Davies-meyer in VHDL

Discussion in 'VHDL' started by Adam, Aug 22, 2006.

  1. Adam

    Adam Guest

    Hi everybody;

    I am new in VDHL and crypto also. I would like to implement the
    Davies-meyer HASH function ( Hi = Emi(Hi-1)+Hi-1 ) in VHDL. The problem
    I am having is that: The block cipher I am having (Kasumi) have 64 bits
    input and output and the HASH function(SHA1) is having 160 bits output.
    I don't know how can I manage an agrement between them in order to
    implement the Davies-meyer.
    Can anyone help me in getting an arrangement of those functions or
    indicate where I can find literatures or implementations about this.
    Thanks all and nice day.
    Adam.
    Adam, Aug 22, 2006
    #1
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  2. Adam

    ajjc Guest

    Adam,
    I'm confused by your use of SHA1 in your post. Perhaps looking at

    http://en.wikipedia.org/wiki/Hash_functions_based_on_block_ciphers

    and rephrasing your question would help me understand what you want.

    This method(Davies-Meyer) takes a block cipher and creates
    a hash fucntion from it. The key size of the block cipher is the size
    of the message block being hashed, whereas the message block size of
    the stream cipher is the hash value size.

    alan

    Adam wrote:
    > Hi everybody;
    >
    > I am new in VDHL and crypto also. I would like to implement the
    > Davies-meyer HASH function ( Hi = Emi(Hi-1)+Hi-1 ) in VHDL. The problem
    > I am having is that: The block cipher I am having (Kasumi) have 64 bits
    > input and output and the HASH function(SHA1) is having 160 bits output.
    > I don't know how can I manage an agrement between them in order to
    > implement the Davies-meyer.
    > Can anyone help me in getting an arrangement of those functions or
    > indicate where I can find literatures or implementations about this.
    > Thanks all and nice day.
    > Adam.
    ajjc, Aug 22, 2006
    #2
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  3. Adam

    Adam Guest

    ajjc schrieb:

    > Adam,
    > I'm confused by your use of SHA1 in your post. Perhaps looking at
    >
    > http://en.wikipedia.org/wiki/Hash_functions_based_on_block_ciphers
    >
    > and rephrasing your question would help me understand what you want.
    >
    > This method(Davies-Meyer) takes a block cipher and creates
    > a hash fucntion from it. The key size of the block cipher is the size
    > of the message block being hashed, whereas the message block size of
    > the stream cipher is the hash value size.
    >
    > alan


    Hi Alan,

    Thanks a lot; your message cleared a lot of confusions in my mind. I
    was actually miss-lead because I have been given a wrong Davies-meyer
    diagram containing a Hash function.
    Now everything is clear and once more thanks.

    Adam.
    Adam, Aug 22, 2006
    #3
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