Add metadata attribute parsing cli tool

attributes.go

@@ -214,6 +214,10 @@ func (attr *MetadataAttribute) setCredentialTypeIdentifier(id string) {
 	attr.setField(credentialID, bytes[:16])
 }
 
+func (attr *MetadataAttribute) CredentialTypeHash() []byte {
+	return attr.field(credentialID)
+}
+
 // Expiry returns the expiry date of this instance
 func (attr *MetadataAttribute) Expiry() time.Time {
 	expiry := attr.SigningDate().Unix() + int64(attr.ValidityDuration()*ExpiryFactor)

irmameta/irmameta.go

+package main
+
+import (
+	"encoding/base64"
+	"fmt"
+	"math/big"
+	"os"
+	"time"
+
+	"encoding/json"
+
+	"github.com/credentials/irmago"
+	"github.com/mhe/gabi"
+)
+
+func main() {
+	if len(os.Args) != 3 {
+		fmt.Println("Usage: irmago metadata_attribute_in_decimal path_to_irma_configuration")
+	}
+
+	metaint, ok := new(big.Int).SetString(os.Args[1], 10)
+	if !ok {
+		fmt.Println("Could not parse argument as decimal integer:")
+		os.Exit(1)
+	}
+
+	confpath := os.Args[2]
+	conf, err := irma.NewConfiguration(confpath, "")
+	if err != nil {
+		fmt.Println("Failed to parse irma_configuration:", err)
+		os.Exit(1)
+	}
+	err = conf.ParseFolder()
+	if err != nil {
+		fmt.Println("Failed to parse irma_configuration:", err)
+		os.Exit(1)
+	}
+
+	meta := irma.MetadataFromInt(metaint, conf)
+	typ := meta.CredentialType()
+	var key *gabi.PublicKey
+
+	if typ == nil {
+		fmt.Println("Unknown credential type, hash:", base64.StdEncoding.EncodeToString(meta.CredentialTypeHash()))
+	} else {
+		fmt.Println("Identifier      :", typ.Identifier())
+		key, err = meta.PublicKey()
+		if err != nil {
+			fmt.Println("Failed to parse public key", err)
+		}
+	}
+	fmt.Println("Signed          :", meta.SigningDate().String())
+	fmt.Println("Expires         :", meta.Expiry().String())
+	fmt.Println("IsValid()       :", meta.IsValid())
+	fmt.Println("KeyCounter      :", meta.KeyCounter())
+	if key != nil {
+		fmt.Println("KeyExpires      :", time.Unix(key.ExpiryDate, 0))
+		fmt.Println("KeyModulusBitlen:", key.N.BitLen())
+	}
+
+	fmt.Println()
+	fmt.Println("CredentialType  :", prettyprint(typ))
+}
+
+func prettyprint(ob interface{}) string {
+	b, err := json.MarshalIndent(ob, "", "  ")
+	if err != nil {
+		fmt.Println("error:", err)
+	}
+	return string(b)
+}