**Cryptography Tutorials - Herong's Tutorial Examples** - v5.42, by Herong Yang

What Is SHA1 Message Digest Algorithm?

This section describes what is SHA1 (Secure Hash Algorithm 1) - a message digest algorithm which takes as input a message of arbitrary length and produces as output a 160-bit 'fingerprint'.

SHA1 (Secure Hash Algorithm 1) is message-digest algorithm, which takes an input message of any length < 2^64 bits and produces a 160-bit output as the message digest.

Based on the SHA1 RFC document, the SHA-1 is called secure because it is computationally infeasible to find a message which corresponds to a given message digest, or to find two different messages which produce the same message digest. Any change to a message in transit will, with very high probability, result in a different message digest, and the signature will fail to verify.

The original specification of the algorithm was published in 1993 as the Secure Hash Standard, FIPS PUB 180, by US government standards agency NIST (National Institute of Standards and Technology). This version is now often referred to as "SHA0".

SHA-0 was withdrawn by the NSA shortly after publication and was superseded by the revised version, published in 1995 in FIPS PUB 180-1 and commonly referred to as "SHA1".

Table of Contents

Introduction to AES (Advanced Encryption Standard)

DES Algorithm - Illustrated with Java Programs

DES Algorithm Java Implementation

DES Algorithm - Java Implementation in JDK JCE

DES Encryption Operation Modes

PHP Implementation of DES - mcrypt

Blowfish - 8-Byte Block Cipher

Secret Key Generation and Management

Cipher - Secret Key Encryption and Decryption

RSA Implementation using java.math.BigInteger Class

Introduction of DSA (Digital Signature Algorithm)

Java Default Implementation of DSA

Private key and Public Key Pair Generation

PKCS#8/X.509 Private/Public Encoding Standards

Cipher - Public Key Encryption and Decryption

►SHA1 Mesasge Digest Algorithm

►What Is SHA1 Message Digest Algorithm?

SHA1 Message Digest Algorithm Overview

Using SHA1 Message Digest in Java

Using SHA1 Message Digest in PHP

Using SHA1 Message Digest in Perl

OpenSSL Introduction and Installation

OpenSSL Generating and Managing RSA Keys

OpenSSL Generating and Signing CSR

OpenSSL Validating Certificate Path

"keytool" and "keystore" from JDK

"OpenSSL" Signing CSR Generated by "keytool"

Migrating Keys from "keystore" to "OpenSSL" Key Files

Certificate X.509 Standard and DER/PEM Formats

Migrating Keys from "OpenSSL" Key Files to "keystore"