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ECKey: add BIP 137 support for signing text messages with segwit addresses

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BIP 137 defined new header byte values for the created signature
when the signature was created with a private key from a segwit
address.

This commit extends the "signMessage(..)" with a new ScriptType argument
(because the value of the signature header since BIP 137 depends on the
address type). This commit keeps the old methods (without the ScriptType
argument), but marks them as deprecated (using P2SH as default, if called
without ScriptType, thus not changing old behaviour).
This commit is contained in:
Johannes Zweng 2022-12-05 09:21:58 +01:00 • committed by Andreas Schildbach
parent e4f6dbd866
commit 070e53889e
1 changed files with 54 additions and 2 deletions
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56
core/src/main/java/org/bitcoinj/core/ECKey.java
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@ -777,9 +777,11 @@ public class ECKey implements EncryptableItem {
*
* @throws IllegalStateException if this ECKey does not have the private part.
* @throws KeyCrypterException if this ECKey is encrypted and no AESKey is provided or it does not decrypt the ECKey.
* @deprecated use {@link #signMessage(String, ScriptType)} instead and specify the correct script type
*/
@Deprecated
public String signMessage(String message) throws KeyCrypterException {
return signMessage(message, null);
return signMessage(message, null, ScriptType.P2PKH);
}
/**
@ -789,12 +791,62 @@ public class ECKey implements EncryptableItem {
* @throws IllegalStateException if this ECKey does not have the private part.
* @throws KeyCrypterException if this ECKey is encrypted and no AESKey is provided or it does not decrypt the ECKey.
*/
public String signMessage(String message, ScriptType scriptType) throws KeyCrypterException {
return signMessage(message, null, scriptType);
}
/**
* Signs a text message using the standard Bitcoin messaging signing format and returns the signature as a base64
* encoded string.
*
* @throws IllegalStateException if this ECKey does not have the private part.
* @throws KeyCrypterException if this ECKey is encrypted and no AESKey is provided or it does not decrypt the ECKey.
* @deprecated use {@link #signMessage(String, KeyParameter, ScriptType)} instead and specify the correct script type
*/
@Deprecated
public String signMessage(String message, @Nullable KeyParameter aesKey) throws KeyCrypterException {
return signMessage(message, aesKey, ScriptType.P2PKH);
}
/**
* Signs a text message using the standard Bitcoin messaging signing format and returns the signature as a base64
* encoded string.
*
* @throws IllegalArgumentException if uncompressed key is used for Segwit scriptType, or unsupported script type is specified
* @throws IllegalStateException if this ECKey does not have the private part.
* @throws KeyCrypterException if this ECKey is encrypted and no AESKey is provided or it does not decrypt the ECKey.
*/
public String signMessage(String message, @Nullable KeyParameter aesKey, ScriptType scriptType) throws KeyCrypterException {
if (!isCompressed() && (scriptType == ScriptType.P2WPKH || scriptType == ScriptType.P2SH)) {
throw new IllegalArgumentException("Segwit P2WPKH and P2SH-P2WPKH script types only can be used with compressed keys. See BIP 141.");
}
byte[] data = formatMessageForSigning(message);
Sha256Hash hash = Sha256Hash.twiceOf(data);
ECDSASignature sig = sign(hash, aesKey);
byte recId = findRecoveryId(hash, sig);
int headerByte = recId + 27 + (isCompressed() ? 4 : 0);
// Meaning of header byte ranges:
// * 27-30: P2PKH uncompressed, recId 0-3
// * 31-34: P2PKH compressed, recId 0-3
// * 35-38: Segwit P2SH (always compressed), recId 0-3
// * 39-42: Segwit Bech32 (always compressed), recId 0-3
// as defined in https://github.com/bitcoin/bips/blob/master/bip-0137.mediawiki#procedure-for-signingverifying-a-signature
int headerByte;
switch (scriptType) {
case P2PKH:
headerByte = recId + 27 + (isCompressed() ? 4 : 0);
break;
case P2SH: // P2SH-P2WPKH ("legacy-segwit")
headerByte = recId + 35;
break;
case P2WPKH:
headerByte = recId + 39;
break;
default:
throw new IllegalArgumentException("Unsupported script type for message signing.");
}
byte[] sigData = new byte[65]; // 1 header + 32 bytes for R + 32 bytes for S
sigData[0] = (byte)headerByte;
System.arraycopy(ByteUtils.bigIntegerToBytes(sig.r, 32), 0, sigData, 1, 32);