From 5a0d3acd041f229e0b9d48c35682af4b94b9affb Mon Sep 17 00:00:00 2001
From: Jesse Luehrs <doy@tozt.net>
Date: Wed, 13 May 2015 15:28:09 -0400
Subject: also allow padding sha1 with a user-specified length

---
 src/lib.rs  |  1 +
 src/sha1.rs | 16 +++++++++++-----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 112f968..2252129 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -29,6 +29,7 @@ pub use random::MersenneTwister;
 pub use random::mt19937_stream_cipher;
 pub use sha1::sha1;
 pub use sha1::pad_sha1;
+pub use sha1::sha1_padding;
 pub use sha1::sha1_with_state;
 pub use sha1::sha1_mac;
 pub use crack::BlockCipherMode;
diff --git a/src/sha1.rs b/src/sha1.rs
index bb6d82c..bcd9295 100644
--- a/src/sha1.rs
+++ b/src/sha1.rs
@@ -14,16 +14,22 @@ pub fn sha1 (bytes: &[u8]) -> [u8; 20] {
 }
 
 pub fn pad_sha1 (bytes: &[u8]) -> Vec<u8> {
-    let ml: u64 = bytes.len() as u64 * 8;
+    return bytes
+        .iter()
+        .map(|x| *x)
+        .chain(sha1_padding(bytes.len() as u64))
+        .collect();
+}
+
+pub fn sha1_padding (len: u64) -> Vec<u8> {
+    let ml: u64 = len * 8;
     let ml_bytes: [u8; 8] = unsafe {
         ::std::mem::transmute(ml.to_be())
     };
-
-    return bytes
+    return [0x80u8]
         .iter()
         .map(|x| *x)
-        .chain(::std::iter::repeat(0x80).take(1))
-        .chain(::std::iter::repeat(0x00).take(55 - (bytes.len() % 64)))
+        .chain(::std::iter::repeat(0x00).take(55 - (len % 64) as usize))
         .chain(ml_bytes.iter().map(|x| *x))
         .collect();
 }
-- 
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