crypto/rand for Windows
R=rsc, brainman
CC=golang-dev
https://golang.org/cl/1773041
diff --git a/src/pkg/crypto/rand/rand_windows.go b/src/pkg/crypto/rand/rand_windows.go
new file mode 100755
index 0000000..9bab2cb
--- /dev/null
+++ b/src/pkg/crypto/rand/rand_windows.go
@@ -0,0 +1,42 @@
+// 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.
+
+// Windows cryptographically secure pseudorandom number
+// generator.
+
+package rand
+
+import (
+ "os"
+ "sync"
+ "syscall"
+)
+
+// Implemented by using Windows CryptoAPI 2.0.
+
+func init() { Reader = &rngReader{} }
+
+// A rngReader satisfies reads by reading from the Windows CryptGenRandom API.
+type rngReader struct {
+ prov uint32
+ mu sync.Mutex
+}
+
+func (r *rngReader) Read(b []byte) (n int, err os.Error) {
+ r.mu.Lock()
+ if r.prov == 0 {
+ const provType = syscall.PROV_RSA_FULL
+ const flags = syscall.CRYPT_VERIFYCONTEXT | syscall.CRYPT_SILENT
+ ok, errno := syscall.CryptAcquireContext(&r.prov, nil, nil, provType, flags)
+ if !ok {
+ return 0, os.NewSyscallError("CryptAcquireContext", errno)
+ }
+ }
+ r.mu.Unlock()
+ ok, errno := syscall.CryptGenRandom(r.prov, uint32(len(b)), &b[0])
+ if !ok {
+ return 0, os.NewSyscallError("CryptGenRandom", errno)
+ }
+ return len(b), nil
+}
