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Sanitise and UTF-8 url decode cert before base64 decoding #2438

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merged 2 commits into from
Apr 29, 2024
Merged

Sanitise and UTF-8 url decode cert before base64 decoding #2438

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dd8ba85
Sanitize and url decode cert before base64 decoding
anjuchamantha Apr 26, 2024
15b4763
Remove unnecessary debug log
anjuchamantha Apr 29, 2024
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49 changes: 41 additions & 8 deletions ...java/org/wso2/carbon/identity/oauth2/token/bindings/impl/CertificateBasedTokenBinder.java
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Original file line number Diff line number Diff line change
Expand Up @@ -36,10 +36,14 @@
import org.wso2.carbon.identity.openidconnect.model.Constants;

import java.io.ByteArrayInputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.nio.charset.StandardCharsets;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.Arrays;
import java.util.Base64;
import java.util.List;
import java.util.Optional;
import java.util.Set;
Expand Down Expand Up @@ -162,7 +166,7 @@ private String generateCnfHashValue(HttpServletRequest request) {
if (StringUtils.isNotBlank(certificateInHeader)) {
try {
certificate = parseCertificate(certificateInHeader);
} catch (CertificateException e) {
} catch (CertificateException | UnsupportedEncodingException e) {
/* Adding a debug log as these errors cannot be thrown as per the TokenBinder interface implementation.
But null checks have been performed where these methods are being executed. */
if (log.isDebugEnabled()) {
Expand All @@ -188,14 +192,43 @@ private String generateCnfHashValue(HttpServletRequest request) {
}
}

private X509Certificate parseCertificate(String content) throws CertificateException {
/**
* Return Certificate for give Certificate Content.
*
* @param content Certificate Content
* @return X509Certificate X.509 certificate after decoding the certificate content.
* @throws CertificateException Certificate Exception.
*/
private X509Certificate parseCertificate(String content) throws CertificateException, UnsupportedEncodingException {

byte[] decoded;
String sanitizedCertificate = sanitizeCertificate(content);
// First we try to Base64 decode, if it is not decodable, we try to url decode first and then Base64 decode.
try {
decoded = Base64.getDecoder().decode(sanitizedCertificate);
} catch (IllegalArgumentException e) {
log.debug("Error while base64 decoding the certificate. Trying URL decoding first.");
String urlDecodedContent = URLDecoder.decode(content, StandardCharsets.UTF_8.name());
sanitizedCertificate = sanitizeCertificate(urlDecodedContent);
decoded = Base64.getDecoder().decode(sanitizedCertificate);
}

byte[] decodedContent = java.util.Base64.getDecoder().decode(StringUtils.trim(content
.replaceAll(OAuthConstants.BEGIN_CERT, StringUtils.EMPTY)
.replaceAll(OAuthConstants.END_CERT, StringUtils.EMPTY)
));
return (java.security.cert.X509Certificate) CertificateFactory.getInstance(Constants.X509)
.generateCertificate(new ByteArrayInputStream(decoded));
}

return (X509Certificate) CertificateFactory.getInstance(Constants.X509)
.generateCertificate(new ByteArrayInputStream(decodedContent));
/**
* Sanitize the certificate before decoding.
* @param content certificate as a string.
* @return sanitized certificate.
*/
private String sanitizeCertificate(String content) {

String certContent = StringUtils.trim(content);
// Remove Certificate Headers.
String certBody = certContent.replaceAll(OAuthConstants.BEGIN_CERT, StringUtils.EMPTY)
.replaceAll(OAuthConstants.END_CERT, StringUtils.EMPTY);
// Removing all whitespaces and new lines.
return certBody.replaceAll("\\s", StringUtils.EMPTY).replace("\\n", StringUtils.EMPTY);
}
}