Maven module :un.api : api-encoding :
Class : un.impl.cryptography.algorithms.Salsa20
Extends/Implements : un.impl.cryptography.algorithms.CipherAlgorithm
Subclasses : -

A word is an element of { 0, 1, ... , 2³²−1 }.
http://edipermadi.files.wordpress.com/2008/06/salsa20-spec.pdf
author Bertrand COTE

Variables : -
Functions : cipher, invCipher, getNewCipher, circularLeftShift, quarterRound, rowRound, columnRound, doubleRound, littleEndian, invLittleEndian, hash, expansion, encryption, main, byteArrayToHexString, byteArrayToString

public byte[] cipher (byte[] input)

public byte[] invCipher (byte[] input)

public CipherAlgorithm getNewCipher (byte[] key)

Circular left shift of the register.
E.g:
circularLeftShift(0xc0a8787e, 5) returns 0x150f0fd8
param register
param leftShift
return

public int circularLeftShift (int register, int leftShift)

Computes zWords as:

z1 = y1 ⊕ ((y0 + y3 ) <<< 7)

z2 = y2 ⊕ ((z1 + y0 ) <<< 9)

z3 = y3 ⊕ ((z2 + z1 ) <<< 13)

z0 = y0 ⊕ ((z3 + z2 ) <<< 18)

(<<< means circular left shift)

@param y a 4-word sequence.
@return zWords a 4-word sequence if y is a 4-word sequence.

public int[] quarterRound (int[] y)

(z0 , z1 , z2 , z3 ) = quarterRound(y0 , y1 , y2 , y3 )

(z5 , z6 , z7 , z4 ) = quarterRound(y5 , y6 , y7 , y4 )

(z10 , z11 , z8 , z9 ) = quarterRound(y10 , y11 , y8 , y9 )

(z15 , z12 , z13 , z14 ) = quarterRound(y15 , y12 , y13 , y14 )

@param y a 16-word sequence.
@return z a 16-word sequence if y is a 16-word sequence.

public int[] rowRound (int[] y)

(y0 , y4 , y8 , y12 ) = quarterRound(x0 , x4 , x8 , x12 )

(y5 , y9 , y13 , y1 ) = quarterRound(x5 , x9 , x13 , x1 )

(y10 , y14 , y2 , y6 ) = quarterRound(x10 , x14 , x2 , x6 )

(y15 , y3 , y7 , y11 ) = quarterRound(x15 , x3 , x7 , x11 )

@param x a 16-word sequence.
@return y a 16-word sequence.

public int[] columnRound (int[] x)

A double round is a column round followed by a row round:
doubleRound(x) = rowRound(columnRound(x)).
One can visualize a double round as modifying the columns of the input in
parallel, and then modifying the rows in parallel. Each word is modified
twice.
param x a 16-word sequence.
return a 16-word sequence.

public int[] doubleRound (int[] x)

If b = (b0 , b1 , b2 , b3 ) then
littleEndian(b) = b3*2²⁴ + b2*2¹⁶ + b1*2⁸ + b0.
Note that littleEndian is invertible.
param b a 4-byte sequence.
return a word.

public int littleEndian (byte[] b)

public byte[] invLittleEndian (int w)

param x a 64-byte sequence.
return a 64-byte sequence.

public byte[] hash (byte[] x)

“Expansion” refers to the expansion of (k, n) into Salsa20_k (n).
It also refers to the expansion of k into a long stream of Salsa20k
outputs for various n’s; see Section 10.
The constants σ0 σ1 σ2 σ3 and τ0 τ1 τ2 τ3 are “expand 32-byte k” and
“expand 16-byte k” in ASCII.
param  k a 32-byte or 16-byte sequence.
param  n a 16-byte sequence.
return  a 64-byte sequence.

public byte[] expansion (byte[] k, byte[] n)

The Salsa20 encryption of m with nonce v under key k, denoted
Salsa20_k(v)⊕m, is an l-byte sequence.
param  k the secret key: a 32-byte or 16-byte sequence (preferably 32 bytes).
param  v the nonce: an 8-byte sequence (a unique message number).
param  m the plaintext message: an l-byte sequence for some l ∈ { 0, 1, ... , 2⁷⁰ }.
return  the ciphertext message: an l-byte sequence (Salsa20_k(v)⊕m).

public byte[] encryption (byte[] k, byte[] v, byte[] m)

public void main (String[] args)

public String byteArrayToHexString (byte[] byteArray)

public String byteArrayToString (byte[] byteArray)