diff --git a/src/main/java/com/github/fommil/ssh/SshRsaCrypto.java b/src/main/java/com/github/fommil/ssh/SshRsaCrypto.java
index 18c60ef..25c82cb 100644
--- a/src/main/java/com/github/fommil/ssh/SshRsaCrypto.java
+++ b/src/main/java/com/github/fommil/ssh/SshRsaCrypto.java
@@ -34,8 +34,9 @@ private BigInteger readAsnInteger(DataInputStream in) throws IOException {
         checkArgument(in.read() == 2, "no INTEGER marker");
         int length = in.read();
         if (length >= 0x80) {
-            byte[] extended = new byte[length & 0x7f];
-            in.readFully(extended);
+            byte[] extended = new byte[4];
+            int bytesToRead = length & 0x7f;
+            in.readFully(extended, 4 - bytesToRead, bytesToRead);
             length = new BigInteger(extended).intValue();
         }
         byte[] data = new byte[length];
@@ -139,4 +140,4 @@ public byte[] slurpPublicKey(String body) throws IOException {
         Base64 b64 = new Base64();
         return b64.decode(contents[1]);
     }
-}
\ No newline at end of file
+}