Bernhard Rosenkraenzer | c83ebe5 | 2012-09-18 21:38:03 +0159 | [diff] [blame] | 1 | // Copyright 2010 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | // Windows cryptographically secure pseudorandom number |
| 6 | // generator. |
| 7 | |
| 8 | package rand |
| 9 | |
| 10 | import ( |
| 11 | "os" |
| 12 | "sync" |
| 13 | "syscall" |
| 14 | ) |
| 15 | |
| 16 | // Implemented by using Windows CryptoAPI 2.0. |
| 17 | |
| 18 | func init() { Reader = &rngReader{} } |
| 19 | |
| 20 | // A rngReader satisfies reads by reading from the Windows CryptGenRandom API. |
| 21 | type rngReader struct { |
| 22 | prov syscall.Handle |
| 23 | mu sync.Mutex |
| 24 | } |
| 25 | |
| 26 | func (r *rngReader) Read(b []byte) (n int, err error) { |
| 27 | r.mu.Lock() |
| 28 | if r.prov == 0 { |
| 29 | const provType = syscall.PROV_RSA_FULL |
| 30 | const flags = syscall.CRYPT_VERIFYCONTEXT | syscall.CRYPT_SILENT |
| 31 | err := syscall.CryptAcquireContext(&r.prov, nil, nil, provType, flags) |
| 32 | if err != nil { |
| 33 | r.mu.Unlock() |
| 34 | return 0, os.NewSyscallError("CryptAcquireContext", err) |
| 35 | } |
| 36 | } |
| 37 | r.mu.Unlock() |
Bernhard Rosenkraenzer | ee2ec6d | 2012-10-10 01:40:27 +0159 | [diff] [blame^] | 38 | |
| 39 | if len(b) == 0 { |
| 40 | return 0, nil |
| 41 | } |
Bernhard Rosenkraenzer | c83ebe5 | 2012-09-18 21:38:03 +0159 | [diff] [blame] | 42 | err = syscall.CryptGenRandom(r.prov, uint32(len(b)), &b[0]) |
| 43 | if err != nil { |
| 44 | return 0, os.NewSyscallError("CryptGenRandom", err) |
| 45 | } |
| 46 | return len(b), nil |
| 47 | } |