ChaCha20#

Encrypt#

To test a function that encrypts with ChaCha20 only, its name must conform to the following convention:

CC_ChaCha20_encrypt

Its signature must be:

void CC_ChaCha20_encrypt(
uint8_t *buffer,
size_t buffer_size,
const uint8_t key[32],
const uint8_t *nonce,
size_t nonce_size,
uint64_t init_counter,
)#
Parameters:

  • buffer – [In/Out] A buffer containing the plaintext to encrypt, and to store the resulting ciphertext.

  • buffer_size – [In] The size of the buffer in bytes.

  • key – [In] The 32-byte symmetric key.

  • nonce – [In] The nonce.

  • nonce_size – [In] The size of the nonce in bytes.

  • init_counter – [In] An absolute position within the keystream in bytes to seek before encrypting.

Example:

void CC_ChaCha20_encrypt(uint8_t *buffer, size_t buffer_size,
                        const uint8_t key[32],
                        const uint8_t *nonce, size_t nonce_size,
                        uint64_t init_counter);

Decrypt#

To test a function that decrypts with ChaCha20 only, its name must conform to the following convention:

CC_ChaCha20_decrypt

Its signature must be:

void CC_ChaCha20_decrypt(
uint8_t *buffer,
size_t buffer_size,
const uint8_t key[32],
const uint8_t *nonce,
size_t nonce_size,
uint64_t init_counter,
)#
Parameters:

  • buffer – [In/Out] A buffer containing the ciphertext to decrypt, and to store the resulting plaintext.

  • buffer_size – [In] The size of the buffer in bytes.

  • key – [In] The 32-byte symmetric key.

  • nonce – [In] The nonce.

  • nonce_size – [In] The size of the nonce in bytes.

  • init_counter – [In] An absolute position within the keystream in bytes to seek before decrypting.

Example:

void CC_ChaCha20_encrypt(uint8_t *buffer, size_t buffer_size,
                        const uint8_t key[32],
                        const uint8_t *nonce, size_t nonce_size,
                        uint64_t init_counter);

Encrypt with Poly1305#

To test a function that encrypts with ChaCha20-Poly1305, its name must conform to the following convention:

CC_ChaCha20_Poly1305_encrypt

Its signature must be:

void CC_ChaCha20_Poly1305_encrypt(
uint8_t *buffer,
size_t buffer_size,
uint8_t mac[16],
const uint8_t key[32],
const uint8_t *nonce,
size_t nonce_size,
const uint8_t *aad,
size_t aad_size,
)#
Parameters:

  • buffer – [In/Out] A buffer containing the plaintext to encrypt, and to store the resulting ciphertext.

  • buffer_size – [In] The size of the buffer in bytes.

  • mac – [Out] A buffer to store the resulting 16-byte MAC tag.

  • key – [In] The 32-byte symmetric key.

  • nonce – [In] The nonce.

  • nonce_size – [In] The size of the nonce in bytes.

  • aad – [In] The optional associated data. NULL if not used.

  • aad_size – [In] The size of the associated data. 0 if not used.

Example:

void CC_ChaCha20_Poly1305_encrypt(uint8_t *buffer, size_t buffer_size,
                                 uint8_t mac[16],
                                 const uint8_t key[32],
                                 const uint8_t *nonce, size_t nonce_size,
                                 const uint8_t *aad, size_t aad_size);

Decrypt with Poly1305#

To test a function that decrypts with ChaCha20-Poly1305, its name must conform to the following convention:

CC_ChaCha20_Poly1305_decrypt

Its signature must be:

int CC_ChaCha20_Poly1305_decrypt(
uint8_t *buffer,
size_t buffer_size,
const uint8_t key[32],
const uint8_t *nonce,
size_t nonce_size,
const uint8_t *aad,
size_t aad_size,
const uint8_t mac[16],
)#
Parameters:

  • buffer – [In/Out] A buffer containing the ciphertext to decrypt, and to store the resulting plaintext. It is ignored if the function returns -2.

  • buffer_size – [In] The size of the buffer in bytes.

  • key – [In] The 32-byte symmetric key.

  • nonce – [In] The nonce.

  • nonce_size – [In] The size of the nonce in bytes.

  • aad – [In] The optional associated data. NULL if not used.

  • aad_size – [In] The size of the associated data. 0 if not used.

  • mac – [In] The 16-byte MAC tag to verify.

Returns:

A status value.

Return values:

  • 0 – OK.

  • -1 – The MAC verification failed.

Example:

int CC_ChaCha20_Poly1305_decrypt(uint8_t *buffer, size_t buffer_size,
                                 const uint8_t key[32],
                                 const uint8_t *nonce, size_t nonce_size,
                                 const uint8_t *aad, size_t aad_size,
                                 const uint8_t mac[16]);