diff options
| author | Andrey Andreev <narf@devilix.net> | 2014-07-02 18:09:08 +0200 |
|---|---|---|
| committer | Andrey Andreev <narf@devilix.net> | 2014-07-02 18:09:08 +0200 |
| commit | ab9971f112c1394db0d0fc963d860479d3ec408b (patch) | |
| tree | d1b01df4b07c54ba36cc27db333030035812294a /user_guide_src | |
| parent | 961db7dd3843ee7acba3557d4c82c2cd8ab9e937 (diff) | |
Remove GCM mode from CI_Encryption (OpenSSL)
While openssl_get_cipher_methods() lists 'aes-<keysize>-gcm' as supported,
it appears that this is only half of the story. To be more specific, only
the encryption operation of GCM is performed, and the authentication message
is completely missing, rendering the whole thing useles.
Diffstat (limited to 'user_guide_src')
| -rw-r--r-- | user_guide_src/source/libraries/encryption.rst | 17 |
1 files changed, 6 insertions, 11 deletions
diff --git a/user_guide_src/source/libraries/encryption.rst b/user_guide_src/source/libraries/encryption.rst index 1353c4ed0..5d92b109a 100644 --- a/user_guide_src/source/libraries/encryption.rst +++ b/user_guide_src/source/libraries/encryption.rst @@ -173,9 +173,9 @@ but regardless, here's a list of most of them: ============== ========= ============================== ========================================= Cipher name Driver Key lengths (bits / bytes) Supported modes ============== ========= ============================== ========================================= -AES-128 OpenSSL 128 / 16 CBC, CTR, CFB, CFB8, OFB, ECB, GCM, XTS -AES-192 OpenSSL 192 / 24 CBC, CTR, CFB, CFB8, OFB, ECB, GCM, XTS -AES-256 OpenSSL 256 / 32 CBC, CTR, CFB, CFB8, OFB, ECB, GCM, XTS +AES-128 OpenSSL 128 / 16 CBC, CTR, CFB, CFB8, OFB, ECB, XTS +AES-192 OpenSSL 192 / 24 CBC, CTR, CFB, CFB8, OFB, ECB, XTS +AES-256 OpenSSL 256 / 32 CBC, CTR, CFB, CFB8, OFB, ECB, XTS Rijndael-128 MCrypt 128 / 16, 192 / 24, 256 / 32 CBC, CTR, CFB, CFB8, OFB, OFB8, ECB Rijndael-192 MCrypt 128 / 16, 192 / 24, 256 / 32 CBC, CTR, CFB, CFB8, OFB, OFB8, ECB Rijndael-256 MCrypt 128 / 16, 192 / 24, 256 / 32 CBC, CTR, CFB, CFB8, OFB, OFB8, ECB @@ -239,7 +239,6 @@ CFB8 cfb8 MCrypt, OpenSSL Same as CFB, but operates in 8- OFB ofb MCrypt, OpenSSL N/A OFB8 ofb8 MCrypt Same as OFB, but operates in 8-bit mode (not recommended). ECB ecb MCrypt, OpenSSL Ignores IV (not recommended). -GCM gcm OpenSSL Provides authentication and therefore doesn't need a HMAC. XTS xts OpenSSL Usually used for encrypting random access data such as RAM or hard-disk storage. Stream stream MCrypt, OpenSSL This is not actually a mode, it just says that a stream cipher is being used. Required because of the general cipher+mode initialization process. =========== ================== ================= =================================================================================================================================================== @@ -251,10 +250,9 @@ It's probably important for you to know that an encrypted string is usually longer than the original, plain-text string (depending on the cipher). This is influenced by the cipher algorithm itself, the IV prepended to the -cipher-text and (unless you are using GCM mode) the HMAC authentication -message that is also prepended. Furthermore, the encrypted message is also -Base64-encoded so that it is safe for storage and transmission, regardless -of a possible character set in use. +cipher-text and the HMAC authentication message that is also prepended. +Furthermore, the encrypted message is also Base64-encoded so that it is safe +for storage and transmission, regardless of a possible character set in use. Keep this information in mind when selecting your data storage mechanism. Cookies, for example, can only hold 4K of information. @@ -446,9 +444,6 @@ raw_data FALSE No Whether the cipher-t value is incorrect. This includes *hmac_key*, unless *hmac* is set to FALSE. -.. note:: If GCM mode is used, *hmac* will always be FALSE. This is - because GCM mode itself provides authentication. - .. _digests: Supported HMAC authentication algorithms |