1 files changed, 134 insertions, 0 deletions
diff --git a/third_party/bearssl/src/ecdsa_atr.c b/third_party/bearssl/src/ecdsa_atr.c
new file mode 100644
index 0000000..3a11226
--- /dev/null
+++ b/third_party/bearssl/src/ecdsa_atr.c
@@ -0,0 +1,134 @@
+/*
+ * 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"
+
+/* see bearssl_ec.h */
+size_t
+br_ecdsa_asn1_to_raw(void *sig, size_t sig_len)
+{
+	/*
+	 * Note: this code is a bit lenient in that it accepts a few
+	 * deviations to DER with regards to minimality of encoding of
+	 * lengths and integer values. These deviations are still
+	 * unambiguous.
+	 *
+	 * Signature format is a SEQUENCE of two INTEGER values. We
+	 * support only integers of less than 127 bytes each (signed
+	 * encoding) so the resulting raw signature will have length
+	 * at most 254 bytes.
+	 */
+
+	unsigned char *buf, *r, *s;
+	size_t zlen, rlen, slen, off;
+	unsigned char tmp[254];
+
+	buf = sig;
+	if (sig_len < 8) {
+		return 0;
+	}
+
+	/*
+	 * First byte is SEQUENCE tag.
+	 */
+	if (buf[0] != 0x30) {
+		return 0;
+	}
+
+	/*
+	 * The SEQUENCE length will be encoded over one or two bytes. We
+	 * limit the total SEQUENCE contents to 255 bytes, because it
+	 * makes things simpler; this is enough for subgroup orders up
+	 * to 999 bits.
+	 */
+	zlen = buf[1];
+	if (zlen > 0x80) {
+		if (zlen != 0x81) {
+			return 0;
+		}
+		zlen = buf[2];
+		if (zlen != sig_len - 3) {
+			return 0;
+		}
+		off = 3;
+	} else {
+		if (zlen != sig_len - 2) {
+			return 0;
+		}
+		off = 2;
+	}
+
+	/*
+	 * First INTEGER (r).
+	 */
+	if (buf[off ++] != 0x02) {
+		return 0;
+	}
+	rlen = buf[off ++];
+	if (rlen >= 0x80) {
+		return 0;
+	}
+	r = buf + off;
+	off += rlen;
+
+	/*
+	 * Second INTEGER (s).
+	 */
+	if (off + 2 > sig_len) {
+		return 0;
+	}
+	if (buf[off ++] != 0x02) {
+		return 0;
+	}
+	slen = buf[off ++];
+	if (slen >= 0x80 || slen != sig_len - off) {
+		return 0;
+	}
+	s = buf + off;
+
+	/*
+	 * Removing leading zeros from r and s.
+	 */
+	while (rlen > 0 && *r == 0) {
+		rlen --;
+		r ++;
+	}
+	while (slen > 0 && *s == 0) {
+		slen --;
+		s ++;
+	}
+
+	/*
+	 * Compute common length for the two integers, then copy integers
+	 * into the temporary buffer, and finally copy it back over the
+	 * signature buffer.
+	 */
+	zlen = rlen > slen ? rlen : slen;
+	sig_len = zlen << 1;
+	memset(tmp, 0, sig_len);
+	memcpy(tmp + zlen - rlen, r, rlen);
+	memcpy(tmp + sig_len - slen, s, slen);
+	memcpy(sig, tmp, sig_len);
+	return sig_len;
+}