Generating the SHA hash of a string using golang

hash go

Can someone show me a working example of how to generate a SHA hash of a string that I have, say myPassword := "beautiful" , using Go 1 ?

The docs pages lack examples and I could not find any working code on Google.

An example :

import (
    "crypto/sha1"
    "encoding/base64"
)

func (ms *MapServer) storee(bv []byte) {
    hasher := sha1.New()
    hasher.Write(bv)
    sha := base64.URLEncoding.EncodeToString(hasher.Sum(nil))
        ...
}

In this example I make a sha from a byte array. You can get the byte array using

bv := []byte(myPassword)

Of course you don't need to encode it in base64 if you don't have to : you may use the raw byte array returned by the Sum function.

There seems to be some little confusion in comments below. So let's clarify for next users the best practices on conversions to strings:

you never store a SHA as a string in a database, but as raw bytes
when you want to display a SHA to a user, a common way is Hexadecimal
when you want a string representation because it must fit in an URL or in a filename, the usual solution is Base64, which is more compact

Go By Example has a page on sha1 hashing.

package main

import (
    "fmt"
    "crypto/sha1"
    "encoding/hex"
)

func main() {

    s := "sha1 this string"
    h := sha1.New()
    h.Write([]byte(s))
    sha1_hash := hex.EncodeToString(h.Sum(nil))

    fmt.Println(s, sha1_hash)
}

You can run this example on play.golang.org

The package documentation at http://golang.org/pkg/crypto/sha1/ does have an example that demonstrates this. It's stated as an example of the New function, but it's the only example on the page and it has a link right near the top of the page so it is worth looking at. The complete example is,

Code:

h := sha1.New()
io.WriteString(h, "His money is twice tainted: 'taint yours and 'taint mine.")
fmt.Printf("% x", h.Sum(nil))

Output:

59 7f 6a 54 00 10 f9 4c 15 d7 18 06 a9 9a 2c 87 10 e7 47 bd

You can actually do this in a much more concise and idiomatic manner:

// Assuming 'r' is set to some inbound net/http request
form_value := []byte(r.PostFormValue("login_password"))
sha1_hash := fmt.Sprintf("%x", sha1.Sum(form_value))

// Then output optionally, to test
fmt.Println(sha1_hash)

In this trivial example of a http.Request POST containing a login_password field, it is worth noting that fmt.Sprintf() called with %x converted the hash value to hex without having to include an import "encoding/hex" declaration.

( We used fmt.Sprintf() as opposed to fmt.Printf() as we were outputting a string to a variable assignment, not an io.Writer interface. )

Also of reference, is that the sha1.Sum() function verbosely instantiates in the same manner as the sha1.New() definition:

func New() hash.Hash {
    d := new(digest)
    d.Reset()
    return d
}

func Sum(data []byte) [Size]byte {
    var d digest
    d.Reset()
    d.Write(data)
    return d.checkSum()
}

This holds true ( at least at the time of posting ) for the Sha library variants in Golang's standard crypto set, such as Sha512.

Lastly, if one wanted to, they could follow Golang's [to]String() implementation with something like func (h hash.Hash) String() string {...} to encapsulate the process.

That is most likely beyond the desired scope of the original question.

h := sha1.New()
h.Write(content)
sha := h.Sum(nil)  // "sha" is uint8 type, encoded in base16

shaStr := hex.EncodeToString(sha)  // String representation

fmt.Printf("%x\n", sha)
fmt.Println(shaStr)

Generating the SHA hash of a string using golang

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