Commit3bf7b2e

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Choose blinding factor relatively prime to N

This is a requirement for RSA blinding, but wasn't implemented yet.

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+15

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Lines changed: 6 additions & 4 deletions

Original file line number	Diff line number	Diff line change
`@@ -4,11 +4,13 @@ Python-RSA changelog`
`4`	`4`	`Version 4.3 - released 2020-06-12`
`5`	`5`	`----------------------------------------`
`6`	`6`
`7`		`-Version 4.3 is a re-tagged release of version 4.0. It is the last to support`
`8`		-Python 2.7. This is now made explicit in the `python_requires` argument in
`9`		-`setup.py`.
	`7`	`+Version 4.3 isalmosta re-tagged release of version 4.0. It is the last to`
	`8`	+supportPython 2.7. This is now made explicit in the `python_requires` argument
	`9`	+in`setup.py`.
`10`	`10`
`11`		`-There are no functional differences.`
	`11`	`+Two security fixes have also been backported, so 4.3 = 4.0 + these two fixes.`
	`12`	`+`
	`13`	`+- Choose blinding factor relatively prime to N. Thanks Christian Heimes for pointing this out.`
`12`	`14`
`13`	`15`
`14`	`16`	`Version 4.0 - released 2018-09-16`

Lines changed: 9 additions & 2 deletions

Original file line number	Diff line number	Diff line change
`@@ -417,6 +417,13 @@ def __ne__(self, other):`
`417`	`417`	`def__hash__(self):`
`418`	`418`	`returnhash((self.n,self.e,self.d,self.p,self.q,self.exp1,self.exp2,self.coef))`
`419`	`419`
	`420`	`+def_get_blinding_factor(self):`
	`421`	`+for_inrange(1000):`
	`422`	`+blind_r=rsa.randnum.randint(self.n-1)`
	`423`	`+ifrsa.prime.are_relatively_prime(self.n,blind_r):`
	`424`	`+returnblind_r`
	`425`	`+raiseRuntimeError('unable to find blinding factor')`
	`426`	`+`
`420`	`427`	`defblinded_decrypt(self,encrypted):`
`421`	`428`	`"""Decrypts the message using blinding to prevent side-channel attacks.`
`422`	`429`
`@@ -427,7 +434,7 @@ def blinded_decrypt(self, encrypted):`
`427`	`434`	`:rtype: int`
`428`	`435`	`"""`
`429`	`436`
`430`		`-blind_r=rsa.randnum.randint(self.n-1)`
	`437`	`+blind_r=self._get_blinding_factor()`
`431`	`438`	`blinded=self.blind(encrypted,blind_r)# blind before decrypting`
`432`	`439`	`decrypted=rsa.core.decrypt_int(blinded,self.d,self.n)`
`433`	`440`
`@@ -443,7 +450,7 @@ def blinded_encrypt(self, message):`
`443`	`450`	`:rtype: int`
`444`	`451`	`"""`
`445`	`452`
`446`		`-blind_r=rsa.randnum.randint(self.n-1)`
	`453`	`+blind_r=self._get_blinding_factor()`
`447`	`454`	`blinded=self.blind(message,blind_r)# blind before encrypting`
`448`	`455`	`encrypted=rsa.core.encrypt_int(blinded,self.d,self.n)`
`449`	`456`	`returnself.unblind(encrypted,blind_r)`

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