x (want 0x%02x)", __func__, buf[0],
+                    POINT_CONVERSION_UNCOMPRESSED);
+                goto out;
+        }
+        if (EC_POINT_oct2point(curve, point, buf, len, bnctx) != 1) {
+                error("buffer_get_bignum2_ret: BN_bin2bn failed");
+                goto out;
+        }
+        /* EC_POINT_oct2point verifies that the point is on the curve for us */
+        ret = 0;
+ out:
+        BN_CTX_free(bnctx);
+        bzero(buf, len);
+        xfree(buf);
+        return ret;
+}
+
+void
+buffer_get_ecpoint(Buffer *buffer, const EC_GROUP *curve,
+    EC_POINT *point)
+{
+        if (buffer_get_ecpoint_ret(buffer, curve, point) == -1)
+                fatal("%s: buffer error", __func__);
+}
+
+#endif /* OPENSSL_HAS_ECC */