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Merge pull request github#6055 from RasmusWL/rsa-modeling
Approved by yoff
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‎docs/codeql/support/reusables/frameworks.rst

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@@ -176,3 +176,4 @@ Python built-in support
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cryptography, Cryptography library
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pycryptodome, Cryptography library
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pycryptodomex, Cryptography library
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rsa, Cryptography library

‎python/change-notes/2021-06-09-rsa-add-modeling.md

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lgtm,codescanning
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* Added modeling of the PyPI package `rsa`.

‎python/ql/src/semmle/python/Frameworks.qll

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@@ -20,6 +20,7 @@ private import semmle.python.frameworks.Mysql
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private import semmle.python.frameworks.MySQLdb
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private import semmle.python.frameworks.Psycopg2
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private import semmle.python.frameworks.PyMySQL
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private import semmle.python.frameworks.Rsa
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private import semmle.python.frameworks.Simplejson
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private import semmle.python.frameworks.Stdlib
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private import semmle.python.frameworks.Tornado

‎python/ql/src/semmle/python/frameworks/Rsa.qll

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/**
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* Provides classes modeling security-relevant aspects of the `rsa` PyPI package.
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* See https://stuvel.eu/python-rsa-doc/.
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*/
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private import python
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private import semmle.python.dataflow.new.DataFlow
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private import semmle.python.dataflow.new.TaintTracking
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private import semmle.python.Concepts
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private import semmle.python.ApiGraphs
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/**
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* Provides models for the `rsa` PyPI package.
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* See https://stuvel.eu/python-rsa-doc/.
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*/
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private module Rsa {
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/**
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* A call to `rsa.newkeys`
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*
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* See https://stuvel.eu/python-rsa-doc/reference.html#rsa.newkeys
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*/
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class RsaNewkeysCall extends Cryptography::PublicKey::KeyGeneration::RsaRange,
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DataFlow::CallCfgNode {
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RsaNewkeysCall() { this = API::moduleImport("rsa").getMember("newkeys").getACall() }
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override DataFlow::Node getKeySizeArg() {
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result in [this.getArg(0), this.getArgByName("nbits")]
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}
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}
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/**
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* A call to `rsa.encrypt`
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*
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* See https://stuvel.eu/python-rsa-doc/reference.html#rsa.encrypt
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*/
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class RsaEncryptCall extends Cryptography::CryptographicOperation::Range, DataFlow::CallCfgNode {
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RsaEncryptCall() { this = API::moduleImport("rsa").getMember("encrypt").getACall() }
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override Cryptography::CryptographicAlgorithm getAlgorithm() { result.getName() = "RSA" }
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override DataFlow::Node getAnInput() {
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result in [this.getArg(0), this.getArgByName("message")]
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}
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}
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/**
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* A call to `rsa.decrypt`
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*
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* See https://stuvel.eu/python-rsa-doc/reference.html#rsa.decrypt
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*/
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class RsaDecryptCall extends Cryptography::CryptographicOperation::Range, DataFlow::CallCfgNode {
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RsaDecryptCall() { this = API::moduleImport("rsa").getMember("decrypt").getACall() }
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override Cryptography::CryptographicAlgorithm getAlgorithm() { result.getName() = "RSA" }
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override DataFlow::Node getAnInput() { result in [this.getArg(0), this.getArgByName("crypto")] }
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}
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/**
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* A call to `rsa.sign`, which both hashes and signs in the input message.
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*
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* See https://stuvel.eu/python-rsa-doc/reference.html#rsa.sign
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*/
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class RsaSignCall extends Cryptography::CryptographicOperation::Range, DataFlow::CallCfgNode {
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RsaSignCall() { this = API::moduleImport("rsa").getMember("sign").getACall() }
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override Cryptography::CryptographicAlgorithm getAlgorithm() {
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// signature part
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result.getName() = "RSA"
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or
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// hashing part
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exists(StrConst str, DataFlow::Node hashNameArg |
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hashNameArg in [this.getArg(2), this.getArgByName("hash_method")] and
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DataFlow::exprNode(str) = hashNameArg.getALocalSource() and
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result.matchesName(str.getText())
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)
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}
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override DataFlow::Node getAnInput() {
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result in [this.getArg(0), this.getArgByName("message")]
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}
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}
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/**
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* A call to `rsa.verify`
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*
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* See https://stuvel.eu/python-rsa-doc/reference.html#rsa.verify
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*/
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class RsaVerifyCall extends Cryptography::CryptographicOperation::Range, DataFlow::CallCfgNode {
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RsaVerifyCall() { this = API::moduleImport("rsa").getMember("verify").getACall() }
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override Cryptography::CryptographicAlgorithm getAlgorithm() {
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// note that technically there is also a hashing operation going on but we don't
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// know what algorithm is used up front, since it is encoded in the signature
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result.getName() = "RSA"
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}
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override DataFlow::Node getAnInput() {
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result in [this.getArg(0), this.getArgByName("message")]
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or
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result in [this.getArg(1), this.getArgByName("signature")]
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}
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}
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/**
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* A call to `rsa.compute_hash`
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*
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* See https://stuvel.eu/python-rsa-doc/reference.html#rsa.compute_hash
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*/
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class RsaComputeHashCall extends Cryptography::CryptographicOperation::Range,
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DataFlow::CallCfgNode {
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RsaComputeHashCall() { this = API::moduleImport("rsa").getMember("compute_hash").getACall() }
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override Cryptography::CryptographicAlgorithm getAlgorithm() {
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exists(StrConst str, DataFlow::Node hashNameArg |
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hashNameArg in [this.getArg(1), this.getArgByName("method_name")] and
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DataFlow::exprNode(str) = hashNameArg.getALocalSource() and
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result.matchesName(str.getText())
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)
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}
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override DataFlow::Node getAnInput() {
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result in [this.getArg(0), this.getArgByName("message")]
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}
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}
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/**
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* A call to `rsa.sign_hash`
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*
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* See https://stuvel.eu/python-rsa-doc/reference.html#rsa.sign_hash
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*/
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class RsaSignHashCall extends Cryptography::CryptographicOperation::Range, DataFlow::CallCfgNode {
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RsaSignHashCall() { this = API::moduleImport("rsa").getMember("sign_hash").getACall() }
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override Cryptography::CryptographicAlgorithm getAlgorithm() { result.getName() = "RSA" }
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override DataFlow::Node getAnInput() {
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result in [this.getArg(0), this.getArgByName("hash_value")]
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}
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}
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}

‎python/ql/test/library-tests/frameworks/rsa/ConceptsTest.expected

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‎python/ql/test/library-tests/frameworks/rsa/ConceptsTest.ql

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import python
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import experimental.meta.ConceptsTest

‎python/ql/test/library-tests/frameworks/rsa/InlineTaintTest.expected

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argumentToEnsureNotTaintedNotMarkedAsSpurious
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untaintedArgumentToEnsureTaintedNotMarkedAsMissing
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failures

‎python/ql/test/library-tests/frameworks/rsa/InlineTaintTest.ql

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import experimental.meta.InlineTaintTest

‎python/ql/test/library-tests/frameworks/rsa/test_rsa.py

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# Following examples from https://stuvel.eu/python-rsa-doc/usage.html
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import rsa
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# using a rather low keysize, since otherwise it takes quite long to run.
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(public_key, private_key) = rsa.newkeys(512) # $ PublicKeyGeneration keySize=512
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(public_key, private_key) = rsa.newkeys(nbits=512) # $ PublicKeyGeneration keySize=512
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# ------------------------------------------------------------------------------
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# encrypt/decrypt
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# ------------------------------------------------------------------------------
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# Note: These are using PKCS#1 v1.5
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print("encrypt/decrypt")
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secret_message = b"secret message"
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encrypted = rsa.encrypt(secret_message, public_key) # $ CryptographicOperation CryptographicOperationAlgorithm=RSA CryptographicOperationInput=secret_message
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encrypted = rsa.encrypt(message=secret_message, pub_key=public_key) # $ CryptographicOperation CryptographicOperationAlgorithm=RSA CryptographicOperationInput=secret_message
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print("encrypted={}".format(encrypted))
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print()
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decrypted = rsa.decrypt(encrypted, private_key) # $ CryptographicOperation CryptographicOperationAlgorithm=RSA CryptographicOperationInput=encrypted
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decrypted = rsa.decrypt(crypto=encrypted, priv_key=private_key) # $ CryptographicOperation CryptographicOperationAlgorithm=RSA CryptographicOperationInput=encrypted
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print("decrypted={}".format(decrypted))
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assert decrypted == secret_message
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print("\n---\n")
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# ------------------------------------------------------------------------------
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# sign/verify
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# ------------------------------------------------------------------------------
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# Note: These are using PKCS#1 v1.5
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print("sign/verify")
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message = b"message"
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other_message = b"other message"
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hash = rsa.compute_hash(message, "SHA-256") # $ CryptographicOperation CryptographicOperationAlgorithm=SHA256 CryptographicOperationInput=message
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hash = rsa.compute_hash(message=message, method_name="SHA-256") # $ CryptographicOperation CryptographicOperationAlgorithm=SHA256 CryptographicOperationInput=message
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signature_from_hash = rsa.sign_hash(hash, private_key, "SHA-256") # $ CryptographicOperation CryptographicOperationAlgorithm=RSA CryptographicOperationInput=hash
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signature_from_hash = rsa.sign_hash(hash_value=hash, priv_key=private_key, hash_method="SHA-256") # $ CryptographicOperation CryptographicOperationAlgorithm=RSA CryptographicOperationInput=hash
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signature = rsa.sign(message, private_key, "SHA-256") # $ CryptographicOperation CryptographicOperationAlgorithm=RSA CryptographicOperationAlgorithm=SHA256 CryptographicOperationInput=message
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signature = rsa.sign(message=message, priv_key=private_key, hash_method="SHA-256") # $ CryptographicOperation CryptographicOperationAlgorithm=RSA CryptographicOperationAlgorithm=SHA256 CryptographicOperationInput=message
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assert signature == signature_from_hash
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print("signature={}".format(signature))
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print()
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rsa.verify(message, signature, public_key) # $ CryptographicOperation CryptographicOperationAlgorithm=RSA CryptographicOperationInput=message CryptographicOperationInput=signature
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rsa.verify(message=message, signature=signature, pub_key=public_key) # $ CryptographicOperation CryptographicOperationAlgorithm=RSA CryptographicOperationInput=message CryptographicOperationInput=signature
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print("Signature verified (as expected)")
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try:
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rsa.verify(other_message, signature, public_key) # $ CryptographicOperation CryptographicOperationAlgorithm=RSA CryptographicOperationInput=other_message CryptographicOperationInput=signature
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raise Exception("Signature verified (unexpected)")
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except rsa.VerificationError:
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print("Signature mismatch (as expected)")

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