With composition
This document explains how to combine compiled functions with the composable
flag in Concrete.
By setting the composable
flag to True
, you can compile a function such that its outputs can be reused as inputs. For example, you can then easily compute f(f(x))
or f**i(x) = f(f(...(f(x) ..))
for a non-encrypted integer i
variable, which is usually required for recursions.
Here is an example:
from concrete import fhe
@fhe.compiler({"counter": "encrypted"})
def increment(counter):
return (counter + 1) % 100
print("Compiling `increment` function")
increment_fhe = increment.compile(list(range(0, 100)), composable=True)
print("Generating keyset ...")
increment_fhe.keygen()
print("Encrypting the initial counter value")
counter = 0
counter_enc = increment_fhe.encrypt(counter)
print(f"| iteration || decrypted | cleartext |")
for i in range(10):
counter_enc = increment_fhe.run(counter_enc)
counter = increment(counter)
# For demo purpose; no decryption is needed.
counter_dec = increment_fhe.decrypt(counter_enc)
print(f"| {i} || {counter_dec:<9} | {counter:<9} |")
Remark that this option is the equivalent to using the fhe.AllComposable
policy of modules. In particular, the same limitations may occur (see limitations documentation section).
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