Paillier not working with scalar non-integer float

[kostrom]

If someone tries to work with float values in paillier, it doesn't work, but it works for integers. If it only supports integers, you may want to raise an exception, in keeping with how you handle some other illegal operations.

see https://stackoverflow.com/questions/78335087/the-sum-does-not-get-decrypted

[serengil]

Float numbers are not invalid actually. They are converted to integers for that module.

cs = LightPHE(algorithm_name = "Paillier")

m1 = 17
c1 = cs.encrypt(m1)

# increasing something 5%
k = 1.05

# scalar multiplication - private key is not required!
c4 = k * c1

# proof of work
assert cs.decrypt(c4) == k * m1

Besides, if you set your plaintext as tensor, then you are able to restore that float number.

cs = LightPHE(algorithm_name = "Paillier")

m = [1.5]
c = cs.encrypt(m)
p = cs.decrypt(c)
assert p[0] == 1.5

[kostrom]

`from lightphe import LightPHE
cs = LightPHE(algorithm_name="Paillier")
def validate(m): return m == cs.decrypt(cs.encrypt(m))

assert validate(1)
assert validate([1.5])
assert validate(1.0)
assert validate(1.5) # does not work for scalar float (with a non-integer value)
`
Thanks for the workaround. I notice that the working vector of float creates a Fraction object, but the scalar float goes into parse_int and breaks it down to a fraction form, but returns a Ciphertext object of a very large integer, which it doesn't know how to reverse.

I guess the title of the bug report is completely wrong, though -- sorry about that. If I'd thought about it, I'd have realized something that works with integers can work with fractions of integers.

[serengil]

They are all working for me. Are you using latest version?

[kostrom]

pip says this is version 0.0.6

[serengil]

would you please share all exception message?

[serengil]

btw python version may be the root cause of your problem.

i am using Python 3.9.16

[kostrom]

Python 3.10.4 (tags/v3.10.4:9d38120, Mar 23 2022, 23:13:41) [MSC v.1929 64 bit (AMD64)] on win32
There are no exceptions (unless you count the assert).
It just returns a very large integer instead of the original float.
I updated the issue summary.

from lightphe import LightPHE  
cs = LightPHE(algorithm_name="Paillier")  

m = 0.5  
c = cs.encrypt(m)  
print (c)  
print (c.value)  
print (cs.decrypt(c))  

The result is a different large integer each time. One example:
Ciphertext(4922236528608796958846746588856423007916048798962477533781817619365633697325781550310212188324426679830638156638168677716104162861723368950471576089968798265186067536585262890999551828526603098457138708105316241290356667810727996717063041280990292421509852573848746382971495371575884363892331801459088266056263296822284217735228810846513811562773585729263266463491832609884275528416373445393310448315775555480589931990786433374114491875143152201524542983831458022888057533769829260893420154296328186405682975065490419261182064893854706074644935068680571429787260863682691199488370523205802299040717157400554985373)
4922236528608796958846746588856423007916048798962477533781817619365633697325781550310212188324426679830638156638168677716104162861723368950471576089968798265186067536585262890999551828526603098457138708105316241290356667810727996717063041280990292421509852573848746382971495371575884363892331801459088266056263296822284217735228810846513811562773585729263266463491832609884275528416373445393310448315775555480589931990786433374114491875143152201524542983831458022888057533769829260893420154296328186405682975065490419261182064893854706074644935068680571429787260863682691199488370523205802299040717157400554985373
3160776990604745647081572122326825228093787522500982730374347988572421971214894550600891079327673062817591884978456486978621806738130920750356955734498673096320017239353437210121462431193272851721939264910466572918152023133068103002383357016447565929890091709586032192185552280463164426557306804290606846899

[kostrom]

Actually, looking at the source, I might be able to submit an MR, but if you're not reproducing the issue ... that might be counterproductive.

[serengil]

Yes please

[kostrom]

My quick fix of handling float like [float] broke a few other things. Fraction doesn't have value, and why can't we multiply a Fraction by a constant?

Is there a quick way to convert between Ciphertext and Fraction?

[serengil]

It does!

https://github.com/serengil/LightPHE/blob/master/tests/test_tensors.py#L64

As seen this is checked in unit tests and run successfully in github actions. I think your problem is because of your python version.

[serengil]

you cannot convert ciphertext to fraction. you can only convert a float value to fraction. then, you can encrypt its dividend and divisor separately as shown here: https://github.com/serengil/LightPHE/blob/master/lightphe/__init__.py#L178

[kostrom]

Sorry, I misspoke. Multiply Ciphertext (of a constant) and Fraction.
Ciphertext and Tensor each have dunder mul, but they don't like each other.

[kostrom]

I'll have to deal with another fire, then get a better understanding of the class structure before I give this another go.

[serengil]

@kostrom you may consider to make your python version same with me

[serengil]

Closed due to inactivity