29 lines
1.0 KiB
TypeScript
29 lines
1.0 KiB
TypeScript
export const galoisMultiplyBy2 = (value: number): number => {
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return (value << 1) ^ ((value & 0x80) ? 0x1b : 0x00)
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}
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export const galoisMultiplyBy3 = (value: number): number => {
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return galoisMultiplyBy2(value) ^ value
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}
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const clampToByte = (value: number): number => {
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return value & 0xFF
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}
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export const mixColumns = (state: number[][]): number[][] => {
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const result: number[][] = [
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[0, 0, 0, 0],
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[0, 0, 0, 0],
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[0, 0, 0, 0],
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[0, 0, 0, 0]
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]
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for (let col = 0; col < 4; col++) {
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result[0][col] = clampToByte(galoisMultiplyBy2(state[0][col]) ^ galoisMultiplyBy3(state[1][col]) ^ state[2][col] ^ state[3][col])
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result[1][col] = clampToByte(state[0][col] ^ galoisMultiplyBy2(state[1][col]) ^ galoisMultiplyBy3(state[2][col]) ^ state[3][col])
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result[2][col] = clampToByte(state[0][col] ^ state[1][col] ^ galoisMultiplyBy2(state[2][col]) ^ galoisMultiplyBy3(state[3][col]))
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result[3][col] = clampToByte(galoisMultiplyBy3(state[0][col]) ^ state[1][col] ^ state[2][col] ^ galoisMultiplyBy2(state[3][col]))
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}
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return result
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} |