Go 中的 OpenPGP 错误：“加密：请求的哈希函数不可用”

Question

我正在玩Go的openpgp包，方法是制作一个简单的程序来加密一条短消息并用 ASCII 码来保护它。我目前拥有的代码是：package mainimport (    "code.google.com/p/go.crypto/openpgp"    "code.google.com/p/go.crypto/openpgp/armor"    "fmt"    "log"    "os")func main() {    to, err := openpgp.NewEntity("John Smith", "comment", "[e-mail]", nil)    if err != nil {        log.Fatal(err)    }    from, err := openpgp.NewEntity("John Smith", "comment", "[e-mail]", nil)    if err != nil {        log.Fatal(err)    }    recipients := []*openpgp.Entity{to}    armorer, err := armor.Encode(os.Stdout, "PGP MESSAGE", nil)    if err != nil {        log.Fatal(err)    }    defer armorer.Close()    encrypter, err := openpgp.Encrypt(armorer, recipients, from, nil, nil)    if err != nil {        log.Fatal(err)    }    defer encrypter.Close()    fmt.Fprintf(encrypter, "Hello! How are you?")}当我运行它时，我得到输出：-----BEGIN PGP MESSAGE-----wcBMA5iJWayscZQHAQgAvHQtyGxzyHJNYQlK7bcYZnWRm1gHsRRVZIgPTxtqnklpKgCYOuv5dtgqUXinJWZnk3DozR7xbMj/c9oSlifJ9FiPnTaLLOIVhv2Jf7w9ydh3oig3vpL8rI/ha9bOJsNdznt3/z1ZLVghPsrRGHO7LWUTWQUn/cgQZXr/z5CpGQP0TFlMcbBuuwE2ffplAGkBSQlXNRx1ZsY6T+MjajWwcik/CjJ/NnzRpURpXFIWc85xHQbUexQzEghyh4t5NEQhx9UvmLtnKPmwnhxX3s43Zcd1VtzSXc77giE08fSdIDdHeDClMno6jsoWhmubXZVXOHqf+z5euEcxvYyk16N/jdLgAeMBTSifCFR8YuGBmOFADONO/4/M1ye76+KyhsbF4KTgK+CW4Rjg4NLi0ubP1A===YD2p-----END PGP MESSAGE-----panic: crypto: requested hash function is unavailablegoroutine 1 [running]:crypto.Hash.New(0x9, 0x21027c4b0, 0x1d3300)        /usr/local/Cellar/go/1.1.1/src/pkg/crypto/crypto.go:62 +0xabcode.google.com/p/go.crypto/openpgp.Encrypt(0x210299e70, 0x2102e76e0, 0x2210284f38, 0x1, 0x1, ...)        /Users/cb/workspace/go/src/code.google.com/p/go.crypto/openpgp/write.go:289 +0x1141main.main()        /Users/cb/workspace/go/src/github.com/xoebus/gpg/go-gpg.go:31 +0x425exit status 2看起来它正在输出装甲密文（似乎无效）然后崩溃，因为它找不到链接到二进制文件的注册哈希函数。据我所知，默认情况下它应该使用标准库中的一个 SHA 哈希值，这绝对应该被链接？我究竟做错了什么？

Answer 1

散列函数必须由import _ "whatever". 不会自动链接到您的二进制文件中。实际上，没有明确（或可传递地）导入的内容。但是，如果您直接使用一些非导入的实体，编译器/链接器会抱怨。散列函数 OTOH 以及 stdlib 的其他一些部分通过散列接口使用一种后期绑定。

(09:25) jnml@fsc-r550:~/src/tmp/SO/17986762$ cat main.go 

package main

import (

        "fmt"

        "log"

        "os"

        "code.google.com/p/go.crypto/openpgp"

        "code.google.com/p/go.crypto/openpgp/armor"

        _ "code.google.com/p/go.crypto/ripemd160"

)

func main() {

        to, err := openpgp.NewEntity("John Smith", "comment", "[e-mail]", nil)

        if err != nil {

                log.Fatal(err)

        }

        from, err := openpgp.NewEntity("John Smith", "comment", "[e-mail]", nil)

        if err != nil {

                log.Fatal(err)

        }

        recipients := []*openpgp.Entity{to}

        armorer, err := armor.Encode(os.Stdout, "PGP MESSAGE", nil)

        if err != nil {

                log.Fatal(err)

        }

        defer armorer.Close()

        encrypter, err := openpgp.Encrypt(armorer, recipients, from, nil, nil)

        if err != nil {

                log.Fatal(err)

        }

        defer encrypter.Close()

        fmt.Fprintf(encrypter, "Hello! How are you?")

}

(09:25) jnml@fsc-r550:~/src/tmp/SO/17986762$ go run main.go 

-----BEGIN PGP MESSAGE-----

wcBMA6art6sLA/RNAQgAyScgc5RZErJ59rFreeOiotvMcSDgIRgdoxyKjo7qHxhz

jwhxYv/fqLgpYq5AbOCXVUK4Ubt+vmr+ET/txhW5tCx96cTZXVmyuke89+yQ6SQ7

ESlZxq9X973lpOq/I1rXY6T8bgfz4TY3w9Ur0XevnB9uJKv7nMaWCG46f//uT1P8

wD7eqv8hupJK+FnyzU5SzDyeO20ZzyN0e6M2GobhmmOmik3iB491+NskC5gBL2oB

kZBJROOrBtp9z27YXZTFjewgxzkUNzw+IVlsQD5h6XiyzOIfD2UtxvzxJs6qe3Kf

iAlqPfsETCBi6qxpnaBlUVQycfMCClbWzoI54dq3m9LgAeOJhljWnwSGnOGdLOGW

G+MDigPW5TYnD+JX4dRg4G3g/+Dm4VyV4DbihPWbZ+CA5IOlWefWOHpkJSOQi6JU

H1DgluHA9eAb4FjgYuGBaeCz5N8ur0undv+IiD08IJXlzgjiP74GiuGc2uFFgeFz

YOH3K+jHj0qPYhceyDp8mtmCgy7E/523HYsLgzu9nXbKajafo/6HRa2KLM1d0VGM

qZsEqF6Kr/1m1qBaV94oWju5z0f+bBtNCgXjbP2ibFAUlmuFvKsRHZVsdOo8BLkd

ed5Q9sw1fMXSzA6cxYClpeN6BmJ3KlLEkn6wxmbpUxR6VI17I2iZNA4rhzU2fYRR

egESqUF2tfZP5MDNUx8QzQdP6ch3okdKBg7hga59YA66QqbV2KczixWaFssWyqI+

AtInYYD/bHJQYHGdHgST3aLUO6wEALgpcK55AWHHjJAwoZUoVkEFN8KN6pAEutur

jRjTcfnkbCz4l/CxuN+jzLTevogM5NO+RU7ZKMkKVhzRoGM95lviTSwkj+E5mgA=

=wWmw

-----END PGP MESSAGE-----(09:26) jnml@fsc-r550:~/src/tmp/SO/17986762$