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Choose Function (Ch) - Boolean Algebra
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Inputs Outputs
X Y Z Q
0 X 0 0
0 X 1 1
1 0 X 0
1 1 X 1

Choose function (or Ch Function) (sometimes if-then-else or ITE) is a Boolean function that represents a 2:1 MUX. The choose function is frequently found in various cryptographic hash functions.

Equation Ch left-parenthesis x comma y comma z right-parenthesis equals StartLayout Enlarged left-brace 1st Row 1st Column y comma 2nd Column if x equals 1 2nd Row 1st Column z comma 2nd Column if x equals 0 EndLayout


Which can be implemented as:

Equation Ch left-parenthesis x comma y comma z right-parenthesis equals left-parenthesis x logical-and y right-parenthesis logical-or left-parenthesis x overbar logical-and z right-parenthesis

The xor version is sometimes more commonly in field such as cryptography.

Equation Ch left-parenthesis x comma y comma z right-parenthesis equals left-parenthesis x logical-and y right-parenthesis circled-plus left-parenthesis x overbar logical-and z right-parenthesis

See also[edit]