From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Daniel Micay Date: Wed, 9 Sep 2020 01:53:11 -0400 Subject: [PATCH] pad filenames to 32 bytes instead of 16 or 4 bytes This was adopted before the earliest stable release of GrapheneOS, so backwards compatibility is not implemented anymore. --- libfscrypt/fscrypt.cpp | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-) diff --git a/libfscrypt/fscrypt.cpp b/libfscrypt/fscrypt.cpp index a52ed90c..7852349f 100644 --- a/libfscrypt/fscrypt.cpp +++ b/libfscrypt/fscrypt.cpp @@ -228,17 +228,8 @@ bool ParseOptionsForApiLevel(unsigned int first_api_level, const std::string& op } } - // In the original setting of v1 policies and AES-256-CTS we used 4-byte - // padding of filenames, so retain that on old first_api_levels. - // - // For everything else, use 16-byte padding. This is more secure (it helps - // hide the length of filenames), and it makes the inputs evenly divisible - // into cipher blocks which is more efficient for encryption and decryption. - if (!is_gki && options->version == 1 && options->filenames_mode == FSCRYPT_MODE_AES_256_CTS) { - options->flags |= FSCRYPT_POLICY_FLAGS_PAD_4; - } else { - options->flags |= FSCRYPT_POLICY_FLAGS_PAD_16; - } + // GrapheneOS has always used the maximum 32 byte padding. + options->flags |= FSCRYPT_POLICY_FLAGS_PAD_32; // Use DIRECT_KEY for Adiantum, since it's much more efficient but just as // secure since Android doesn't reuse the same master key for multiple