SHA-1

1 General Description

SHA-1 is an iterated hash function. It can be used to compute a 160-bit hash value for messages having a length of less than bits, cf. FIPS 180-2 Secure Hash Standard. As most iterated hash functions, SHA-1 applies MD strengthening.

1.1 Compression Function

The compression function processes input message blocks of 512 bits and produces a 160-bit chaining value. The compression function of SHA-1 basically consists of two parts: the message expansion and the state update transformation. The chaining variable (iv in the first iteration) is added to the output of the state update transformation (feed forward). This is graphically illustrated in.

File:SHA1CompressionFunction.png

The SHA-1 compression function

1.1.1 Message Expansion

The message expansion is defined as follows:

1.1.2 State Update Transformation

1.3 Constantsand Initial Value

1.3.1 Constants

1.3.2 Initial Value

3 Security Anaylsis

• Best know attack: by Wang et.al.
• Best known collision example: 64-step collision by De Canniere and Rechberger

something like: best know attack to date: kind of attack, which variant has been looked at (e.g. round-reduced), complexity, and reference to paper and abstract.

may be make here a new page with the other cryptanalysis results.

• [Detailed overview of cryptanalysis results]