kotlin.lang.security.weak-rsa.use-of-weak-rsa-key

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RSA keys should be at least 2048 bits based on NIST recommendation.

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Defintion

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rules:
  - id: use-of-weak-rsa-key
    message: RSA keys should be at least 2048 bits based on NIST recommendation.
    languages:
      - kt
    severity: WARNING
    metadata:
      cwe:
        - "CWE-326: Inadequate Encryption Strength"
      owasp:
        - A03:2017 - Sensitive Data Exposure
        - A02:2021 - Cryptographic Failures
      source-rule-url: https://find-sec-bugs.github.io/bugs.htm#RSA_KEY_SIZE
      asvs:
        section: V6 Stored Cryptography Verification Requirements
        control_id: 6.2.5 Insecure Algorithm
        control_url: https://github.com/OWASP/ASVS/blob/master/4.0/en/0x14-V6-Cryptography.md#v62-algorithms
        version: "4"
      references:
        - https://cheatsheetseries.owasp.org/cheatsheets/Cryptographic_Storage_Cheat_Sheet.html#algorithms
      category: security
      technology:
        - kotlin
      subcategory:
        - audit
      likelihood: HIGH
      impact: MEDIUM
      confidence: HIGH
      license: Commons Clause License Condition v1.0[LGPL-2.1-only]
      vulnerability_class:
        - Cryptographic Issues
    patterns:
      - pattern-either:
          - pattern: |
              $KEY = $G.getInstance("RSA")
              ...
              $KEY.initialize($BITS)
      - metavariable-comparison:
          metavariable: $BITS
          comparison: $BITS < 2048

Examples

weak-rsa.kt

import java.security.KeyPairGenerator

public class WeakRSA {

  fun rsaWeak(): Void {
    // ruleid: use-of-weak-rsa-key
    val keyGen: KeyPairGenerator = KeyPairGenerator.getInstance("RSA")
    keyGen.initialize(512)
  }

  fun rsaOK(): Void {
    // ok: use-of-weak-rsa-key
    val keyGen = KeyPairGenerator.getInstance("RSA");
    keyGen.initialize(2048);
  }
}