One-way compression function: Difference between revisions

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[[Image:Davies-Meyer hash.svg|thumb|230px|right|The Davies–Meyer one-way compression function]]

The Davies–Meyer single-block-length compression function feeds each block of the message (<math>m_i</math>) as the key to a block cipher. It feeds the previous hash value (<math>H_{i-1}</math>) as the plaintext to be encrypted. The output ciphertext is then also [[exclusive-or|XORed]] (⊕) with the previous hash value (<math>H_{i-1}</math>) to produce the next hash value (<math>H_i</math>). In the first round when there is no previous hash value it uses a constant pre-specified initial value (<math>H_0</math>).

In [[mathematical notation]] Davies–Meyer can be described as: