gnutls_cipher_encrypt3 - Linux


gnutls_cipher_encrypt3 is a function in the GnuTLS library specifically designed to encrypt data using a specified cipher and a given key in the third iteration. This command is commonly used in cryptographic operations, such as securing communication channels or protecting sensitive data.


int gnutls_cipher_encrypt3(const gnutls_cipher_algorithm_t *cipher,
                            const unsigned char *iv,
                            const unsigned char *key,
                            const unsigned char *plaintext,
                            size_t plaintext_length,
                            unsigned char *ciphertext,
                            size_t ciphertext_length);




// Encrypt a message using AES-256 with a given key and IV
unsigned char plaintext[] = "Top Secret!";
unsigned char key[] = "..." // Replace with your actual key
unsigned char iv[] = "..." // Replace with your actual IV
unsigned char ciphertext[256]; // Buffer for encrypted message

// Encrypt the plaintext
gnutls_cipher_encrypt3(GNUTLS_CIPHER_AES_256, iv, key,
                    plaintext, strlen(plaintext), ciphertext, sizeof(ciphertext));

// Print out the encrypted ciphertext
printf("Encrypted ciphertext: ");
for (size_t i = 0; i < strlen(plaintext); i++) {
    printf("%02X", ciphertext[i]);

Common Issues

  • Invalid key size: Ensure that the provided key is the correct size for the specified cipher.
  • Invalid IV size: The IV (initialization vector) size must match the block size of the cipher.
  • Buffer overflow: The ciphertext buffer must be large enough to accommodate the encrypted message.


gnutls_cipher_encrypt3 can be integrated with other GnuTLS functions to create more complex cryptographic operations. For example, it can be combined with gnutls_cipher_decrypt3 for decryption or gnutls_cipher_init to initialize a cipher structure.

Related Commands

  • gnutls_cipher_decrypt3
  • gnutls_cipher_init
  • gnutls_certificate_verify