feat: initial commit

main.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"encoding/pem"
+	"fmt"
+	"io"
+	"log"
+	"os"
+
+	"github.com/lestrrat-go/jwx/v2/jwk"
+)
+
+func main() {
+	// Read the JWK from standard input.
+	jwkBytes, err := io.ReadAll(os.Stdin)
+	if err != nil {
+		log.Fatalf("failed to read from stdin: %s", err)
+	}
+
+	// Parse the JWK.
+	key, err := jwk.ParseKey(jwkBytes)
+	if err != nil {
+		log.Fatalf("failed to parse JWK: %s", err)
+	}
+
+	// Get the public key.
+	var rawPublicKey interface{}
+	if err := key.Raw(&rawPublicKey); err != nil {
+		log.Fatalf("failed to get raw public key: %s", err)
+	}
+
+	// Encode the public key to PEM format. [4]
+	pemBytes, err := jwk.EncodePEM(key)
+	if err != nil {
+		log.Fatalf("failed to encode public key to PEM: %s", err)
+	}
+
+	// Write the PEM encoded public key to standard output.
+	block, _ := pem.Decode(pemBytes)
+	if block == nil {
+		log.Fatal("failed to decode PEM block")
+	}
+
+	if err := pem.Encode(os.Stdout, block); err != nil {
+		log.Fatalf("failed to write PEM block to stdout: %s", err)
+	}
+
+	fmt.Println()
+}