--- a/rsa.c	Tue May 26 23:27:26 2020 +0800
+++ b/rsa.c	Tue May 26 17:36:47 2020 +0200
@@ -211,12 +211,12 @@
 	m_mp_init_multi(&rsa_mdash, &rsa_s, &rsa_em, NULL);
 
 	slen = buf_getint(buf);
-	if (slen != (unsigned int)mp_unsigned_bin_size(key->n)) {
+	if (slen != (unsigned int)mp_ubin_size(key->n)) {
 		TRACE(("bad size"))
 		goto out;
 	}
 
-	if (mp_read_unsigned_bin(&rsa_s, buf_getptr(buf, buf->len - buf->pos),
+	if (mp_from_ubin(&rsa_s, buf_getptr(buf, buf->len - buf->pos),
 				buf->len - buf->pos) != MP_OKAY) {
 		TRACE(("failed reading rsa_s"))
 		goto out;
@@ -257,6 +257,7 @@
 	const char *name = NULL;
 	unsigned int nsize, ssize, namelen = 0;
 	unsigned int i;
+	size_t written;
 	DEF_MP_INT(rsa_s);
 	DEF_MP_INT(rsa_tmp1);
 	DEF_MP_INT(rsa_tmp2);
@@ -322,21 +323,21 @@
 	name = signature_name_from_type(sigtype, &namelen);
 	buf_putstring(buf, name, namelen);
 
-	nsize = mp_unsigned_bin_size(key->n);
+	nsize = mp_ubin_size(key->n);
 
 	/* string rsa_signature_blob length */
 	buf_putint(buf, nsize);
 	/* pad out s to same length as n */
-	ssize = mp_unsigned_bin_size(&rsa_s);
+	ssize = mp_ubin_size(&rsa_s);
 	dropbear_assert(ssize <= nsize);
 	for (i = 0; i < nsize-ssize; i++) {
 		buf_putbyte(buf, 0x00);
 	}
 
-	if (mp_to_unsigned_bin(&rsa_s, buf_getwriteptr(buf, ssize)) != MP_OKAY) {
+	if (mp_to_ubin(&rsa_s, buf_getwriteptr(buf, ssize), ssize, &written) != MP_OKAY) {
 		dropbear_exit("RSA error");
 	}
-	buf_incrwritepos(buf, ssize);
+	buf_incrwritepos(buf, written);
 	mp_clear(&rsa_s);
 
 #if defined(DEBUG_RSA) && DEBUG_TRACE
@@ -397,7 +398,8 @@
 			assert(0);
 	}
 	
-	nsize = mp_unsigned_bin_size(key->n);
+
+	nsize = mp_ubin_size(key->n);
 
 	rsa_EM = buf_new(nsize);
 	/* type byte */