Signing Requests

sign_data = sorted_query_string + "\n" + body + "\n" + timestamp

package main

import (
    "crypto/ed25519"
    "encoding/base64"
    "fmt"
    "net/url"
    "sort"
    "strings"
    "time"
)

// buildSortedQueryString sorts query parameters by key.
func buildSortedQueryString(query url.Values) string {
    keys := make([]string, 0, len(query))
    for k := range query {
        keys = append(keys, k)
    }
    sort.Strings(keys)

    pairs := make([]string, 0, len(keys))
    for _, k := range keys {
        pairs = append(pairs, k+"="+query.Get(k))
    }
    return strings.Join(pairs, "&")
}

// signRequest signs the request using Ed25519.
// signData = sorted_query_string + "\n" + body + "\n" + timestamp
func signRequest(privateKeyB64 string, queryString string, body []byte) (signature string, timestamp string) {
    privateKey, _ := base64.StdEncoding.DecodeString(privateKeyB64)
    ts := fmt.Sprintf("%d", time.Now().Unix())
    signData := queryString + "\n" + string(body) + "\n" + ts
    sig := ed25519.Sign(ed25519.PrivateKey(privateKey), []byte(signData))
    return base64.StdEncoding.EncodeToString(sig), ts
}

func verifySignature(publicKeyB64 string, queryString string, body []byte, timestampStr string, signatureB64 string) bool {
    publicKey, _ := base64.StdEncoding.DecodeString(publicKeyB64)
    signData := queryString + "\n" + string(body) + "\n" + timestampStr
    signature, _ := base64.StdEncoding.DecodeString(signatureB64)
    return ed25519.Verify(ed25519.PublicKey(publicKey), []byte(signData), signature)
}