Function group_cipher_decrypt 

pub unsafe extern "C" fn group_cipher_decrypt(
    cipher: *mut group_cipher,
    ciphertext: *mut sender_key_message,
    decrypt_context: *mut c_void,
    plaintext: *mut *mut signal_buffer,
) -> c_int

Decrypt a message.

@param ciphertext The sender_key_message to decrypt. @param decrypt_context Optional context pointer associated with the ciphertext, which is passed to the decryption callback function @param plaintext Set to a newly allocated buffer containing the plaintext.

@retval SG_SUCCESS Success @retval SG_ERR_INVALID_MESSAGE if the input is not valid ciphertext. @retval SG_ERR_DUPLICATE_MESSAGE if the input is a message that has already been received. @retval SG_ERR_LEGACY_MESSAGE if the input is a message formatted by a protocol version that is no longer supported. @retval SG_ERR_NO_SESSION if there is no established session for this contact.