SHA-1(Secure Hash Algorithm)是美国国家标准局(National Institute of Standard and Technology NIST)为了配合数位签章演算法(Digital Signature Algorithm DSA)的使用所发布的联邦资讯处理标准-FIPS PUB 180-1(Federal Information Processing Standard Publication 180-1),而SHA-1 则是SHA-1 (FIPS180)的改良版,现今与MD5 皆广被使用拿来做密码验证功能.其设计的方法是根据MD4,来对输入的资料讯息(Message)产生出一个160 位元的讯息摘要(Digest) ,对於资料安全性提供了有效的保障.-SHA-1 (Secure Hash Algorithm) is a United States National Bureau of Standards (National Institute of Standard and Technology NIST) in order to tie in with the digital signature algorithm (Digital Signature Algorithm DSA) issued by the use of Federal Information Processing Standard-FIPS PUB 180-1 (Federal Information Processing Standard Publication 180-1), and SHA-1 is SHA-1 (FIPS180) improved version of the current and MD5 are widely used to make the use of password authentication function. its design method is based on MD4, to the input data message (Message) produced a 160-bit message digest (Digest), for data security to provide effective protection.