# SHA-1

From The ECRYPT Hash Function Website

## Contents

## 1 General Description

SHA-1 is an iterated hash function.

### 1.1 Compression Function

The compression function takes as input a 512-bit message block and a 160-bit chaining variable, and produces a 160-bit chaining value. The compression function is described as follows:

#### 1.1.1 Message Expansion

#### 1.1.2 State Update Transformation

<math>

A_{i+1} = A_i << 5 + W_i + f(B_i,C_i,D_i) + K_i

</math>

<math>

B_{i+1} = A_i

</math>

<math>

C_{i+1} = B_i >> 2

</math>

<math>

D_{i+1} = C_i

</math>

<math>

E_{i+1} = D_i

</math>

### 1.2 Padding Method

### 1.3 Initial Value and Constants

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## 2 Claimed Security Margins

## 3 Security Anaylsis

- Best know attack: <math>2^{63}</math> 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.