diff --git a/src/libextra/crypto/cryptoutil.rs b/src/libextra/crypto/cryptoutil.rs
index 6e791f90b233..33ab6a9bcb96 100644
--- a/src/libextra/crypto/cryptoutil.rs
+++ b/src/libextra/crypto/cryptoutil.rs
@@ -241,3 +241,36 @@ impl <T: FixedBuffer> StandardPadding for T {
         self.zero_until(size - rem);
     }
 }
+
+
+#[cfg(test)]
+mod test {
+    use std::rand::IsaacRng;
+    use std::rand::RngUtil;
+    use std::vec;
+
+    use digest::Digest;
+
+    /// Feed 1,000,000 'a's into the digest with varying input sizes and check that the result is
+    /// correct.
+    pub fn test_digest_1million_random<D: Digest>(digest: &mut D, blocksize: uint, expected: &str) {
+        let total_size = 1000000;
+        let buffer = vec::from_elem(blocksize * 2, 'a' as u8);
+        let mut rng = IsaacRng::new_unseeded();
+        let mut count = 0;
+
+        digest.reset();
+
+        while count < total_size {
+            let next: uint = rng.gen_uint_range(0, 2 * blocksize + 1);
+            let remaining = total_size - count;
+            let size = if next > remaining { remaining } else { next };
+            digest.input(buffer.slice_to(size));
+            count += size;
+        }
+
+        let result_str = digest.result_str();
+
+        assert!(expected == result_str);
+    }
+}
diff --git a/src/libextra/crypto/sha1.rs b/src/libextra/crypto/sha1.rs
index cf9604a3c91b..0172f6af18e8 100644
--- a/src/libextra/crypto/sha1.rs
+++ b/src/libextra/crypto/sha1.rs
@@ -240,7 +240,7 @@ impl Digest for Sha1 {
 
 #[cfg(test)]
 mod tests {
-
+    use cryptoutil::test::test_digest_1million_random;
     use digest::Digest;
     use sha1::Sha1;
 
@@ -253,15 +253,6 @@ mod tests {
 
     #[test]
     fn test() {
-        fn a_million_letter_a() -> ~str {
-            let mut i = 0;
-            let mut rs = ~"";
-            while i < 100000 {
-                rs.push_str("aaaaaaaaaa");
-                i += 1;
-            }
-            return rs;
-        }
         // Test messages from FIPS 180-1
 
         let fips_180_1_tests = ~[
@@ -289,17 +280,6 @@ mod tests {
                 ],
                 output_str: ~"84983e441c3bd26ebaae4aa1f95129e5e54670f1"
             },
-            Test {
-                input: a_million_letter_a(),
-                output: ~[
-                    0x34u8, 0xAAu8, 0x97u8, 0x3Cu8,
-                    0xD4u8, 0xC4u8, 0xDAu8, 0xA4u8,
-                    0xF6u8, 0x1Eu8, 0xEBu8, 0x2Bu8,
-                    0xDBu8, 0xADu8, 0x27u8, 0x31u8,
-                    0x65u8, 0x34u8, 0x01u8, 0x6Fu8,
-                ],
-                output_str: ~"34aa973cd4c4daa4f61eeb2bdbad27316534016f"
-            },
         ];
         // Examples from wikipedia
 
@@ -366,6 +346,15 @@ mod tests {
             sh.reset();
         }
     }
+
+    #[test]
+    fn test_1million_random_sha1() {
+        let mut sh = Sha1::new();
+        test_digest_1million_random(
+            &mut sh,
+            64,
+            "34aa973cd4c4daa4f61eeb2bdbad27316534016f");
+    }
 }
 
 #[cfg(test)]
diff --git a/src/libextra/crypto/sha2.rs b/src/libextra/crypto/sha2.rs
index 46a135a79e7f..b91a54efc928 100644
--- a/src/libextra/crypto/sha2.rs
+++ b/src/libextra/crypto/sha2.rs
@@ -756,6 +756,7 @@ static H224: [u32, ..8] = [
 
 #[cfg(test)]
 mod tests {
+    use cryptoutil::test::test_digest_1million_random;
     use digest::Digest;
     use sha2::{Sha512, Sha384, Sha512Trunc256, Sha512Trunc224, Sha256, Sha224};
 
@@ -947,6 +948,25 @@ mod tests {
 
         test_hash(sh, tests);
     }
+
+    #[test]
+    fn test_1million_random_sha512() {
+        let mut sh = Sha512::new();
+        test_digest_1million_random(
+            &mut sh,
+            128,
+            "e718483d0ce769644e2e42c7bc15b4638e1f98b13b2044285632a803afa973eb" +
+            "de0ff244877ea60a4cb0432ce577c31beb009c5c2c49aa2e4eadb217ad8cc09b");
+        }
+
+    #[test]
+    fn test_1million_random_sha256() {
+        let mut sh = Sha256::new();
+        test_digest_1million_random(
+            &mut sh,
+            64,
+            "cdc76e5c9914fb9281a1c7e284d73e67f1809a48a497200e046d39ccc7112cd0");
+    }
 }