PKCS5 (RFC 1423) based [un]padding routines

padPKCS5 :: ByteLength -> ByteString -> ByteString Source

PKCS5 (aka RFC1423) padding method. This method will not work properly for pad modulos > 256

padBlockSize :: BlockCipher k => k -> ByteString -> ByteString Source

PKCS5 (aka RFC1423) padding method using the BlockCipher instance to determine the pad size.

putPaddedPKCS5 :: ByteLength -> ByteString -> Put Source

     putPaddedPKCS5 m bs

Will pad out bs to a byte multiple of m and put both the bytestring and it's padding via Put (this saves on copying if you are already using Cereal).

unpadPKCS5safe :: ByteString -> Maybe ByteString Source

unpad a strict bytestring padded in the typical PKCS5 manner. This routine verifies all pad bytes and pad length match correctly.

unpadPKCS5 :: ByteString -> ByteString Source

unpad a strict bytestring without checking the pad bytes and length any more than necessary.

ESP (RFC 4303) [un]padding routines

padESP :: Int -> ByteString -> ByteString Source

Pad a bytestring to the IPSEC esp specification

 padESP m payload

is equivilent to:

               (msg)       (padding)       (length field)
     B.concat [payload, B.pack [1,2,3,4..], B.pack [padLen]]

Where:

the msg is any payload, including TFC.
the padding is <= 255
the length field is one byte.

Notice the result bytesting length remainder r equals zero. The lack of a "next header" field means this function is not directly useable for an IPSec implementation (copy/paste the 4 line function and add in a "next header" field if you are making IPSec ESP).

unpadESP :: ByteString -> Maybe ByteString Source

A static espPad allows reuse of a single B.pack'ed pad for all calls to padESP

unpad and return the padded message (Nothing is returned if the padding is invalid)

padESPBlockSize :: BlockCipher k => k -> ByteString -> ByteString Source

Like padESP but use the BlockCipher instance to determine padding size

putPadESPBlockSize :: BlockCipher k => k -> ByteString -> Put Source

Like putPadESP but using the BlockCipher instance to determine padding size

putPadESP :: Int -> ByteString -> Put Source

Pad a bytestring to the IPSEC ESP specification using Put. This can reduce copying if you are already using Put.