gnutls_certificate_get_x509_crt - Linux


gnutls_certificate_get_x509_crt extracts the X.509 certificate from a GNUTLS certificate structure. It is useful for extracting certificates for further processing, verifying signatures, or analyzing certificate chains.


  • cert: The GNUTLS certificate structure containing the X.509 certificate.


This command does not support any options or flags.


Example 1: Extracting an X.509 certificate from a GNUTLS certificate structure:

# Load the GNUTLS certificate from a file
gnutls_certificate_load_file(cert, "cert.pem")

# Extract the X.509 certificate
x509_crt = gnutls_certificate_get_x509_crt(cert)

# Use the X.509 certificate for further processing...

Example 2: Verifying the signature of a certificate using the extracted X.509 certificate:

# Extract the X.509 certificate
x509_crt = gnutls_certificate_get_x509_crt(cert)

# Get the issuer certificate
issuer_x509_crt = gnutls_x509_crt_get_issuer_cert(x509_crt)

# Verify the signature of the certificate using the issuer's public key
result = gnutls_x509_crt_verify_signature(x509_crt, issuer_x509_crt)

Common Issues

  • Error handling: If gnutls_certificate_load_file fails to load the certificate or if the provided GNUTLS certificate structure is invalid, the function will return GNUTLS_E_INVALID_CERTIFICATE.
  • Incorrect format: Ensure that the provided certificate is in X.509 format, as other formats are not supported by this function.


gnutls_certificate_get_x509_crt can be combined with other GNUTLS functions to perform complex tasks related to certificate management and verification. For instance, it can be used in conjunction with gnutls_x509_crt_get_issuer_cert to retrieve the issuer certificate of a given certificate, enabling certificate chain validation.

Related Commands

  • gnutls_certificate_get_dn: Get the distinguished name of a certificate.
  • gnutls_certificate_get_key: Get the public key of a certificate.
  • gnutls_x509_crt_verify_signature: Verify the signature of a certificate.