Print checksums of certificates public key, entire certificate, subject field, issuer field

print-certs.go

package main

import "crypto/sha1"
import "crypto/x509"
import "fmt"
import "encoding/pem"
import "os"
import "time"
import "bufio"
import "strings"


func handleCert(pemdata []byte) {
    asn1block, _ := pem.Decode(pemdata)
    if asn1block == nil {
        fmt.Fprintln(os.Stderr, "no valid pem data found")
        return
    }
    cert, err := x509.ParseCertificate(asn1block.Bytes)
    if err != nil {
        fmt.Fprintln(os.Stderr, err)
    } else {
        hash := sha1.New()
        hash.Write(cert.Raw)
        pkeyhash := sha1.New()
        pkeyhash.Write(cert.RawSubjectPublicKeyInfo)
        subjecth := sha1.New()
        subjecth.Write(cert.RawSubject)
        issuerh := sha1.New()
        issuerh.Write(cert.RawIssuer)

        fmt.Println(fmt.Sprintf("%X %X %X %X", pkeyhash.Sum(nil), hash.Sum(nil), subjecth.Sum(nil), issuerh.Sum(nil)))
    }
}


func handleCerts(queue chan []byte) {
    for {
        handleCert(<-queue)
    }
}


func main () {
    cs := make(chan []byte)
    for i := 0; i < 3; i++ {
        go handleCerts(cs)
    }
    scanner := bufio.NewScanner(os.Stdin)
    fragment := ""
    for scanner.Scan() {
        line := scanner.Text()
        fragment = fragment + "\n" + line
        if strings.Contains(line, "END CERTIFICATE") {
            cs <- []byte(fragment)
            fragment = ""
        }
    }
    time.Sleep(2 * time.Second)
}