diff --git a/libmincrypt/Android.mk b/libmincrypt/Android.mk
index b09a941..f58eab9 100644
--- a/libmincrypt/Android.mk
+++ b/libmincrypt/Android.mk
@@ -4,13 +4,13 @@
 include $(CLEAR_VARS)
 
 LOCAL_MODULE := libmincrypt
-LOCAL_SRC_FILES := rsa.c sha.c
+LOCAL_SRC_FILES := rsa.c rsa_e_3.c rsa_e_f4.c sha.c
 include $(BUILD_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
 
 LOCAL_MODULE := libmincrypt
-LOCAL_SRC_FILES := rsa.c sha.c
+LOCAL_SRC_FILES := rsa.c rsa_e_3.c rsa_e_f4.c sha.c
 include $(BUILD_HOST_STATIC_LIBRARY)
 
 
diff --git a/libmincrypt/rsa.c b/libmincrypt/rsa.c
index d7124fb..b4ee6af 100644
--- a/libmincrypt/rsa.c
+++ b/libmincrypt/rsa.c
@@ -1,6 +1,6 @@
 /* rsa.c
 **
-** Copyright 2008, The Android Open Source Project
+** Copyright 2012, The Android Open Source Project
 **
 ** Redistribution and use in source and binary forms, with or without
 ** modification, are permitted provided that the following conditions are met:
@@ -13,186 +13,42 @@
 **       be used to endorse or promote products derived from this software
 **       without specific prior written permission.
 **
-** THIS SOFTWARE IS PROVIDED BY Google Inc. ``AS IS'' AND ANY EXPRESS OR 
+** THIS SOFTWARE IS PROVIDED BY Google Inc. ``AS IS'' AND ANY EXPRESS OR
 ** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
-** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO 
+** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 ** EVENT SHALL Google Inc. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
-** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 
-** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
-** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 
+** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 ** OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 ** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
 #include "mincrypt/rsa.h"
-#include "mincrypt/sha.h"
 
-/* a[] -= mod */
-static void subM(const RSAPublicKey *key, uint32_t *a) {
-    int64_t A = 0;
-    int i;
-    for (i = 0; i < key->len; ++i) {
-        A += (uint64_t)a[i] - key->n[i];
-        a[i] = (uint32_t)A;
-        A >>= 32;
-    }
-}
+int RSA_e_f4_verify(const RSAPublicKey* key,
+                    const uint8_t* signature,
+                    const int len,
+                    const uint8_t* sha);
 
-/* return a[] >= mod */
-static int geM(const RSAPublicKey *key, const uint32_t *a) {
-    int i;
-    for (i = key->len; i;) {
-        --i;
-        if (a[i] < key->n[i]) return 0;
-        if (a[i] > key->n[i]) return 1;
-    }
-    return 1;  /* equal */
-}
+int RSA_e_3_verify(const RSAPublicKey *key,
+                   const uint8_t *signature,
+                   const int len,
+                   const uint8_t *sha);
 
-/* montgomery c[] += a * b[] / R % mod */
-static void montMulAdd(const RSAPublicKey *key,
-                       uint32_t* c,
-                       const uint32_t a,
-                       const uint32_t* b) {
-    uint64_t A = (uint64_t)a * b[0] + c[0];
-    uint32_t d0 = (uint32_t)A * key->n0inv;
-    uint64_t B = (uint64_t)d0 * key->n[0] + (uint32_t)A;
-    int i;
-
-    for (i = 1; i < key->len; ++i) {
-        A = (A >> 32) + (uint64_t)a * b[i] + c[i];
-        B = (B >> 32) + (uint64_t)d0 * key->n[i] + (uint32_t)A;
-        c[i - 1] = (uint32_t)B;
-    }
-
-    A = (A >> 32) + (B >> 32);
-
-    c[i - 1] = (uint32_t)A;
-
-    if (A >> 32) {
-        subM(key, c);
-    }
-}
-
-/* montgomery c[] = a[] * b[] / R % mod */
-static void montMul(const RSAPublicKey *key,
-                    uint32_t* c,
-                    const uint32_t* a,
-                    const uint32_t* b) {
-    int i;
-    for (i = 0; i < key->len; ++i) {
-        c[i] = 0;
-    }
-    for (i = 0; i < key->len; ++i) {
-        montMulAdd(key, c, a[i], b);
-    }
-}
-
-/* In-place public exponentiation.
-** Input and output big-endian byte array in inout.
-*/
-static void modpow3(const RSAPublicKey *key,
-                    uint8_t* inout) {
-    uint32_t a[RSANUMWORDS];
-    uint32_t aR[RSANUMWORDS];
-    uint32_t aaR[RSANUMWORDS];
-    uint32_t *aaa = aR;  /* Re-use location. */
-    int i;
-
-    /* Convert from big endian byte array to little endian word array. */
-    for (i = 0; i < key->len; ++i) {
-        uint32_t tmp =
-            (inout[((key->len - 1 - i) * 4) + 0] << 24) |
-            (inout[((key->len - 1 - i) * 4) + 1] << 16) |
-            (inout[((key->len - 1 - i) * 4) + 2] << 8) |
-            (inout[((key->len - 1 - i) * 4) + 3] << 0);
-        a[i] = tmp;
-    }
-
-    montMul(key, aR, a, key->rr);  /* aR = a * RR / R mod M   */
-    montMul(key, aaR, aR, aR);     /* aaR = aR * aR / R mod M */
-    montMul(key, aaa, aaR, a);     /* aaa = aaR * a / R mod M */
-
-    /* Make sure aaa < mod; aaa is at most 1x mod too large. */
-    if (geM(key, aaa)) {
-        subM(key, aaa);
-    }
-
-    /* Convert to bigendian byte array */
-    for (i = key->len - 1; i >= 0; --i) {
-        uint32_t tmp = aaa[i];
-        *inout++ = tmp >> 24;
-        *inout++ = tmp >> 16;
-        *inout++ = tmp >> 8;
-        *inout++ = tmp >> 0;
-    }
-}
-
-/* Expected PKCS1.5 signature padding bytes, for a keytool RSA signature.
-** Has the 0-length optional parameter encoded in the ASN1 (as opposed to the
-** other flavor which omits the optional parameter entirely). This code does not
-** accept signatures without the optional parameter.
-*/
-static const uint8_t padding[RSANUMBYTES - SHA_DIGEST_SIZE] = {
-    0x00,0x01,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
-    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0x00,
-    0x30,0x21,0x30,0x09,0x06,0x05,0x2b,0x0e,0x03,0x02,0x1a,0x05,0x00,
-    0x04,0x14
-};
-
-/* Verify a 2048 bit RSA PKCS1.5 signature against an expected SHA-1 hash.
-** Returns 0 on failure, 1 on success.
-*/
 int RSA_verify(const RSAPublicKey *key,
                const uint8_t *signature,
                const int len,
                const uint8_t *sha) {
-    uint8_t buf[RSANUMBYTES];
-    int i;
-
-    if (key->len != RSANUMWORDS) {
-        return 0;  /* Wrong key passed in. */
-    }
-
-    if (len != sizeof(buf)) {
-        return 0;  /* Wrong input length. */
-    }
-
-    for (i = 0; i < len; ++i) {
-        buf[i] = signature[i];
-    }
-
-    modpow3(key, buf);
-
-    /* Check pkcs1.5 padding bytes. */
-    for (i = 0; i < (int) sizeof(padding); ++i) {
-        if (buf[i] != padding[i]) {
+    switch (key->exponent) {
+        case 3:
+            return RSA_e_3_verify(key, signature, len, sha);
+            break;
+        case 65537:
+            return RSA_e_f4_verify(key, signature, len, sha);
+            break;
+        default:
             return 0;
-        }
     }
-
-    /* Check sha digest matches. */
-    for (; i < len; ++i) {
-        if (buf[i] != *sha++) {
-            return 0;
-        }
-    }
-
-    return 1;
 }
diff --git a/libmincrypt/rsa_e_3.c b/libmincrypt/rsa_e_3.c
new file mode 100644
index 0000000..c8c02c4
--- /dev/null
+++ b/libmincrypt/rsa_e_3.c
@@ -0,0 +1,202 @@
+/* rsa_e_3.c
+**
+** Copyright 2008, The Android Open Source Project
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are met:
+**     * Redistributions of source code must retain the above copyright
+**       notice, this list of conditions and the following disclaimer.
+**     * Redistributions in binary form must reproduce the above copyright
+**       notice, this list of conditions and the following disclaimer in the
+**       documentation and/or other materials provided with the distribution.
+**     * Neither the name of Google Inc. nor the names of its contributors may
+**       be used to endorse or promote products derived from this software
+**       without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY Google Inc. ``AS IS'' AND ANY EXPRESS OR
+** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+** EVENT SHALL Google Inc. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+** OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include "mincrypt/rsa.h"
+#include "mincrypt/sha.h"
+
+/* a[] -= mod */
+static void subM(const RSAPublicKey *key, uint32_t *a) {
+    int64_t A = 0;
+    int i;
+    for (i = 0; i < key->len; ++i) {
+        A += (uint64_t)a[i] - key->n[i];
+        a[i] = (uint32_t)A;
+        A >>= 32;
+    }
+}
+
+/* return a[] >= mod */
+static int geM(const RSAPublicKey *key, const uint32_t *a) {
+    int i;
+    for (i = key->len; i;) {
+        --i;
+        if (a[i] < key->n[i]) return 0;
+        if (a[i] > key->n[i]) return 1;
+    }
+    return 1;  /* equal */
+}
+
+/* montgomery c[] += a * b[] / R % mod */
+static void montMulAdd(const RSAPublicKey *key,
+                       uint32_t* c,
+                       const uint32_t a,
+                       const uint32_t* b) {
+    uint64_t A = (uint64_t)a * b[0] + c[0];
+    uint32_t d0 = (uint32_t)A * key->n0inv;
+    uint64_t B = (uint64_t)d0 * key->n[0] + (uint32_t)A;
+    int i;
+
+    for (i = 1; i < key->len; ++i) {
+        A = (A >> 32) + (uint64_t)a * b[i] + c[i];
+        B = (B >> 32) + (uint64_t)d0 * key->n[i] + (uint32_t)A;
+        c[i - 1] = (uint32_t)B;
+    }
+
+    A = (A >> 32) + (B >> 32);
+
+    c[i - 1] = (uint32_t)A;
+
+    if (A >> 32) {
+        subM(key, c);
+    }
+}
+
+/* montgomery c[] = a[] * b[] / R % mod */
+static void montMul(const RSAPublicKey *key,
+                    uint32_t* c,
+                    const uint32_t* a,
+                    const uint32_t* b) {
+    int i;
+    for (i = 0; i < key->len; ++i) {
+        c[i] = 0;
+    }
+    for (i = 0; i < key->len; ++i) {
+        montMulAdd(key, c, a[i], b);
+    }
+}
+
+/* In-place public exponentiation.
+** Input and output big-endian byte array in inout.
+*/
+static void modpow3(const RSAPublicKey *key,
+                    uint8_t* inout) {
+    uint32_t a[RSANUMWORDS];
+    uint32_t aR[RSANUMWORDS];
+    uint32_t aaR[RSANUMWORDS];
+    uint32_t *aaa = aR;  /* Re-use location. */
+    int i;
+
+    /* Convert from big endian byte array to little endian word array. */
+    for (i = 0; i < key->len; ++i) {
+        uint32_t tmp =
+            (inout[((key->len - 1 - i) * 4) + 0] << 24) |
+            (inout[((key->len - 1 - i) * 4) + 1] << 16) |
+            (inout[((key->len - 1 - i) * 4) + 2] << 8) |
+            (inout[((key->len - 1 - i) * 4) + 3] << 0);
+        a[i] = tmp;
+    }
+
+    montMul(key, aR, a, key->rr);  /* aR = a * RR / R mod M   */
+    montMul(key, aaR, aR, aR);     /* aaR = aR * aR / R mod M */
+    montMul(key, aaa, aaR, a);     /* aaa = aaR * a / R mod M */
+
+    /* Make sure aaa < mod; aaa is at most 1x mod too large. */
+    if (geM(key, aaa)) {
+        subM(key, aaa);
+    }
+
+    /* Convert to bigendian byte array */
+    for (i = key->len - 1; i >= 0; --i) {
+        uint32_t tmp = aaa[i];
+        *inout++ = tmp >> 24;
+        *inout++ = tmp >> 16;
+        *inout++ = tmp >> 8;
+        *inout++ = tmp >> 0;
+    }
+}
+
+/* Expected PKCS1.5 signature padding bytes, for a keytool RSA signature.
+** Has the 0-length optional parameter encoded in the ASN1 (as opposed to the
+** other flavor which omits the optional parameter entirely). This code does not
+** accept signatures without the optional parameter.
+*/
+static const uint8_t padding[RSANUMBYTES - SHA_DIGEST_SIZE] = {
+    0x00,0x01,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
+    0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0x00,
+    0x30,0x21,0x30,0x09,0x06,0x05,0x2b,0x0e,0x03,0x02,0x1a,0x05,0x00,
+    0x04,0x14
+};
+
+/* Verify a 2048 bit RSA e=3 PKCS1.5 signature against an expected SHA-1 hash.
+** Returns 0 on failure, 1 on success.
+*/
+int RSA_e_3_verify(const RSAPublicKey *key,
+                   const uint8_t *signature,
+                   const int len,
+                   const uint8_t *sha) {
+    uint8_t buf[RSANUMBYTES];
+    int i;
+
+    if (key->len != RSANUMWORDS) {
+        return 0;  /* Wrong key passed in. */
+    }
+
+    if (len != sizeof(buf)) {
+        return 0;  /* Wrong input length. */
+    }
+
+  if (key->exponent != 3) {
+      return 0;  // Wrong exponent.
+  }
+
+    for (i = 0; i < len; ++i) {
+        buf[i] = signature[i];
+    }
+
+    modpow3(key, buf);
+
+    /* Check pkcs1.5 padding bytes. */
+    for (i = 0; i < (int) sizeof(padding); ++i) {
+        if (buf[i] != padding[i]) {
+            return 0;
+        }
+    }
+
+    /* Check sha digest matches. */
+    for (; i < len; ++i) {
+        if (buf[i] != *sha++) {
+            return 0;
+        }
+    }
+
+    return 1;
+}
diff --git a/libmincrypt/rsa_e_f4.c b/libmincrypt/rsa_e_f4.c
new file mode 100644
index 0000000..6701bcc
--- /dev/null
+++ b/libmincrypt/rsa_e_f4.c
@@ -0,0 +1,196 @@
+/* rsa_e_f4.c
+**
+** Copyright 2012, The Android Open Source Project
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are met:
+**     * Redistributions of source code must retain the above copyright
+**       notice, this list of conditions and the following disclaimer.
+**     * Redistributions in binary form must reproduce the above copyright
+**       notice, this list of conditions and the following disclaimer in the
+**       documentation and/or other materials provided with the distribution.
+**     * Neither the name of Google Inc. nor the names of its contributors may
+**       be used to endorse or promote products derived from this software
+**       without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY Google Inc. ``AS IS'' AND ANY EXPRESS OR
+** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+** EVENT SHALL Google Inc. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+** OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include "mincrypt/rsa.h"
+#include "mincrypt/sha.h"
+
+// a[] -= mod
+static void subM(const RSAPublicKey* key,
+                 uint32_t* a) {
+  int64_t A = 0;
+  int i;
+  for (i = 0; i < key->len; ++i) {
+    A += (uint64_t)a[i] - key->n[i];
+    a[i] = (uint32_t)A;
+    A >>= 32;
+  }
+}
+
+// return a[] >= mod
+static int geM(const RSAPublicKey* key,
+               const uint32_t* a) {
+  int i;
+  for (i = key->len; i;) {
+    --i;
+    if (a[i] < key->n[i]) return 0;
+    if (a[i] > key->n[i]) return 1;
+  }
+  return 1;  // equal
+}
+
+// montgomery c[] += a * b[] / R % mod
+static void montMulAdd(const RSAPublicKey* key,
+                       uint32_t* c,
+                       const uint32_t a,
+                       const uint32_t* b) {
+  uint64_t A = (uint64_t)a * b[0] + c[0];
+  uint32_t d0 = (uint32_t)A * key->n0inv;
+  uint64_t B = (uint64_t)d0 * key->n[0] + (uint32_t)A;
+  int i;
+
+  for (i = 1; i < key->len; ++i) {
+    A = (A >> 32) + (uint64_t)a * b[i] + c[i];
+    B = (B >> 32) + (uint64_t)d0 * key->n[i] + (uint32_t)A;
+    c[i - 1] = (uint32_t)B;
+  }
+
+  A = (A >> 32) + (B >> 32);
+
+  c[i - 1] = (uint32_t)A;
+
+  if (A >> 32) {
+    subM(key, c);
+  }
+}
+
+// montgomery c[] = a[] * b[] / R % mod
+static void montMul(const RSAPublicKey* key,
+                    uint32_t* c,
+                    const uint32_t* a,
+                    const uint32_t* b) {
+  int i;
+  for (i = 0; i < key->len; ++i) {
+    c[i] = 0;
+  }
+  for (i = 0; i < key->len; ++i) {
+    montMulAdd(key, c, a[i], b);
+  }
+}
+
+// In-place public exponentiation.
+// Input and output big-endian byte array in inout.
+static void modpowF4(const RSAPublicKey* key,
+                     uint8_t* inout) {
+  uint32_t a[RSANUMWORDS];
+  uint32_t aR[RSANUMWORDS];
+  uint32_t aaR[RSANUMWORDS];
+  uint32_t* aaa = aaR;  // Re-use location.
+  int i;
+
+  // Convert from big endian byte array to little endian word array.
+  for (i = 0; i < key->len; ++i) {
+    uint32_t tmp =
+      (inout[((key->len - 1 - i) * 4) + 0] << 24) |
+      (inout[((key->len - 1 - i) * 4) + 1] << 16) |
+      (inout[((key->len - 1 - i) * 4) + 2] << 8) |
+      (inout[((key->len - 1 - i) * 4) + 3] << 0);
+    a[i] = tmp;
+  }
+
+  montMul(key, aR, a, key->rr);  // aR = a * RR / R mod M
+  for (i = 0; i < 16; i += 2) {
+    montMul(key, aaR, aR, aR);  // aaR = aR * aR / R mod M
+    montMul(key, aR, aaR, aaR);  // aR = aaR * aaR / R mod M
+  }
+  montMul(key, aaa, aR, a);  // aaa = aR * a / R mod M
+
+  // Make sure aaa < mod; aaa is at most 1x mod too large.
+  if (geM(key, aaa)) {
+    subM(key, aaa);
+  }
+
+  // Convert to bigendian byte array
+  for (i = key->len - 1; i >= 0; --i) {
+    uint32_t tmp = aaa[i];
+    *inout++ = tmp >> 24;
+    *inout++ = tmp >> 16;
+    *inout++ = tmp >> 8;
+    *inout++ = tmp >> 0;
+  }
+}
+
+// Expected PKCS1.5 signature padding bytes, for a keytool RSA signature.
+// Has the 0-length optional parameter encoded in the ASN1 (as opposed to the
+// other flavor which omits the optional parameter entirely). This code does not
+// accept signatures without the optional parameter.
+/*
+static const uint8_t padding[RSANUMBYTES] = {
+0x00,0x01,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0x00,0x30,0x21,0x30,0x09,0x06,0x05,0x2b,0x0e,0x03,0x02,0x1a,0x05,0x00,0x04,0x14,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
+};
+*/
+
+// SHA-1 of PKCS1.5 signature padding for 2048 bit, as above.
+// At the location of the bytes of the hash all 00 are hashed.
+static const uint8_t kExpectedPadShaRsa2048[SHA_DIGEST_SIZE] = {
+  0xdc, 0xbd, 0xbe, 0x42, 0xd5, 0xf5, 0xa7, 0x2e, 0x6e, 0xfc,
+  0xf5, 0x5d, 0xaf, 0x9d, 0xea, 0x68, 0x7c, 0xfb, 0xf1, 0x67
+};
+
+// Verify a 2048 bit RSA e=65537 PKCS1.5 signature against an expected
+// SHA-1 hash.  Returns 0 on failure, 1 on success.
+int RSA_e_f4_verify(const RSAPublicKey* key,
+                    const uint8_t* signature,
+                    const int len,
+                    const uint8_t* sha) {
+  uint8_t buf[RSANUMBYTES];
+  int i;
+
+  if (key->len != RSANUMWORDS) {
+    return 0;  // Wrong key passed in.
+  }
+
+  if (len != sizeof(buf)) {
+    return 0;  // Wrong input length.
+  }
+
+  if (key->exponent != 65537) {
+      return 0;  // Wrong exponent.
+  }
+
+  for (i = 0; i < len; ++i) {  // Copy input to local workspace.
+    buf[i] = signature[i];
+  }
+
+  modpowF4(key, buf);  // In-place exponentiation.
+
+  // Xor sha portion, so it all becomes 00 iff equal.
+  for (i = len - SHA_DIGEST_SIZE; i < len; ++i) {
+    buf[i] ^= *sha++;
+  }
+
+  // Hash resulting buf, in-place.
+  SHA(buf, len, buf);
+
+  // Compare against expected hash value.
+  for (i = 0; i < SHA_DIGEST_SIZE; ++i) {
+    if (buf[i] != kExpectedPadShaRsa2048[i]) {
+      return 0;
+    }
+  }
+
+  return 1;  // All checked out OK.
+}
diff --git a/libmincrypt/tools/DumpPublicKey.java b/libmincrypt/tools/DumpPublicKey.java
index d2935e0..b83a757 100644
--- a/libmincrypt/tools/DumpPublicKey.java
+++ b/libmincrypt/tools/DumpPublicKey.java
@@ -34,27 +34,42 @@
 class DumpPublicKey {
     /**
      * @param key to perform sanity checks on
+     * @return version number of key.  Supported versions are:
+     *     1: 2048-bit key with e=3
+     *     2: 2048-bit key with e=65537
      * @throws Exception if the key has the wrong size or public exponent
+
      */
-    static void check(RSAPublicKey key) throws Exception {
+    static int check(RSAPublicKey key) throws Exception {
         BigInteger pubexp = key.getPublicExponent();
         BigInteger modulus = key.getModulus();
+        int version;
 
-        if (!pubexp.equals(BigInteger.valueOf(3)))
-                throw new Exception("Public exponent should be 3 but is " +
-                        pubexp.toString(10) + ".");
+        if (pubexp.equals(BigInteger.valueOf(3))) {
+            version = 1;
+        } else if (pubexp.equals(BigInteger.valueOf(65537))) {
+            version = 2;
+        } else {
+            throw new Exception("Public exponent should be 3 or 65537 but is " +
+                                pubexp.toString(10) + ".");
+        }
 
-        if (modulus.bitLength() != 2048)
+        if (modulus.bitLength() != 2048) {
              throw new Exception("Modulus should be 2048 bits long but is " +
                         modulus.bitLength() + " bits.");
+        }
+
+        return version;
     }
 
     /**
      * @param key to output
-     * @return a C initializer representing this public key.
+     * @return a String representing this public key.  If the key is a
+     *    version 1 key, the string will be a C initializer; this is
+     *    not true for newer key versions.
      */
     static String print(RSAPublicKey key) throws Exception {
-        check(key);
+        int version = check(key);
 
         BigInteger N = key.getModulus();
 
@@ -62,6 +77,12 @@
 
         int nwords = N.bitLength() / 32;    // # of 32 bit integers in modulus
 
+        if (version > 1) {
+            result.append("v");
+            result.append(Integer.toString(version));
+            result.append(" ");
+        }
+
         result.append("{");
         result.append(nwords);