golang中的检验hash
1.对字符串进行hash大家可以看一下， SHA1 Hashes
Go by Example写道：
The pattern for generating a hash is sha1.New(), sha1.Write(bytes), then sha1.Sum([]byte{}).
附上golang代码
package main
import (
"crypto/sha1"
"fmt"
)
func main() {
s := "sha1 this string"
h := sha1.New()
h.Write([]byte(s))
bs := h.Sum(nil)
fmt.Println(s)
fmt.Printf("%x\n", bs)
}
结果输出为：
sha1 this string
cf23df2207d99a74fbe169e3eba035e633b65d94
而在godoc产生的文档使用io:WriteString代替sha1.Write()，测试2种方法都可以用。
有些文档说，使用io:WriteString，意思更加明显，而且不用像上面要进行类型转换。
h := sha1.New()
io.WriteString(h
, "His money is twice tainted: 'taint yours and 'taint mine.")
fmt.Printf(
"% x", h.Sum(nil))
说个有趣的现象，使用上面代码产生的hash值和命令行中sha1sum的值不一致。
$echo "sha1 this string" | sha1sum
0faabfb58d5c522f47944173f2953f40ecfc2975
-
$
$
cat a.txt
sha1 this
string
$sha1sum a.txt
0faabfb58d5c522f47944173f2953f40ecfc2975a.txt
$
可以看到，上面2个结果是一致的，但与我们上面golang代码的输出不一致。
原因是，命令行echo会在字符串后面添加一个换行符，导致整个hash值变化。大家可以自行在golang的代码中，在验证的字符串中添加换行符测试看看。
2.对文本进行hash
参考 google论坛
模式是，os.Open(file), io.Copy(dst,src), sha1.Sum()
摘录2个github代码，代码在原来的基础上有修改。
go md5/sha1 example
/*
Hash - Guillermo Estrada
Simple utility to obtain the MD5 and/or SHA-
1
of a file from the command line.
package main
import (
"io"
"os"
"fmt"
"flag"
"crypto/md5"
"crypto/sha1"
)
func main() {
md5f := flag.Bool("md5", false, "-md5 calculate md5 hash of file")
sha1f := flag.Bool("sha1", false, "-sha1 calculate sha1 hash of file")
flag.Parse()
if !*md5f && !*sha1f {
fmt.Println("err: No hash specified. Use -md5 or -sha1 or both.")
os.Exit(1)
}
infile, inerr := os.Open(flag.Arg(0))
if inerr == nil {
if *md5f {
md5h := md5.New()
io.Copy(md5h,infile)
fmt.Printf("%x%s\n",md5h.Sum(nil), flag.Arg(0))
}
if *sha1f {
sha1h := sha1.New()
io.Copy(sha1h,infile)
fmt.Printf("%x%s\n",sha1h.Sum(nil), flag.Arg(0))
}
} else {
fmt.Println(inerr)
os.Exit(1)
}
}
命令行调用：
#for a in md5 sha1 ; do echo ${a}sum; ./hash -$a /bin/ls; ${a}sum /bin/ls; echo; done
md5sum
b691e28e120f6989e37c7db21cb51931
/bin/ls
b691e28e120f6989e37c7db21cb51931
/bin/ls
sha1sum
502202e177bb8677c8c3b059cc1401d1524806c8
/bin/ls
502202e177bb8677c8c3b059cc1401d1524806c8
/bin/ls
#
hashes.go
/*
Hash - Guillermo Estrada
Simple utility to obtain the MD5 and/or SHA-
1
of a file from the command line.
2011
Edited: Marko Mikulicic
2011
*/
package main
import (
"io"
"os"
"fmt"
"flag"
"hash"
"crypto/md5"
"crypto/sha1"
"crypto/sha256"
"crypto/sha512"
//"crypto/ripemd160"
)
func main() {
algos := [...]string{"md5", "sha1", "sha256", "sha512" }
impls := [...]hash.Hash{md5.New(), sha1.New(), sha256.New(), sha512.New() }
flags := make([]*bool, len(algos))
for i, a := range algos {
flags = flag.Bool(a, false, fmt.Sprintf("-%s calculate %s hash of file", a, a))
}
flag.Parse()
any := false
for _, f := range flags {
any = any || *f
}
if any == false {
fmt.Println("err: No hash specified. Please run with --help to see list of supported hash algos")
os.Exit(1)
}
infile, err := os.Open(flag.Arg(0))
if err != nil {
fmt.Println(err)
os.Exit(1)
}
writers := make([]io.Writer, 0, len(impls))
for i, flag := range flags {
if *flag {
writers = append(writers, impls)
}
}
dest := io.MultiWriter(writers...)
io.Copy(dest, infile)
for i, flag := range flags {
if *flag {
fmt.Printf("%s: \n%x\n", algos, impls.Sum(nil))
}
}
}
命令行调用：
#for a in md5 sha1 sha256 sha512 ; do ./hashes -$a /bin/ls; ${a}sum /bin/ls; echo; done
md5:
b691e28e120f6989e37c7db21cb51931
b691e28e120f6989e37c7db21cb51931
/bin/ls
sha1:
502202e177bb8677c8c3b059cc1401d1524806c8
502202e177bb8677c8c3b059cc1401d1524806c8
/bin/ls
sha256:
1e87d99599ddea2a93f060b50a54066e8b756d752158e6147cbb99b06eb11d99
1e87d99599ddea2a93f060b50a54066e8b756d752158e6147cbb99b06eb11d99
/bin/ls
sha512:
343b38486ad17c5813026c9df7e1ce7e268d7c64e70439aebddcafdfe10a0dfc9f55bf8169c3e592942f50bb408a852dfd1fb08e0bcadf214bc89dbf72d693f8
343b38486ad17c5813026c9df7e1ce7e268d7c64e70439aebddcafdfe10a0dfc9f55bf8169c3e592942f50bb408a852dfd1fb08e0bcadf214bc89dbf72d693f8
/bin/ls
#
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