1 files changed, 121 insertions, 0 deletions
diff --git a/third_party/bearssl/src/ecdsa_rta.c b/third_party/bearssl/src/ecdsa_rta.c
new file mode 100644
index 0000000..005c62c
--- /dev/null
+++ b/third_party/bearssl/src/ecdsa_rta.c
@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2016 Thomas Pornin <[email protected]>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining 
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be 
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "inner.h"
+
+/*
+ * Compute ASN.1 encoded length for the provided integer. The ASN.1
+ * encoding is signed, so its leading bit must have value 0; it must
+ * also be of minimal length (so leading bytes of value 0 must be
+ * removed, except if that would contradict the rule about the sign
+ * bit).
+ */
+static size_t
+asn1_int_length(const unsigned char *x, size_t xlen)
+{
+	while (xlen > 0 && *x == 0) {
+		x ++;
+		xlen --;
+	}
+	if (xlen == 0 || *x >= 0x80) {
+		xlen ++;
+	}
+	return xlen;
+}
+
+/* see bearssl_ec.h */
+size_t
+br_ecdsa_raw_to_asn1(void *sig, size_t sig_len)
+{
+	/*
+	 * Internal buffer is large enough to accommodate a signature
+	 * such that r and s fit on 125 bytes each (signed encoding),
+	 * meaning a curve order of up to 999 bits. This is the limit
+	 * that ensures "simple" length encodings.
+	 */
+	unsigned char *buf;
+	size_t hlen, rlen, slen, zlen, off;
+	unsigned char tmp[257];
+
+	buf = sig;
+	if ((sig_len & 1) != 0) {
+		return 0;
+	}
+
+	/*
+	 * Compute lengths for the two integers.
+	 */
+	hlen = sig_len >> 1;
+	rlen = asn1_int_length(buf, hlen);
+	slen = asn1_int_length(buf + hlen, hlen);
+	if (rlen > 125 || slen > 125) {
+		return 0;
+	}
+
+	/*
+	 * SEQUENCE header.
+	 */
+	tmp[0] = 0x30;
+	zlen = rlen + slen + 4;
+	if (zlen >= 0x80) {
+		tmp[1] = 0x81;
+		tmp[2] = zlen;
+		off = 3;
+	} else {
+		tmp[1] = zlen;
+		off = 2;
+	}
+
+	/*
+	 * First INTEGER (r).
+	 */
+	tmp[off ++] = 0x02;
+	tmp[off ++] = rlen;
+	if (rlen > hlen) {
+		tmp[off] = 0x00;
+		memcpy(tmp + off + 1, buf, hlen);
+	} else {
+		memcpy(tmp + off, buf + hlen - rlen, rlen);
+	}
+	off += rlen;
+
+	/*
+	 * Second INTEGER (s).
+	 */
+	tmp[off ++] = 0x02;
+	tmp[off ++] = slen;
+	if (slen > hlen) {
+		tmp[off] = 0x00;
+		memcpy(tmp + off + 1, buf + hlen, hlen);
+	} else {
+		memcpy(tmp + off, buf + sig_len - slen, slen);
+	}
+	off += slen;
+
+	/*
+	 * Return ASN.1 signature.
+	 */
+	memcpy(sig, tmp, off);
+	return off;
+}