diff --git a/rsa-decrypt-tr.c b/rsa-decrypt-tr.c
index 4705137..33ea3d5 100644
--- a/rsa-decrypt-tr.c
+++ b/rsa-decrypt-tr.c
@@ -47,7 +47,7 @@ rsa_decrypt_tr(const struct rsa_public_key *pub,
   mpz_init (ri);
 
   _rsa_blind (pub, random_ctx, random, m, ri);
-  rsa_compute_root(key, m, m);
+  rsa_compute_root_ar(pub, key, m, m);
   _rsa_unblind (pub, m, ri);
   mpz_clear (ri);
 
diff --git a/rsa-pkcs1-sign-tr.c b/rsa-pkcs1-sign-tr.c
index 16de2f9..31417c5 100644
--- a/rsa-pkcs1-sign-tr.c
+++ b/rsa-pkcs1-sign-tr.c
@@ -45,7 +45,7 @@ rsa_pkcs1_sign_tr(const struct rsa_public_key *pub,
       mpz_init (ri);
 
       _rsa_blind (pub, random_ctx, random, s, ri);
-      rsa_compute_root(key, s, s);
+      rsa_compute_root_ar(pub, key, s, s);
       _rsa_unblind (pub, s, ri);
 
       mpz_clear (ri);
diff --git a/rsa-sign.c b/rsa-sign.c
index 56adda3..cc80faa 100644
--- a/rsa-sign.c
+++ b/rsa-sign.c
@@ -78,13 +78,20 @@ rsa_private_key_prepare(struct rsa_private_key *key)
 
 /* Computing an rsa root. */
 void
-rsa_compute_root(const struct rsa_private_key *key,
-		 mpz_t x, const mpz_t m)
+rsa_compute_root_ar(const struct rsa_public_key *pub,
+		    const struct rsa_private_key *key,
+		    mpz_t x, const mpz_t _m)
 {
   mpz_t xp; /* modulo p */
   mpz_t xq; /* modulo q */
+  mpz_t m; /* m=_m mod n */
+
+  mpz_init(xp); mpz_init(xq); mpz_init(m);
 
-  mpz_init(xp); mpz_init(xq);    
+  if (pub != NULL)
+    mpz_fdiv_r(m, _m, pub->n);
+  else
+    mpz_set(m, _m);
 
   /* Compute xq = m^d % q = (m%q)^b % q */
   mpz_fdiv_r(xq, m, key->q);
@@ -132,5 +139,12 @@ rsa_compute_root(const struct rsa_private_key *key,
   mpz_mul(x, key->q, xp);
   mpz_add(x, x, xq);
 
-  mpz_clear(xp); mpz_clear(xq);
+  mpz_clear(xp); mpz_clear(xq); mpz_clear(m);
+}
+
+void
+rsa_compute_root(const struct rsa_private_key *key,
+		 mpz_t x, const mpz_t m)
+{
+	return rsa_compute_root_ar(NULL, key, x, m);
 }
diff --git a/rsa.h b/rsa.h
index 38455a7..34c0992 100644
--- a/rsa.h
+++ b/rsa.h
@@ -67,6 +67,7 @@ extern "C" {
 #define rsa_decrypt nettle_rsa_decrypt
 #define rsa_decrypt_tr nettle_rsa_decrypt_tr
 #define rsa_compute_root nettle_rsa_compute_root
+#define rsa_compute_root_ar nettle_rsa_compute_root_ar
 #define rsa_generate_keypair nettle_rsa_generate_keypair
 #define rsa_keypair_to_sexp nettle_rsa_keypair_to_sexp
 #define rsa_keypair_from_sexp_alist nettle_rsa_keypair_from_sexp_alist
@@ -307,6 +308,12 @@ void
 rsa_compute_root(const struct rsa_private_key *key,
 		 mpz_t x, const mpz_t m);
 
+/* The acoustic resistant version: http://www.cs.tau.ac.il/~tromer/acoustic/ */
+void
+rsa_compute_root_ar(const struct rsa_public_key *pub,
+		    const struct rsa_private_key *key,
+		    mpz_t x, const mpz_t m);
+
 
 /* Key generation */