1 files changed, 43 insertions, 0 deletions
diff --git a/src/pkg/crypto/rand/rand_windows.go b/src/pkg/crypto/rand/rand_windows.go
new file mode 100755
index 000000000..4b2b7a26f
--- /dev/null
+++ b/src/pkg/crypto/rand/rand_windows.go
@@ -0,0 +1,43 @@
+// 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 {
+			r.mu.Unlock()
+			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
+}