crypto/rsa: change public exponent from 3 to 65537

Although there's still no concrete security reason not to use 3, I
think Bleichenbacher has convinced me that it's a useful defense and
it's what everyone else does.

R=bradfitz, rsc
CC=golang-dev
https://golang.org/cl/5307060

diff --git a/src/pkg/crypto/rsa/rsa.go b/src/pkg/crypto/rsa/rsa.go
index 6957659f2843052fd3511f3d0847b2d597760ec3..3df88e06915a849c70c16e03c3d126566cefd1a5 100644 (file)
--- a/src/pkg/crypto/rsa/rsa.go
+++ b/src/pkg/crypto/rsa/rsa.go
@@ -116,15 +116,7 @@ func GenerateKey(random io.Reader, bits int) (priv *PrivateKey, err os.Error) {
 // [2] http://www.cacr.math.uwaterloo.ca/techreports/2006/cacr2006-16.pdf
 func GenerateMultiPrimeKey(random io.Reader, nprimes int, bits int) (priv *PrivateKey, err os.Error) {
        priv = new(PrivateKey)
-       // Smaller public exponents lead to faster public key
-       // operations. Since the exponent must be coprime to
-       // (p-1)(q-1), the smallest possible value is 3. Some have
-       // suggested that a larger exponent (often 2**16+1) be used
-       // since previous implementation bugs[1] were avoided when this
-       // was the case. However, there are no current reasons not to use
-       // small exponents.
-       // [1] http://marc.info/?l=cryptography&m=115694833312008&w=2
-       priv.E = 3
+       priv.E = 65537
 
        if nprimes < 2 {
                return nil, os.NewError("rsa.GenerateMultiPrimeKey: nprimes must be >= 2")