| Message ID | 1449366698-2422-2-git-send-email-Jason@zx2c4.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Herbert Xu |
| Headers | show |
On Sun, Dec 06, 2015 at 02:51:38AM +0100, Jason A. Donenfeld wrote: > If the length of the plaintext is zero, there's no need to waste cycles > on encryption and decryption. Using the chacha20poly1305 construction > for zero-length plaintexts is a common way of using a shared encryption > key for AAD authentication. > > Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Patch applied. Thanks.
diff --git a/crypto/chacha20poly1305.c b/crypto/chacha20poly1305.c index 99c3cce..7b6b935 100644 --- a/crypto/chacha20poly1305.c +++ b/crypto/chacha20poly1305.c @@ -130,6 +130,9 @@ static int chacha_decrypt(struct aead_request *req) struct scatterlist *src, *dst; int err; + if (rctx->cryptlen == 0) + goto skip; + chacha_iv(creq->iv, req, 1); sg_init_table(rctx->src, 2); @@ -150,6 +153,7 @@ static int chacha_decrypt(struct aead_request *req) if (err) return err; +skip: return poly_verify_tag(req); } @@ -415,6 +419,9 @@ static int chacha_encrypt(struct aead_request *req) struct scatterlist *src, *dst; int err; + if (req->cryptlen == 0) + goto skip; + chacha_iv(creq->iv, req, 1); sg_init_table(rctx->src, 2); @@ -435,6 +442,7 @@ static int chacha_encrypt(struct aead_request *req) if (err) return err; +skip: return poly_genkey(req); }
If the length of the plaintext is zero, there's no need to waste cycles on encryption and decryption. Using the chacha20poly1305 construction for zero-length plaintexts is a common way of using a shared encryption key for AAD authentication. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Cc: <stable@vger.kernel.org> --- crypto/chacha20poly1305.c | 8 ++++++++ 1 file changed, 8 insertions(+)