Imported Upstream version 1.4upstream/1.4

1 files changed, 47 insertions, 0 deletions

diff --git a/src/crypto/rand/rand_windows.go b/src/crypto/rand/rand_windows.go
new file mode 100644
index 000000000..82b39b64a
--- /dev/null
+++ b/src/crypto/rand/rand_windows.go
@@ -0,0 +1,47 @@
+// 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 syscall.Handle
+	mu   sync.Mutex
+}
+
+func (r *rngReader) Read(b []byte) (n int, err error) {
+	r.mu.Lock()
+	if r.prov == 0 {
+		const provType = syscall.PROV_RSA_FULL
+		const flags = syscall.CRYPT_VERIFYCONTEXT | syscall.CRYPT_SILENT
+		err := syscall.CryptAcquireContext(&r.prov, nil, nil, provType, flags)
+		if err != nil {
+			r.mu.Unlock()
+			return 0, os.NewSyscallError("CryptAcquireContext", err)
+		}
+	}
+	r.mu.Unlock()
+
+	if len(b) == 0 {
+		return 0, nil
+	}
+	err = syscall.CryptGenRandom(r.prov, uint32(len(b)), &b[0])
+	if err != nil {
+		return 0, os.NewSyscallError("CryptGenRandom", err)
+	}
+	return len(b), nil
+}