Method SetKey

src/crypto/chacha20.cpp:24–50

static const unsigned char tau[] = "expand 16-byte k";

void ChaCha20::SetKey(const unsigned char* k, size_t keylen)
{
    const unsigned char *constants;

    input[4] = ReadLE32(k + 0);
    input[5] = ReadLE32(k + 4);
    input[6] = ReadLE32(k + 8);
    input[7] = ReadLE32(k + 12);
    if (keylen == 32) { /* recommended */
        k += 16;
        constants = sigma;
    } else { /* keylen == 16 */
        constants = tau;
    }
    input[8] = ReadLE32(k + 0);
    input[9] = ReadLE32(k + 4);
    input[10] = ReadLE32(k + 8);
    input[11] = ReadLE32(k + 12);
    input[0] = ReadLE32(constants + 0);
    input[1] = ReadLE32(constants + 4);
    input[2] = ReadLE32(constants + 8);
    input[3] = ReadLE32(constants + 12);
    input[12] = 0;
    input[13] = 0;
    input[14] = 0;
    input[15] = 0;
}

ChaCha20::ChaCha20()
{