package chacha20

Import Path
	vendor/golang.org/x/crypto/chacha20 (on go.dev)

Dependency Relation
	imports 6 packages, and imported by one package


Involved Source Files

	
		Package chacha20 implements the ChaCha20 and XChaCha20 encryption algorithms
		as specified in RFC 8439 and draft-irtf-cfrg-xchacha-01.

	    chacha_noasm.go
	    xor.go


Package-Level Type Names (only one, which is exported)


	/* sort exporteds by:  |  */
	
		Cipher is a stateful instance of ChaCha20 or XChaCha20 using a particular key
		and nonce. A *Cipher implements the cipher.Stream interface.

		
			
		
			
				SetCounter sets the Cipher counter. The next invocation of XORKeyStream will
				behave as if (64 * counter) bytes had been encrypted so far.
				
				To prevent accidental counter reuse, SetCounter panics if counter is less
				than the current value.
				
				Note that the execution time of XORKeyStream is not independent of the
				counter value.

			
				XORKeyStream XORs each byte in the given slice with a byte from the
				cipher's key stream. Dst and src must overlap entirely or not at all.
				
				If len(dst) < len(src), XORKeyStream will panic. It is acceptable
				to pass a dst bigger than src, and in that case, XORKeyStream will
				only update dst[:len(src)] and will not touch the rest of dst.
				
				Multiple calls to XORKeyStream behave as if the concatenation of
				the src buffers was passed in a single run. That is, Cipher
				maintains state and does not reset at each XORKeyStream call.

			
		
			*Cipher : crypto/cipher.Stream
		
			func NewUnauthenticatedCipher(key, nonce []byte) (*Cipher, error)
			
		
			




Package-Level Functions (total 6, in which 2 are exported)


	
		HChaCha20 uses the ChaCha20 core to generate a derived key from a 32 bytes
		key and a 16 bytes nonce. It returns an error if key or nonce have any other
		length. It is used as part of the XChaCha20 construction.


	
		NewUnauthenticatedCipher creates a new ChaCha20 stream cipher with the given
		32 bytes key and a 12 or 24 bytes nonce. If a nonce of 24 bytes is provided,
		the XChaCha20 construction will be used. It returns an error if key or nonce
		have any other length.
		
		Note that ChaCha20, like all stream ciphers, is not authenticated and allows
		attackers to silently tamper with the plaintext. For this reason, it is more
		appropriate as a building block than as a standalone encryption mechanism.
		Instead, consider using package golang.org/x/crypto/chacha20poly1305.


	


Package-Level Constants (total 10, in which 3 are exported)


	
		KeySize is the size of the key used by this cipher, in bytes.


	
		NonceSize is the size of the nonce used with the standard variant of this
		cipher, in bytes.
		
		Note that this is too short to be safely generated at random if the same
		key is reused more than 2³² times.


	
		NonceSizeX is the size of the nonce used with the XChaCha20 variant of
		this cipher, in bytes.