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| author | Sybren A. Stüvel <sybren@stuvel.eu> | 2021-03-29 23:24:28 +0200 |
|---|---|---|
| committer | Sybren A. Stüvel <sybren@stuvel.eu> | 2021-03-29 23:24:28 +0200 |
| commit | 483700ada63972e600c7770c124f5aa0568dabf7 (patch) | |
| tree | be9bdb57e8feee3d683675de8ab9bce7fba007e6 | |
| parent | 35e962d9ce424ef5ea35a9787b7b165fc034712d (diff) | |
| download | rsa-git-483700ada63972e600c7770c124f5aa0568dabf7.tar.gz | |
Use Chinese Remainder Theorem when decrypting with private key
Use the Chinese Remainder Theorem when decrypting with private key, as that
makes the decryption 2-4x faster.
This fixes #163.
| -rw-r--r-- | CHANGELOG.md | 3 | ||||
| -rw-r--r-- | rsa/key.py | 11 |
2 files changed, 13 insertions, 1 deletions
diff --git a/CHANGELOG.md b/CHANGELOG.md index 82a9ab7..3078332 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -8,6 +8,9 @@ - Added marker file for PEP 561. This will allow type checking tools in dependent projects to use type annotations from Python-RSA ([#136](https://github.com/sybrenstuvel/python-rsa/pull/136)). +- Use the Chinese Remainder Theorem when decrypting with a private key. This + makes decryption 2-4x faster + ([#163](https://github.com/sybrenstuvel/python-rsa/pull/163)). ## Version 4.7.2 - released 2021-02-24 @@ -473,7 +473,16 @@ class PrivateKey(AbstractKey): # Blinding and un-blinding should be using the same factor blinded, blindfac_inverse = self.blind(encrypted) - decrypted = rsa.core.decrypt_int(blinded, self.d, self.n) + + # Instead of using the core functionality, use the Chinese Remainder + # Theorem and be 2-4x faster. This the same as: + # + # decrypted = rsa.core.decrypt_int(blinded, self.d, self.n) + s1 = pow(blinded, self.exp1, self.p) + s2 = pow(blinded, self.exp2, self.q) + h = ((s1 - s2) * self.coef) % self.p + decrypted = s2 + self.q * h + return self.unblind(decrypted, blindfac_inverse) def blinded_encrypt(self, message: int) -> int: |