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Referring to the question 11272, I have an experiment with MiniNero:

tx_pub_key = "f6d51a0cabd6a68f2c4960bc06b4132d6b937622b8954ea95851aa5f3b32c1de"
pri_view_key = "89a705a1a6427e7a19fd17a78d4a5c35bcb9ce4af74d6c180d5e39909694ab0a"
aR = MiniNero.mul8(MiniNero.scalarmultKey(tx_pub_key, pri_view_key))
tmp = MiniNero.cn_fast_hash(aR+"00")
res = MiniNero.cn_fast_hash("616d6f756e74"+tmp) #616d6f756e74 is ASCII of "amount"

Then I get the result:

0e37ec1966076a6c5c6f15b1ad32f415b5f3e2426c1dc8c95c73b72cabe02168

The last step is to XOR each first 8-byte data:

amount = MiniNero.xor("54f95f7d7f4d1e2a", "0e37ec1966076a6c")

However, the result is not right. Am I doing something wrong? Please help to solve this, Thanks!

BTW, I get 54f95f7d7f4d1e2a from ecdhInfo (explorer)

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You haven't reduced tmp. I.e.

tmp = MiniNero.sc_reduce_key(MiniNero.cn_fast_hash(aR+"00"))

Hs in the referenced question's answer refers to Hash to scalar, not simply hash. Otherwise keccak would have been written in place of Hs.

Thus, following your experiment through with the correction, I calculate 1 XMR:

tx_pub_key = "f6d51a0cabd6a68f2c4960bc06b4132d6b937622b8954ea95851aa5f3b32c1de"
pri_view_key = "89a705a1a6427e7a19fd17a78d4a5c35bcb9ce4af74d6c180d5e39909694ab0a"
aR = MiniNero.mul8(MiniNero.scalarmultKey(tx_pub_key, pri_view_key))
tmp = MiniNero.sc_reduce_key(MiniNero.cn_fast_hash(aR+"00"))
res = MiniNero.cn_fast_hash("616d6f756e74"+tmp) #616d6f756e74 is ASCII of "amount"
amount = MiniNero.xor("54f95f7d7f4d1e2a",res[:16])[:16]
print(MiniNero.hexToInt(amount)*1e-12)

Which yields:

1.0
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  • Thanks you very much!! BTW, does it indicate that it should multiple *1e-12 after the resource? Where can I find it?
    – Mooooo
    Commented Apr 30, 2020 at 3:06
  • 1
    web.getmonero.org/resources/moneropedia/atomic-units.html - 1 XMR is 1,000,000,000,000 atomic units. As amounts are stored in atomic units, to view in XMR one must multiply by 1e-12.
    – jtgrassie
    Commented Apr 30, 2020 at 3:08
  • May I know why it needs to hexToInt() in the last step? Is there a monero-project version of hexToInt()? Thanks!
    – Mooooo
    Commented May 15, 2020 at 8:55
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    Because most of the MiniNero python methods return hex strings. The last step above needs it as an integer to multiply by 1e-12 to convert atomic units to XMR.
    – jtgrassie
    Commented May 15, 2020 at 13:13

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