/**
* Create a clear sign signature over the input data. (Not detached)
*
* @param input the content to be signed
* @param keyring the keyring
* @param keyId the 4 bytes identifier of the key, in hexadecimal format
* @param passphrase the passphrase to retrieve the private key
* @param output the output destination of the signature
*/
public static void clearSign(
InputStream input, InputStream keyring, String keyId, String passphrase, OutputStream output)
throws IOException, PGPException, GeneralSecurityException {
PGPSecretKey secretKey = getSecretKey(keyring, keyId);
PGPPrivateKey privateKey =
secretKey.extractPrivateKey(
new BcPBESecretKeyDecryptorBuilder(new BcPGPDigestCalculatorProvider())
.build(passphrase.toCharArray()));
int digest = PGPUtil.SHA1;
PGPSignatureGenerator signatureGenerator =
new PGPSignatureGenerator(
new BcPGPContentSignerBuilder(secretKey.getPublicKey().getAlgorithm(), digest));
signatureGenerator.init(PGPSignature.CANONICAL_TEXT_DOCUMENT, privateKey);
ArmoredOutputStream armoredOutput = new ArmoredOutputStream(output);
armoredOutput.beginClearText(digest);
BufferedReader reader = new BufferedReader(new InputStreamReader(input));
String line;
while ((line = reader.readLine()) != null) {
// trailing spaces must be removed for signature calculation (see
// http://tools.ietf.org/html/rfc4880#section-7.1)
byte[] data = trim(line).getBytes("UTF-8");
armoredOutput.write(data);
armoredOutput.write(EOL);
signatureGenerator.update(data);
signatureGenerator.update(EOL);
}
armoredOutput.endClearText();
PGPSignature signature = signatureGenerator.generate();
signature.encode(new BCPGOutputStream(armoredOutput));
armoredOutput.close();
}
