CAPLfunctionX509Decoder DecodeCertificate

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X509Decoder_DecodeCertificate

CAPL Functions » Security » X509Decoder_DecodeCertificate

Tool Availability

Valid for: CANoe DE • CANoe4SW DE

Method Syntax

dword X509Decoder_DecodeCertificate(qword objectHandle, qword& outHandleCertificate, byte[] certificateData, dword certificateDataLength)

Description

Decoding function for an X.509 Certificate from binary data in DER or PEM format. Function will fail in case of invalid encoded data or invalid ASN.1 or X.509 Certificate structure.

Parameters

• objectHandle: (in) Handle with type ‘X509Decoder’. The function will be called in context of this handle.

Return Values

• 1: NoError: Operation was completed successfully.
• -2: Nullpointer: Error, the return value of the function was “NULL”. The value is not available and the output buffer is unchanged.
• -3: BufferTooSmall: Error, the output buffer is too small. No value has been written.
• -4: InvalidHandle: Error, the provided objectHandle is invalid or not suitable for this function.
• -5: InvalidArgument: Error, one or more arguments are invalid for this function.
• -6: InvalidArgumentHandle: Error, one or more argument handles are invalid or not suitable for this function.

Example

variables
{
  qword objectFactory;
  // Object handles
  qword pkiAccess, decoder, encoder, verifier, signer, rootCert, ecuCert, subject;
  // Result of certificate chain verification
  dword verificationResult;

  // Buffers
  byte keyBuffer[1000];
  byte byteBuffer[1000];
  char strBuffer[1000];
  dword keyBufferLen;
  dword byteBufferLen;
  dword strBufferLen;
}

void X509_Modify_Sign_And_Verify() {

  // X509 Object factory is the entry point for X.509 features. It is used to create object handles
  objectFactory = GetX509ObjectFactory();
  // Create handles for PkiAccess, Decoder, Encoder, Verifier
  X509ObjectFactory_createX509Decoder(objectFactory, decoder);
  X509ObjectFactory_createX509Encoder(objectFactory, encoder);
  X509ObjectFactory_createX509Verifier(objectFactory, verifier);
  X509ObjectFactory_createX509PkiAccess(objectFactory, pkiAccess);

  // Note: This sample code does not contain the required crypto material.
  // The required format is DER encoded X.509 certificate / private key as hexadecimal string, e.g. 112233AABBDD
  // Please use your existing (hex encoded) key and certificates or use an example value included in Security Manager Configurator

  // Decode the binary root certificate, lead certificate and root private key.
  keyBufferLen = 1000;
  X509ObjectFactory_BytesFromHexString(objectFactory, " *** YOUR HEX ENCODED SIGNER PRIVATE KEY *** ", keyBuffer, keyBufferLen);

  byteBufferLen = 1000;
  X509ObjectFactory_BytesFromHexString(objectFactory, " *** YOUR HEX ENCODED ECU CERTIFICATE *** ", byteBuffer, byteBufferLen);
  X509Decoder_DecodeCertificate(decoder, ecuCert, byteBuffer, byteBufferLen);

  byteBufferLen = 1000;
  X509ObjectFactory_BytesFromHexString(objectFactory, " *** YOUR HEX ENCODED SIGNER CERTIFICATE *** ", byteBuffer, byteBufferLen);
  X509PkiAccess_CreateSigner(pkiAccess, keyBuffer, keyBufferLen, byteBuffer, byteBufferLen, "SHA-256", signer);

  // Load the signer certificate handle
  X509Signer_GetSignerCertificate(signer, rootCert);

  // Now add the root certificates to the truststore of the verifier. These will be used for chain verification
  X509Verifier_AddTrustedCertificate(verifier, rootCert);

  // Verify the certificate against the truststore -> It is unchanged and must be valid
  verificationResult = 0;
  X509Verifier_VerifyCertificateChain(verifier, ecuCert, verificationResult);
  write("Verification result: %d", verificationResult);

  // Update the root certificates validity dates
  X509Certificate_SetValidFrom(rootCert, "20000101000000Z");
  X509Certificate_SetValidTo(rootCert, "20300101000000Z");
  X509Signer_UpdateAndSignCertificate(signer, rootCert);

  // Verify the certificate against the truststore -> Root certificate is re-signed and must be valid
  verificationResult = 0;
  X509Verifier_VerifyCertificateChain(verifier, ecuCert, verificationResult);
  write("Verification result: %d", verificationResult);

  // Get the subject DN from the certificate
  X509Certificate_GetSubjectDN(ecuCert, subject);

  // Update the ecu certificates validity dates
  X509Certificate_SetValidFrom(ecuCert, "20000101000000Z");
  X509Certificate_SetValidTo(ecuCert, "20300101000000Z");
  X509DN_SetValueForAttribute(subject, "2.5.4.3", "TESTTEST"); // Update CN
  X509DN_SetValueForAttribute(subject, "1.2.3.4", "ANOTHER_TESTTEST"); // Add custom Attribute

  // Now update the signature and all relevant fields (Issuer, Auth Key Identifier, SignatureAlgorithm)
  X509Signer_UpdateAndSignCertificate(signer, ecuCert);

  // Again verify the certificate against the truststore -> It received a fresh signature and must be invalid
  verificationResult = 0;
  X509Verifier_VerifyCertificateChain(verifier, ecuCert, verificationResult);
  write("Verification result: %d", verificationResult);

  // Utility to print the byte buffer into a hex string for printing
  write("Generated certificates:");
  write("Root:");
  byteBufferLen = 1000;
  X509Encoder_EncodeCertificate(encoder, rootCert, byteBuffer, byteBufferLen); // (DER-) encode the certificate structure into a byte buffer
  strBufferLen = 1000;
  X509ObjectFactory_BytesToHexString(objectFactory, byteBuffer, byteBufferLen, strBuffer, strBufferLen);
  write("Hex:\n%s", strBuffer);
  strBufferLen = 1000;
  X509Certificate_ToString(rootCert, strBuffer, strBufferLen);
  write("Textual:\n%s", strBuffer);
  write("Child:");
  byteBufferLen = 1000;
  X509Encoder_EncodeCertificate(encoder, ecuCert, byteBuffer, byteBufferLen); // (DER-) encode the certificate structure into a byte buffer
  strBufferLen = 1000;
  X509ObjectFactory_BytesToHexString(objectFactory, byteBuffer, byteBufferLen, strBuffer, strBufferLen);
  write("Hex:\n%s", strBuffer);
  strBufferLen = 1000;
  X509Certificate_ToString(ecuCert, strBuffer, strBufferLen);
  write("Textual:\n%s", strBuffer);
}