[edflsafoiewq]

AFAIK the 1 bit does nothing. Padding with 1+(number of 0s)+(length of message) is traditional though and used by MD4/MD5/SHA1/SHA2.

You can read in a few places that this is the padding proposed by Merkle, but I looked it up and in my reading of One Way Hash Functions and DES he does not use the 1

> As an aside, we note that x is padded with 0's until its size is an integral multiple of the size of the convenientlySizedChunks. Note that padding with 0s might introduce some ambiguity about the exact value of x that is being authenticated, as discussed by Juenernan[4]. The message "010110" padded to 8 bits would be "01011000" and it is now unclear how many trailing 0's were present in the original message. Several methods are available to resolve this ambiguity. We select a method that will also be useful in resolving a further problem: we append the length of x, in bits, at the end of x. To make this additional "length" field easy to find. we shall right justify it in the final block. If the length field won't fit, we add additional blocks to the end of x.