EVP_chacha20.3ssl - Man Page

EVP ChaCha20 stream cipher


 #include <openssl/evp.h>

 const EVP_CIPHER *EVP_chacha20(void)
 const EVP_CIPHER *EVP_chacha20_poly1305(void)


The ChaCha20 stream cipher for EVP.


The ChaCha20 stream cipher. The key length is 256 bits, the IV is 128 bits long. The first 32 bits consists of a counter in little-endian order followed by a 96 bit nonce. For example a nonce of:


With an initial counter of 42 (2a in hex) would be expressed as:



Authenticated encryption with ChaCha20-Poly1305. Like EVP_chacha20(), the key is 256 bits and the IV is 96 bits. This supports additional authenticated data (AAD) and produces a 128-bit authentication tag. See the “AEAD Interface” in EVP_EncryptInit(3) section for more information.

Return Values

These functions return an EVP_CIPHER structure that contains the implementation of the symmetric cipher. See EVP_CIPHER_meth_new(3) for details of the EVP_CIPHER structure.

See Also

evp(7), EVP_EncryptInit(3), EVP_CIPHER_meth_new(3)

Referenced By


The man page EVP_chacha20_poly1305.3ssl(3) is an alias of EVP_chacha20.3ssl(3).

2021-02-10 1.1.1i OpenSSL