code review 5625045: crypto/...: more fixes for bug 2841

src/pkg/crypto/rand/rand_unix.go

 // Copyright 2010 The Go Authors.  All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // +build darwin freebsd linux netbsd openbsd
 
 // Unix cryptographically secure pseudorandom number
 // generator.
 
 package rand
 
 import (
         "bufio"
         "crypto/aes"
+        "crypto/cipher"
         "io"
         "os"
         "sync"
         "time"
 )
 
 // Easy implementation: read from /dev/urandom.
 // This is sufficient on Linux, OS X, and FreeBSD.
 
 func init() { Reader = &devReader{name: "/dev/urandom"} }
@@ skipping 34 matching lines @@
 func newReader(entropy io.Reader) io.Reader {
         if entropy == nil {
                 entropy = &devReader{name: "/dev/random"}
         }
         return &reader{entropy: entropy}
 }
 
 type reader struct {
         mu                   sync.Mutex
         budget               int // number of bytes that can be generated
-        cipher               *aes.Cipher
+        cipher               cipher.Block
         entropy              io.Reader
         time, seed, dst, key [aes.BlockSize]byte
 }
 
 func (r *reader) Read(b []byte) (n int, err error) {
         r.mu.Lock()
         defer r.mu.Unlock()
         n = len(b)
 
         for len(b) > 0 {
@@ skipping 38 matching lines @@
                         r.seed[i] = r.time[i] ^ r.dst[i]
                 }
                 r.cipher.Encrypt(r.seed[0:], r.seed[0:])
 
                 m := copy(b, r.dst[0:])
                 b = b[m:]
         }
 
         return n, nil
 }