Botan::ChaCha Class Reference

#include <chacha.h>

Inheritance diagram for Botan::ChaCha:

Public Member Functions
size_t	buffer_size () const override
	ChaCha (size_t rounds=20)
void	cipher (const uint8_t in[], uint8_t out[], size_t len)
void	cipher (std::span< const uint8_t > in, std::span< uint8_t > out)
void	cipher1 (std::span< uint8_t > buf)
void	cipher1 (uint8_t buf[], size_t len)
void	clear () override
StreamCipher *	clone () const
void	decrypt (std::span< uint8_t > inout)
size_t	default_iv_length () const override
void	encipher (std::span< uint8_t > inout)
void	encrypt (std::span< uint8_t > inout)
bool	has_keying_material () const override
Key_Length_Specification	key_spec () const override
template<concepts::resizable_byte_buffer T = secure_vector<uint8_t>>
T	keystream_bytes (size_t bytes)
size_t	maximum_keylength () const
size_t	minimum_keylength () const
std::string	name () const override
std::unique_ptr< StreamCipher >	new_object () const override
std::string	provider () const override
std::optional< uint64_t >	remaining_keystream_bytes () const override
void	seek (uint64_t offset) override
void	set_iv (const uint8_t iv[], size_t iv_len)
void	set_iv (std::span< const uint8_t > iv)
void	set_key (const OctetString &key)
void	set_key (const uint8_t key[], size_t length)
void	set_key (std::span< const uint8_t > key)
bool	supports_seek () const override
bool	valid_iv_length (size_t iv_len) const override
bool	valid_keylength (size_t length) const
void	write_keystream (std::span< uint8_t > out)
void	write_keystream (uint8_t out[], size_t len)

Static Public Member Functions
static std::unique_ptr< StreamCipher >	create (std::string_view algo_spec, std::string_view provider="")
static std::unique_ptr< StreamCipher >	create_or_throw (std::string_view algo_spec, std::string_view provider="")
static std::vector< std::string >	providers (std::string_view algo_spec)

Protected Member Functions
void	assert_key_material_set () const
void	assert_key_material_set (bool predicate) const

Detailed Description

DJB's ChaCha (https://cr.yp.to/chacha.html)

Definition at line 18 of file chacha.h.

Constructor & Destructor Documentation

ChaCha()

Botan::ChaCha::ChaCha ( size_t rounds = 20 )

explicit

Parameters

rounds

number of rounds

Note

Currently only 8, 12 or 20 rounds are supported, all others will throw an exception

Definition at line 92 of file chacha.cpp.

                            : m_rounds(rounds) {
   BOTAN_ARG_CHECK(m_rounds == 8 || m_rounds == 12 || m_rounds == 20, "ChaCha only supports 8, 12 or 20 rounds");
}

References BOTAN_ARG_CHECK.

Member Function Documentation

assert_key_material_set() [1/2]

void Botan::SymmetricAlgorithm::assert_key_material_set ( ) const

inlineprotectedinherited

Throw Key_Not_Set unless a key has been set on this object

Definition at line 180 of file sym_algo.h.

{ assert_key_material_set(has_keying_material()); }

References assert_key_material_set(), and has_keying_material().

Referenced by assert_key_material_set(), Botan::Salsa20::cipher_bytes(), Botan::Lion::decrypt_n(), Botan::Lion::encrypt_n(), Botan::GHASH::final(), Botan::Polyval::final(), Botan::Salsa20::generate_keystream(), Botan::GHASH::nonce_hash(), Botan::GHASH::reset_associated_data(), Botan::ChaCha::seek(), Botan::CTR_BE::seek(), Botan::Salsa20::seek(), Botan::GHASH::set_associated_data(), Botan::OCB_Mode::set_associated_data_n(), Botan::Salsa20::set_iv_bytes(), Botan::GHASH::update(), Botan::Polyval::update(), Botan::GHASH::update_associated_data(), and Botan::Polyval::zero_pad().

assert_key_material_set() [2/2]

void Botan::SymmetricAlgorithm::assert_key_material_set ( bool predicate ) const

inlineprotectedinherited

Throw Key_Not_Set unless the predicate holds

Parameters

predicate

if false, a Key_Not_Set exception is thrown

Definition at line 186 of file sym_algo.h.

                                                         {
         if(!predicate) {
            throw_key_not_set_error();
         }
      }

buffer_size()

size_t Botan::ChaCha::buffer_size ( ) const

overridevirtual

Return the optimium buffer size to use with this cipher

Most stream ciphers internally produce blocks of bytes. This function returns that block size. Aligning buffer sizes to a multiple of this size may improve performance by reducing internal buffering overhead.

Note the return value of this function may change for any particular algorithm due to changes in the implementation from release to release, or changes in the runtime environment (such as CPUID indicating availability of an optimized implementation). It is not intrinsic to the algorithm; it is just a suggestion for gaining best performance.

Implements Botan::StreamCipher.

Definition at line 341 of file chacha.cpp.

                                 {
   return 64;
}

cipher() [1/2]

void Botan::StreamCipher::cipher ( const uint8_t in[], uint8_t out[], size_t len )

inlineinherited

Encrypt or decrypt a message

Processes all bytes plain/ciphertext from in and writes the result to out.

Parameters

in	the plaintext
out	the byte array to hold the output, i.e. the ciphertext
len	the length of both in and out in bytes

Definition at line 61 of file stream_cipher.h.

{ cipher_bytes(in, out, len); }

References cipher_bytes().

Referenced by cipher1(), cipher1(), create(), Botan::Sodium::crypto_stream_salsa20_xor_ic(), Botan::Sodium::crypto_stream_xsalsa20_xor_ic(), Botan::CTR_BE::CTR_BE(), Botan::CTR_BE::CTR_BE(), decrypt(), encipher(), encrypt(), and Botan::OFB::OFB().

cipher() [2/2]

void Botan::StreamCipher::cipher ( std::span< const uint8_t > in, std::span< uint8_t > out )

inherited

Encrypt or decrypt a message

Parameters

in	the plaintext
out	the byte array to hold the output, i.e. the ciphertext with at least the same size as in

Definition at line 133 of file stream_cipher.cpp.

                                                                         {
   BOTAN_ARG_CHECK(in.size() <= out.size(), "Output buffer of stream cipher must be at least as long as input buffer");
   cipher_bytes(in.data(), out.data(), in.size());
}

References BOTAN_ARG_CHECK, and cipher_bytes().

cipher1() [1/2]

void Botan::StreamCipher::cipher1 ( std::span< uint8_t > buf )

inlineinherited

Encrypt or decrypt a message The message is encrypted/decrypted in place.

Parameters

buf	the plaintext / ciphertext

Definition at line 117 of file stream_cipher.h.

{ cipher(buf, buf); }

References cipher().

cipher1() [2/2]

void Botan::StreamCipher::cipher1 ( uint8_t buf[], size_t len )

inlineinherited

Encrypt or decrypt a message The message is encrypted/decrypted in place.

Parameters

buf	the plaintext / ciphertext
len	the length of buf in bytes

Definition at line 110 of file stream_cipher.h.

{ cipher(buf, buf, len); }

References cipher().

Referenced by generate_keystream().

clear()

void Botan::ChaCha::clear ( )

overridevirtual

Reset the internal state. This includes not just the key, but any partial message that may have been in process.

Implements Botan::SymmetricAlgorithm.

Definition at line 429 of file chacha.cpp.

                   {
   zap(m_key);
   zap(m_state);
   zap(m_buffer);
   m_position = 0;
   m_iv_length = 0;
   m_state13_post_iv = 0;
   m_bytes_remaining = 0;
}

References Botan::zap().

clone()

StreamCipher * Botan::StreamCipher::clone ( ) const

inlineinherited

Create a new uninitialized object of the same type

Returns

a new object representing the same algorithm as *this

Definition at line 198 of file stream_cipher.h.

{ return this->new_object().release(); }

References new_object().

create()

std::unique_ptr< StreamCipher > Botan::StreamCipher::create ( std::string_view algo_spec, std::string_view provider = "" )

staticinherited

Create an instance based on a name If provider is empty then best available is chosen.

Parameters

algo_spec	algorithm name
provider	provider implementation to use

Returns

a null pointer if the algo/provider combination cannot be found

Definition at line 40 of file stream_cipher.cpp.

                                                                                                  {
#if defined(BOTAN_HAS_SHAKE_CIPHER)
   if(algo_spec == "SHAKE-128" || algo_spec == "SHAKE-128-XOF") {
      if(provider.empty() || provider == "base") {
         return std::make_unique<SHAKE_128_Cipher>();
      }
   }
 
   if(algo_spec == "SHAKE-256" || algo_spec == "SHAKE-256-XOF") {
      if(provider.empty() || provider == "base") {
         return std::make_unique<SHAKE_256_Cipher>();
      }
   }
#endif
 
#if defined(BOTAN_HAS_CHACHA)
   if(algo_spec == "ChaCha20") {
      if(provider.empty() || provider == "base") {
         return std::make_unique<ChaCha>(20);
      }
   }
#endif
 
#if defined(BOTAN_HAS_SALSA20)
   if(algo_spec == "Salsa20") {
      if(provider.empty() || provider == "base") {
         return std::make_unique<Salsa20>();
      }
   }
#endif
 
   const SCAN_Name req(algo_spec);
 
#if defined(BOTAN_HAS_CTR_BE)
   if((req.algo_name() == "CTR-BE" || req.algo_name() == "CTR") && req.arg_count_between(1, 2)) {
      if(provider.empty() || provider == "base") {
         auto cipher = BlockCipher::create(req.arg(0));
         if(cipher) {
            const size_t ctr_size = req.arg_as_integer(1, cipher->block_size());
            return std::make_unique<CTR_BE>(std::move(cipher), ctr_size);
         }
      }
   }
#endif
 
#if defined(BOTAN_HAS_CHACHA)
   if(req.algo_name() == "ChaCha") {
      if(provider.empty() || provider == "base") {
         return std::make_unique<ChaCha>(req.arg_as_integer(0, 20));
      }
   }
#endif
 
#if defined(BOTAN_HAS_OFB)
   if(req.algo_name() == "OFB" && req.arg_count() == 1) {
      if(provider.empty() || provider == "base") {
         if(auto cipher = BlockCipher::create(req.arg(0))) {
            return std::make_unique<OFB>(std::move(cipher));
         }
      }
   }
#endif
 
#if defined(BOTAN_HAS_RC4)
 
   if(req.algo_name() == "RC4" || req.algo_name() == "ARC4" || req.algo_name() == "MARK-4") {
      const size_t skip = (req.algo_name() == "MARK-4") ? 256 : req.arg_as_integer(0, 0);
 
      if(provider.empty() || provider == "base") {
         return std::make_unique<RC4>(skip);
      }
   }
 
#endif
 
   BOTAN_UNUSED(req);
   BOTAN_UNUSED(provider);
 
   return nullptr;
}

References Botan::SCAN_Name::algo_name(), Botan::SCAN_Name::arg(), Botan::SCAN_Name::arg_as_integer(), Botan::SCAN_Name::arg_count(), Botan::SCAN_Name::arg_count_between(), BOTAN_UNUSED, cipher(), Botan::BlockCipher::create(), and provider().

Referenced by Botan::BlockCipher::create(), Botan::Cipher_Mode::create(), and create_or_throw().

create_or_throw()

std::unique_ptr< StreamCipher > Botan::StreamCipher::create_or_throw ( std::string_view algo_spec, std::string_view provider = "" )

staticinherited

Create an instance based on a name If provider is empty then best available is chosen.

Parameters

algo_spec	algorithm name
provider	provider implementation to use Throws a Lookup_Error if the algo/provider combination cannot be found

Definition at line 122 of file stream_cipher.cpp.

                                                                                                      {
   if(auto sc = StreamCipher::create(algo, provider)) {
      return sc;
   }
   throw Lookup_Error("Stream cipher", algo, provider);
}

References create(), and provider().

Referenced by Botan::ChaCha_RNG::ChaCha_RNG(), Botan::ChaCha_RNG::ChaCha_RNG(), Botan::ChaCha_RNG::ChaCha_RNG(), Botan::ChaCha_RNG::ChaCha_RNG(), Botan::ChaCha_RNG::ChaCha_RNG(), Botan::Sodium::crypto_secretbox_detached(), Botan::Sodium::crypto_secretbox_open_detached(), Botan::Sodium::crypto_secretbox_xsalsa20poly1305(), Botan::Sodium::crypto_secretbox_xsalsa20poly1305_open(), Botan::Sodium::crypto_stream_chacha20(), Botan::Sodium::crypto_stream_chacha20_ietf(), Botan::Sodium::crypto_stream_chacha20_ietf_xor_ic(), Botan::Sodium::crypto_stream_chacha20_xor_ic(), Botan::Sodium::crypto_stream_xchacha20(), and Botan::Sodium::crypto_stream_xchacha20_xor_ic().

decrypt()

void Botan::StreamCipher::decrypt ( std::span< uint8_t > inout )

inlineinherited

Decrypt a message in place The message is decrypted in place.

Parameters

inout

the plaintext / ciphertext

Definition at line 138 of file stream_cipher.h.

{ cipher(inout.data(), inout.data(), inout.size()); }

References cipher().

default_iv_length()

size_t Botan::ChaCha::default_iv_length ( ) const

overridevirtual

Return the default (preferred) nonce length

If this function returns zero, then this cipher does not support nonces; in this case any call to set_iv with a (non-empty) value will fail.

Default implementation returns 0

Reimplemented from Botan::StreamCipher.

Definition at line 360 of file chacha.cpp.

                                       {
   return 24;
}

encipher()

void Botan::StreamCipher::encipher ( std::span< uint8_t > inout )

inlineinherited

Encrypt a message The message is encrypted/decrypted in place.

Parameters

inout

the plaintext / ciphertext

Definition at line 124 of file stream_cipher.h.

{ cipher(inout.data(), inout.data(), inout.size()); }

References cipher().

encrypt()

void Botan::StreamCipher::encrypt ( std::span< uint8_t > inout )

inlineinherited

Encrypt a message The message is encrypted in place.

Parameters

inout

the plaintext / ciphertext

Definition at line 131 of file stream_cipher.h.

{ cipher(inout.data(), inout.data(), inout.size()); }

References cipher().

has_keying_material()

bool Botan::ChaCha::has_keying_material ( ) const

overridevirtual

Test whether a key has been set on this object

Returns

true if a key has been set on this object

Implements Botan::SymmetricAlgorithm.

Definition at line 337 of file chacha.cpp.

                                       {
   return !m_state.empty();
}

Referenced by remaining_keystream_bytes().

key_spec()

Key_Length_Specification Botan::ChaCha::key_spec ( ) const

overridevirtual

Return the key lengths supported by this algorithm

Returns

object describing limits on key size

Implements Botan::SymmetricAlgorithm.

Definition at line 364 of file chacha.cpp.

                                                {
   return Key_Length_Specification(16, 32, 16);
}

keystream_bytes()

template<concepts::resizable_byte_buffer T = secure_vector<uint8_t>>

T Botan::StreamCipher::keystream_bytes ( size_t bytes )

inlineinherited

Get bytes from the keystream

The bytes are written into a continuous byte buffer of your choosing.

Parameters

bytes

The number of bytes to be produced

Definition at line 98 of file stream_cipher.h.

                                      {
         T out(bytes);
         write_keystream(out);
         return out;
      }

References write_keystream().

maximum_keylength()

size_t Botan::SymmetricAlgorithm::maximum_keylength ( ) const

inlineinherited

Return the largest acceptable key length

Returns

maximum allowed key length

Definition at line 130 of file sym_algo.h.

{ return key_spec().maximum_keylength(); }

References key_spec().

minimum_keylength()

size_t Botan::SymmetricAlgorithm::minimum_keylength ( ) const

inlineinherited

Return the smallest acceptable key length

Returns

minimum allowed key length

Definition at line 136 of file sym_algo.h.

{ return key_spec().minimum_keylength(); }

References key_spec().

name()

std::string Botan::ChaCha::name ( ) const

overridevirtual

Return the name of this algorithm

Returns

the algorithm name

Implements Botan::SymmetricAlgorithm.

Definition at line 446 of file chacha.cpp.

                             {
   return fmt("ChaCha({})", m_rounds);
}

References Botan::fmt().

new_object()

std::unique_ptr< StreamCipher > Botan::ChaCha::new_object ( ) const

overridevirtual

Create a new uninitialized object of the same type

Returns

new object representing the same algorithm as *this

Implements Botan::StreamCipher.

Definition at line 368 of file chacha.cpp.

                                                     {
   return std::make_unique<ChaCha>(m_rounds);
}

provider()

std::string Botan::ChaCha::provider ( ) const

overridevirtual

Return the name of the provider implementing this object

Returns

provider information about this implementation. Default is "base", might also return "sse2", "avx2" or some other arbitrary string.

Reimplemented from Botan::StreamCipher.

Definition at line 112 of file chacha.cpp.

                                 {
#if defined(BOTAN_HAS_CHACHA_AVX512)
   if(auto feat = CPUID::check(CPUID::Feature::AVX512)) {
      return *feat;
   }
#endif
 
#if defined(BOTAN_HAS_CHACHA_AVX2)
   if(auto feat = CPUID::check(CPUID::Feature::AVX2)) {
      return *feat;
   }
#endif
 
#if defined(BOTAN_HAS_CHACHA_SIMD32)
   if(auto feat = CPUID::check(CPUID::Feature::SIMD_4X32)) {
      return *feat;
   }
#endif
 
   return "base";
}

References Botan::CPUFeature::AVX2, Botan::CPUFeature::AVX512, Botan::CPUID::check(), and Botan::CPUFeature::SIMD_4X32.

providers()

std::vector< std::string > Botan::StreamCipher::providers ( std::string_view algo_spec )

staticinherited

List the providers available for a given stream cipher

Returns

list of available providers for this algorithm, empty if not available

Definition at line 129 of file stream_cipher.cpp.

                                                                     {
   return probe_providers_of<StreamCipher>(algo_spec);
}

References Botan::probe_providers_of().

remaining_keystream_bytes()

std::optional< uint64_t > Botan::ChaCha::remaining_keystream_bytes ( ) const

overridevirtual

Many stream ciphers are internally based on encrypting a counter of some kind. If the counter wraps around, keystream bytes would be repeated.

This function returns the number of keystream bytes that can still be produced under the current key/nonce settings, if that limit fits in a uint64_t. If there is no specific limit (eg due to being based on permutations rather than a counter), or if the limit is at least 2**64 bytes (where consuming the entire keystream is not practically possible), then this function returns nullopt.

Note this returns nullopt if no key is set (there are no keystream bytes at all available, in that state) or potentially if the nonce is not set (as in some cases, such as ChaCha, the available counter bytes vary depending on the size of the nonce used).

Implements Botan::StreamCipher.

Definition at line 439 of file chacha.cpp.

                                                              {
   if(!has_keying_material() || m_iv_length != 12) {
      return std::nullopt;
   }
   return m_bytes_remaining;
}

References has_keying_material().

seek()

void Botan::ChaCha::seek ( uint64_t offset )

overridevirtual

Set the offset and the state used later to generate the keystream

Sets the state of the stream cipher and keystream according to the passed offset, exactly as if offset bytes had first been encrypted. The key and (if required) the IV have to be set before this can be called.

Note

Not all ciphers support seeking; such objects will throw Not_Implemented in this case. Use supports_seek() to query in advance.

Parameters

offset

the offset where we begin to generate the keystream

Implements Botan::StreamCipher.

Definition at line 450 of file chacha.cpp.

                                 {
   assert_key_material_set();
 
   const uint64_t block = offset / 64;
 
   if(m_iv_length == 12) {
      // 96 bit nonce implies a 32-bit counter; prevent seeking beyond that
      if((block >> 32) != 0) {
         throw Invalid_Argument("ChaCha::seek with 96-bit nonce limited to 2^32 blocks (256 GiB)");
      }
      m_state[12] = static_cast<uint32_t>(block);
      m_state[13] = m_state13_post_iv;
      m_bytes_remaining = chacha_96bit_nonce_cap - offset;
   } else {
      // 64-bit block counter spanning state words 12 and 13.
      m_state[12] = static_cast<uint32_t>(block);
      m_state[13] = m_state13_post_iv + static_cast<uint32_t>(block >> 32);
   }
 
   chacha(m_buffer.data(), m_buffer.size() / 64, m_state.data(), m_rounds);
   m_position = offset % 64;
}

References Botan::SymmetricAlgorithm::assert_key_material_set().

set_iv() [1/2]

void Botan::StreamCipher::set_iv ( const uint8_t iv[], size_t iv_len )

inlineinherited

Resync the cipher using the IV

Load IV into the stream cipher state. This should happen after the key is set (set_key()) and before any operation (encrypt(), decrypt() or seek()) is called.

If the cipher does not support IVs, then a call with an empty IV will be accepted and any other length will cause an Invalid_IV_Length exception.

Parameters

iv	the initialization vector
iv_len	the length of the IV in bytes

Definition at line 168 of file stream_cipher.h.

{ set_iv_bytes(iv, iv_len); }

References set_iv_bytes().

Referenced by Botan::Sodium::crypto_stream_salsa20(), Botan::Sodium::crypto_stream_salsa20_xor_ic(), Botan::Sodium::crypto_stream_xsalsa20(), Botan::Sodium::crypto_stream_xsalsa20_xor_ic(), Botan::Sodium::randombytes_buf_deterministic(), and Botan::SIV_Mode::set_ctr_iv().

set_iv() [2/2]

void Botan::StreamCipher::set_iv ( std::span< const uint8_t > iv )

inlineinherited

Resync the cipher using the IV

Parameters

iv	the initialization vector

Exceptions

Invalid_IV_Length

if an incompatible IV was passed.

Definition at line 175 of file stream_cipher.h.

{ set_iv_bytes(iv.data(), iv.size()); }

References set_iv_bytes().

set_key() [1/3]

void Botan::SymmetricAlgorithm::set_key ( const OctetString & key )

inherited

Set the symmetric key of this object.

Parameters

key	the SymmetricKey to be set.

Definition at line 14 of file sym_algo.cpp.

                                                       {
   set_key(std::span{key.begin(), key.length()});
}

References Botan::OctetString::begin(), Botan::OctetString::length(), and set_key().

Referenced by Botan::create_aes_row_generator(), Botan::Sodium::crypto_stream_salsa20(), Botan::Sodium::crypto_stream_salsa20_xor_ic(), Botan::Sodium::crypto_stream_xsalsa20(), Botan::Sodium::crypto_stream_xsalsa20_xor_ic(), Botan::FPE::fe1_decrypt(), Botan::FPE::fe1_encrypt(), Botan::Sphincs_Hash_Functions_Sha2::PRF_msg(), Botan::Sodium::randombytes_buf_deterministic(), Botan::TLS::TLS_NULL_HMAC_AEAD_Mode::reset(), and set_key().

set_key() [2/3]

void Botan::SymmetricAlgorithm::set_key ( const uint8_t key[], size_t length )

inlineinherited

Set the symmetric key of this object.

Parameters

key	the to be set as a byte array.
length	in bytes of key param

Definition at line 162 of file sym_algo.h.

{ set_key(std::span{key, length}); }

References set_key().

Referenced by set_key().

set_key() [3/3]

void Botan::SymmetricAlgorithm::set_key ( std::span< const uint8_t > key )

inherited

Set the symmetric key of this object.

Parameters

key	the contiguous byte range to be set.

Definition at line 22 of file sym_algo.cpp.

                                                           {
   if(!valid_keylength(key.size())) {
      throw Invalid_Key_Length(name(), key.size());
   }
   key_schedule(key);
}

References name(), and valid_keylength().

supports_seek()

bool Botan::ChaCha::supports_seek ( ) const

inlineoverridevirtual

Test whether this cipher supports seeking within the keystream

Returns

true if this cipher implements seek(); false if seek() will throw Not_Implemented for any offset.

Implements Botan::StreamCipher.

Definition at line 49 of file chacha.h.

{ return true; }

valid_iv_length()

bool Botan::ChaCha::valid_iv_length ( size_t iv_len ) const

overridevirtual

Test if a nonce length is valid for this cipher

Parameters

iv_len

the length of the IV in bytes

Returns

if the length is valid for this algorithm

Reimplemented from Botan::StreamCipher.

Definition at line 372 of file chacha.cpp.

                                                {
   return (iv_len == 0 || iv_len == 8 || iv_len == 12 || iv_len == 24);
}

valid_keylength()

bool Botan::SymmetricAlgorithm::valid_keylength ( size_t length ) const

inlineinherited

Check whether a given key length is valid for this algorithm.

Parameters

length

the key length to be checked.

Returns

true if the key length is valid.

Definition at line 143 of file sym_algo.h.

{ return key_spec().valid_keylength(length); }

References key_spec().

Referenced by set_key().

write_keystream() [1/2]

void Botan::StreamCipher::write_keystream ( std::span< uint8_t > out )

inlineinherited

Fill a given buffer with keystream bytes

The contents of out are ignored/overwritten

Parameters

out	the byte array to hold the keystream

Definition at line 88 of file stream_cipher.h.

{ generate_keystream(out.data(), out.size()); }

References generate_keystream().

write_keystream() [2/2]

void Botan::StreamCipher::write_keystream ( uint8_t out[], size_t len )

inlineinherited

Write keystream bytes to a buffer

The contents of out are ignored/overwritten

Parameters

out	the byte array to hold the keystream
len	the length of out in bytes

Definition at line 79 of file stream_cipher.h.

{ generate_keystream(out, len); }

References generate_keystream().

Referenced by Botan::Sodium::crypto_stream_salsa20(), Botan::Sodium::crypto_stream_xsalsa20(), keystream_bytes(), and Botan::Sodium::randombytes_buf_deterministic().

---

The documentation for this class was generated from the following files:

• src/lib/stream/chacha/chacha.h
• src/lib/stream/chacha/chacha.cpp
• src/lib/stream/chacha/chacha_avx2/chacha_avx2.cpp
• src/lib/stream/chacha/chacha_avx512/chacha_avx512.cpp
• src/lib/stream/chacha/chacha_simd32/chacha_simd32.cpp