1 files changed, 87 insertions, 0 deletions
diff --git a/src/crypto/rand/rand_plan9.go b/src/crypto/rand/rand_plan9.go
new file mode 100644
index 0000000..5d0af09
--- /dev/null
+++ b/src/crypto/rand/rand_plan9.go
@@ -0,0 +1,87 @@
+// 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.
+
+// Plan9 cryptographically secure pseudorandom number
+// generator.
+
+package rand
+
+import (
+	"crypto/aes"
+	"encoding/binary"
+	"io"
+	"os"
+	"sync"
+	"time"
+)
+
+const randomDevice = "/dev/random"
+
+func init() {
+	Reader = &reader{}
+}
+
+// reader is a new pseudorandom generator that seeds itself by
+// reading from /dev/random. The Read method on the returned
+// reader always returns the full amount asked for, or else it
+// returns an error. The generator is a fast key erasure RNG.
+type reader struct {
+	mu      sync.Mutex
+	seeded  sync.Once
+	seedErr error
+	key     [32]byte
+}
+
+func (r *reader) Read(b []byte) (n int, err error) {
+	r.seeded.Do(func() {
+		t := time.AfterFunc(time.Minute, func() {
+			println("crypto/rand: blocked for 60 seconds waiting to read random data from the kernel")
+		})
+		defer t.Stop()
+		entropy, err := os.Open(randomDevice)
+		if err != nil {
+			r.seedErr = err
+			return
+		}
+		_, r.seedErr = io.ReadFull(entropy, r.key[:])
+	})
+	if r.seedErr != nil {
+		return 0, r.seedErr
+	}
+
+	r.mu.Lock()
+	blockCipher, err := aes.NewCipher(r.key[:])
+	if err != nil {
+		r.mu.Unlock()
+		return 0, err
+	}
+	var (
+		counter uint64
+		block   [aes.BlockSize]byte
+	)
+	inc := func() {
+		counter++
+		if counter == 0 {
+			panic("crypto/rand counter wrapped")
+		}
+		binary.LittleEndian.PutUint64(block[:], counter)
+	}
+	blockCipher.Encrypt(r.key[:aes.BlockSize], block[:])
+	inc()
+	blockCipher.Encrypt(r.key[aes.BlockSize:], block[:])
+	inc()
+	r.mu.Unlock()
+
+	n = len(b)
+	for len(b) >= aes.BlockSize {
+		blockCipher.Encrypt(b[:aes.BlockSize], block[:])
+		inc()
+		b = b[aes.BlockSize:]
+	}
+	if len(b) > 0 {
+		blockCipher.Encrypt(block[:], block[:])
+		copy(b, block[:])
+	}
+	return n, nil
+}