diff options
Diffstat (limited to 'src/crypto/rsa/rsa.go')
| -rw-r--r-- | src/crypto/rsa/rsa.go | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/src/crypto/rsa/rsa.go b/src/crypto/rsa/rsa.go index 0715421187..9342930dc1 100644 --- a/src/crypto/rsa/rsa.go +++ b/src/crypto/rsa/rsa.go @@ -43,6 +43,10 @@ import ( var bigOne = big.NewInt(1) // A PublicKey represents the public part of an RSA key. +// +// The value of the modulus N is considered secret by this library and protected +// from leaking through timing side-channels. However, neither the value of the +// exponent E nor the precise bit size of N are similarly protected. type PublicKey struct { N *big.Int // modulus E int // public exponent @@ -478,10 +482,6 @@ var ErrMessageTooLong = errors.New("crypto/rsa: message too long for RSA key siz func encrypt(pub *PublicKey, plaintext []byte) ([]byte, error) { boring.Unreachable() - // Most of the CPU time for encryption and verification is spent in this - // NewModulusFromBig call, because PublicKey doesn't have a Precomputed - // field. If performance becomes an issue, consider placing a private - // sync.Once on PublicKey to compute this. N, err := bigmod.NewModulusFromBig(pub.N) if err != nil { return nil, err @@ -492,7 +492,7 @@ func encrypt(pub *PublicKey, plaintext []byte) ([]byte, error) { } e := uint(pub.E) - return bigmod.NewNat().ExpShort(m, e, N).Bytes(N), nil + return bigmod.NewNat().ExpShortVarTime(m, e, N).Bytes(N), nil } // EncryptOAEP encrypts the given message with RSA-OAEP. @@ -686,7 +686,7 @@ func decrypt(priv *PrivateKey, ciphertext []byte, check bool) ([]byte, error) { } if check { - c1 := bigmod.NewNat().ExpShort(m, uint(priv.E), N) + c1 := bigmod.NewNat().ExpShortVarTime(m, uint(priv.E), N) if c1.Equal(c) != 1 { return nil, ErrDecryption } |