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Fix the derivation of SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD.

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It happens to give the same value anyway (64 + 16), but only on accident.

Change-Id: I1415f4015e3de472dbeb9ada0d92607c9d1bcd40
Reviewed-on: https://boringssl-review.googlesource.com/3780
Reviewed-by: Adam Langley <agl@google.com>
This commit is contained in:
David Benjamin 2015-03-05 11:22:42 -08:00 committed by Adam Langley
parent a4e6d48749
commit f46cea8cd8
1 changed files with 16 additions and 5 deletions
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21
include/openssl/ssl3.h
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@ -117,9 +117,11 @@
#ifndef HEADER_SSL3_H #ifndef HEADER_SSL3_H
#define HEADER_SSL3_H #define HEADER_SSL3_H
#include <openssl/aead.h>
#include <openssl/buf.h> #include <openssl/buf.h>
#include <openssl/evp.h> #include <openssl/evp.h>
#include <openssl/ssl.h> #include <openssl/ssl.h>
#include <openssl/type_check.h>
#ifdef __cplusplus #ifdef __cplusplus
extern "C" { extern "C" {
@ -237,14 +239,23 @@ extern "C" {
/* The standards give a maximum encryption overhead of 1024 bytes. In practice /* The standards give a maximum encryption overhead of 1024 bytes. In practice
* the value is lower than this. The overhead is the maximum number of padding * the value is lower than this. The overhead is the maximum number of padding
* bytes (256) plus the mac size. */ * bytes (256) plus the mac size.
*
* TODO(davidben): This derivation doesn't take AEADs into account, or TLS 1.1
* explicit nonces. It happens to work because |SSL3_RT_MAX_MD_SIZE| is larger
* than necessary and no true AEAD has variable overhead in TLS 1.2. */
#define SSL3_RT_MAX_ENCRYPTED_OVERHEAD (256 + SSL3_RT_MAX_MD_SIZE) #define SSL3_RT_MAX_ENCRYPTED_OVERHEAD (256 + SSL3_RT_MAX_MD_SIZE)
/* OpenSSL currently only uses a padding length of at most one block so the /* SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD is the maximum overhead in encrypting a
* send overhead is smaller. */ * record. This does not include the record header. Some ciphers use explicit
* nonces, so it includes both the AEAD overhead as well as the nonce. */
#define SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD \ #define SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD \
(SSL_RT_MAX_CIPHER_BLOCK_SIZE + SSL3_RT_MAX_MD_SIZE) (EVP_AEAD_MAX_OVERHEAD + EVP_AEAD_MAX_NONCE_LENGTH)
OPENSSL_COMPILE_ASSERT(
SSL3_RT_MAX_ENCRYPTED_OVERHEAD >= SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD,
max_overheads_are_consistent);
/* If compression isn't used don't include the compression overhead */ /* If compression isn't used don't include the compression overhead */