crypto: chacha20poly1305 - Skip encryption/decryption for 0-len
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>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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 @@
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 @@
if (err)
return err;
+skip:
return poly_verify_tag(req);
}
@@ -415,6 +419,9 @@
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 @@
if (err)
return err;
+skip:
return poly_genkey(req);
}