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WOLFSSL_AES_CBC_LENGTH_CHECKS: add gated logic to aes.c wc_AesCbc{En,De}crypt() to return BAD_LENGTH_E when input length is not a multiple of AES_BLOCK_SIZE; add gated tests of new functionality in test_wc_AesCbcEncryptDecrypt(); fix first encrypt-decrypt-memcmp in test_wc_AesCbcEncryptDecrypt() to span all of test vector and extend test vector length to be block-multiple; add ungated logic in platform-specific wc_AesCbc{En,De}crypt() routines to return with early success when blocks == 0 (also mitigates buffer overrun on short (less-than-AES_BLOCK_SIZE) input); add BAD_LENGTH_E error code; update documentation.

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This commit is contained in:
Daniel Pouzzner
2021-03-25 17:52:01 -05:00
parent f201d65459
commit 5d9ee97530
5 changed files with 168 additions and 25 deletions
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28
doc/dox_comments/header_files/aes.h
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@@ -66,16 +66,22 @@ WOLFSSL_API int wc_AesSetIV(Aes* aes, const byte* iv);
the resulting cipher text in the output buffer out using cipher block
chaining with AES. This function requires that the AES object has been
initialized by calling AesSetKey before a message is able to be encrypted.
This function assumes that the input message is AES block length aligned.
PKCS#7 style padding should be added beforehand. This differs from the
OpenSSL AES-CBC methods which add the padding for you. To make the wolfSSL
function and equivalent OpenSSL functions interoperate, one should specify
This function assumes that the input message is AES block length aligned,
and expects the input length to be a multiple of the block length, which
will optionally be checked and enforced if WOLFSSL_AES_CBC_LENGTH_CHECKS
is defined in the build configuration. In order to assure block-multiple
input, PKCS#7 style padding should be added beforehand. This differs from
the OpenSSL AES-CBC methods which add the padding for you. To make the
wolfSSL and corresponding OpenSSL functions interoperate, one should specify
the -nopad option in the OpenSSL command line function so that it behaves
like the wolfSSL AesCbcEncrypt method and does not add extra padding
during encryption.
\return 0 On successfully encrypting message.
\return BAD_ALIGN_E: Returned on block align error
\return BAD_ALIGN_E: may be returned on block align error
\return BAD_LENGTH_E will be returned if the input length isn't a
multiple of the AES block length, when the library is built with
WOLFSSL_AES_CBC_LENGTH_CHECKS.
\param aes pointer to the AES object used to encrypt data
\param out pointer to the output buffer in which to store the ciphertext
@@ -110,15 +116,21 @@ WOLFSSL_API int wc_AesCbcEncrypt(Aes* aes, byte* out,
with AES. This function requires that the AES structure has been
initialized by calling AesSetKey before a message is able to be decrypted.
This function assumes that the original message was AES block length
aligned. This differs from the OpenSSL AES-CBC methods which do not
require alignment as it adds PKCS#7 padding automatically. To make the
aligned, and expects the input length to be a multiple of the block length,
which will optionally be checked and enforced if
WOLFSSL_AES_CBC_LENGTH_CHECKS is defined in the build configuration.
This differs from the OpenSSL AES-CBC methods, which add PKCS#7 padding
automatically, and so do not require block-multiple input. To make the
wolfSSL function and equivalent OpenSSL functions interoperate, one
should specify the -nopad option in the OpenSSL command line function
so that it behaves like the wolfSSL AesCbcEncrypt method and does not
create errors during decryption.
\return 0 On successfully decrypting message.
\return BAD_ALIGN_E Returned on block align error.
\return BAD_ALIGN_E may be returned on block align error.
\return BAD_LENGTH_E will be returned if the input length isn't a
multiple of the AES block length, when the library is built with
WOLFSSL_AES_CBC_LENGTH_CHECKS.
\param aes pointer to the AES object used to decrypt data.
\param out pointer to the output buffer in which to store the plain text