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crypto: chacha20poly1305 - Skip encryption/decryption for 0-len

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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>
This commit is contained in:
Jason A. Donenfeld 2015-12-06 02:51:38 +01:00 committed by Herbert Xu
parent 3d5b1ecdea
commit 161151d79f
1 changed files with 8 additions and 0 deletions
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8
crypto/chacha20poly1305.c
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@ -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);
}