Crypto.Padding

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

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

Ex:

    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).

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

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

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).

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

Like padESP but use the BlockCipher instance to determine padding size

Like putPadESP but using the BlockCipher instance to determine padding size

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