1 files changed, 63 insertions, 0 deletions
diff --git a/src/sk-ecdsa.c b/src/sk-ecdsa.c
new file mode 100644
index 0000000..bed7e50
--- /dev/null
+++ b/src/sk-ecdsa.c
@@ -0,0 +1,63 @@
+#include "includes.h"
+
+#if DROPBEAR_SK_ECDSA
+
+#include "dbutil.h"
+#include "ecc.h"
+#include "ecdsa.h"
+#include "sk-ecdsa.h"
+#include "ssh.h"
+
+int buf_sk_ecdsa_verify(buffer *buf, const ecc_key *key, const buffer *data_buf,
+			const char* app, unsigned int applen,
+			unsigned char sk_flags_mask) {
+	hash_state hs;
+	unsigned char subhash[SHA256_HASH_SIZE];
+	buffer *sk_buffer = NULL, *sig_buffer = NULL;
+	unsigned char flags;
+	unsigned int counter;
+	int ret;
+
+	TRACE(("buf_sk_ecdsa_verify"))
+
+	/* from https://github.com/openssh/openssh-portable/blob/master/PROTOCOL.u2f */
+	/* ecdsa signature to verify (r, s) */
+	sig_buffer = buf_getbuf(buf);
+
+	flags = buf_getbyte (buf);
+	counter = buf_getint (buf);
+	/* create the message to be signed */
+	sk_buffer = buf_new (2*SHA256_HASH_SIZE+5);
+	sha256_init (&hs);
+	sha256_process (&hs, app, applen);
+	sha256_done (&hs, subhash);
+	buf_putbytes (sk_buffer, subhash, sizeof (subhash));
+	buf_putbyte (sk_buffer, flags);
+	buf_putint (sk_buffer, counter);
+	sha256_init (&hs);
+	sha256_process (&hs, data_buf->data, data_buf->len);
+	sha256_done (&hs, subhash);
+	buf_putbytes (sk_buffer, subhash, sizeof (subhash));
+
+	ret = buf_ecdsa_verify(sig_buffer, key, sk_buffer);
+	buf_free(sk_buffer);
+	buf_free(sig_buffer);
+
+	if (~flags & sk_flags_mask & SSH_SK_USER_PRESENCE_REQD) {
+		if (ret == DROPBEAR_SUCCESS) {
+			dropbear_log(LOG_WARNING, "Rejecting, user-presence not set");
+		}
+		ret = DROPBEAR_FAILURE;
+	}
+	if (~flags & sk_flags_mask & SSH_SK_USER_VERIFICATION_REQD) {
+		if (ret == DROPBEAR_SUCCESS) {
+			dropbear_log(LOG_WARNING, "Rejecting, user-verification not set");
+		}
+		ret = DROPBEAR_FAILURE;
+	}
+
+	TRACE(("leave buf_sk_ecdsa_verify, ret=%d", ret))
+	return ret;
+}
+
+#endif /* DROPBEAR_SK_ECDSA */