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Code Issues Releases Wiki Activity

Dedicated DKIM Ed25519

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M66B 2023-08-02 21:27:51 +02:00
parent ca0db4cbcc
commit 00d90ab07e
1 changed files with 32 additions and 19 deletions
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51
app/src/main/java/eu/faircode/email/MessageHelper.java
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@ -66,6 +66,8 @@ import org.apache.commons.compress.archivers.ArchiveInputStream;
import org.apache.commons.compress.archivers.ArchiveStreamFactory;
import org.apache.commons.compress.archivers.zip.UnsupportedZipFeatureException;
import org.apache.commons.compress.compressors.gzip.GzipCompressorInputStream;
import org.bouncycastle.crypto.params.Ed25519PublicKeyParameters;
import org.bouncycastle.crypto.signers.Ed25519Signer;
import org.json.JSONObject;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
@ -2453,35 +2455,46 @@ public class MessageHelper {
String p = pubkey.replaceAll("\\s+", "");
Log.i("DKIM pubkey=" + p);
X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(Base64.decode(p, Base64.DEFAULT));
KeyFactory keyFactory = KeyFactory.getInstance("Ed25519".equals(salgo) ? "Ed25519" : "RSA");
PublicKey pubKey = keyFactory.generatePublic(pubKeySpec);
Signature sig = Signature.getInstance(salgo); // a=
// https://stackoverflow.com/a/43984402/1794097
if (pubKey instanceof RSAPublicKey)
try {
int keylen = ((RSAPublicKey) pubKey).getModulus().bitLength();
Log.i("DKIM RSA pubkey length=" + keylen);
if (keylen < DKIM_MIN_KEY_LENGTH)
throw new IllegalArgumentException("RSA pubkey length " + keylen + " < " + DKIM_MIN_KEY_LENGTH);
} catch (Throwable ex) {
Log.e(ex);
}
String hash = kv.get("b");
if (hash == null)
return null;
String s = hash.replaceAll("\\s+", "");
Log.i("DKIM signature=" + s);
byte[] data = head.toString().getBytes();
byte[] key = Base64.decode(p, Base64.DEFAULT);
byte[] signature = Base64.decode(s, Base64.DEFAULT);
sig.initVerify(pubKey);
sig.update(head.toString().getBytes());
boolean verified;
if ("Ed25519".equals(salgo)) {
Ed25519Signer verifier = new Ed25519Signer();
verifier.init(false, new Ed25519PublicKeyParameters(key));
verifier.update(data, 0, data.length);
verified = verifier.verifySignature(signature);
} else {
X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(key);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey pubKey = keyFactory.generatePublic(pubKeySpec);
Signature sig = Signature.getInstance(salgo); // a=
// https://stackoverflow.com/a/43984402/1794097
if (pubKey instanceof RSAPublicKey)
try {
int keylen = ((RSAPublicKey) pubKey).getModulus().bitLength();
Log.i("DKIM RSA pubkey length=" + keylen);
if (keylen < DKIM_MIN_KEY_LENGTH)
throw new IllegalArgumentException("RSA pubkey length " + keylen + " < " + DKIM_MIN_KEY_LENGTH);
} catch (Throwable ex) {
Log.e(ex);
}
sig.initVerify(pubKey);
sig.update(data);
verified = sig.verify(signature);
}
boolean verified = sig.verify(signature);
Log.i("DKIM valid=" + verified +
" algo=" + salgo +
" dns=" + dns +
" from=" + formatAddresses(getFrom()));