Enhancing Security of Telemedicine Data: A Multi-Scroll Chaotic System for ECG Signal Encryption and RF Transmission

. 2024 Sep 14;26(9):787. doi: 10.3390/e26090787

Algorithm 4 Decryption of ECG Signal

Input Encrypted signal

E C G_e n c r y p t

, synchronization signal
Output Decrypted ECG signal

E C G_d e c

1:
procedure Observer Synchronization Process
2:
Initialize parameters
3:
Initialize observer gains
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$N \leftarrow$ Length of $d S$
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Initialize states
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$d t \leftarrow$ Defined time step
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for $i \leftarrow 1$ to $N - 1$ do
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$x 1 s [i + 1] \leftarrow x 1 s [i] + h \cdot (x 2 s [i] + l 1 \cdot (x 1 [i] - x 1 s [i]))$
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$x 2 s [i + 1] \leftarrow x 2 s [i] + h \cdot (x 3 s [i] + l 2 \cdot (x 1 [i] - x 1 s [i]))$
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$x 3 s [i + 1] \leftarrow x 3 s [i] + h \cdot (- a 1 \cdot x 1 s [i] - a 2 \cdot x 2 s [i] - a 3 \cdot x 3 s [i] + x 4 s [i] + l 3 \cdot (x 1 [i] - x 1 s [i]))$
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$x 4 s [i + 1] \leftarrow x 4 s [i] + h \cdot 4 \cdot (x 1 [i] - x 1 s [i])$
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end for
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$E C G_d e c \leftarrow E C G_e n c r y p t - x 3 s$
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return $E C G_d e c$
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end procedure