Weak Encryption: Insufficient Key Size

ABSTRACT

另外，當使用密鑰大小較小時，強大的加密算法便容易受到強力攻擊。

EXPLANATION

當前的密碼指南建議，RSA 算法使用的密鑰長度至少應為 1024 位。然而，計算能力的提高與因子分解技術[1] 的進步正在挑戰 1024 位 RSA 加密的安全性。

例 1： 以下代碼可生成 512 位 RSA 加密密鑰。

EVP_PKEY * get_RSA_key() {
unsigned long err;
EVP_PKEY * pkey;
RSA * rsa;
rsa = RSA_generate_key(512, 35, NULL, NULL);
if (rsa == NULL) {
err = ERR_get_error();
printf("Error = %s\n",ERR_reason_error_string(err));
return NULL;
    }
pkey = EVP_PKEY_new();
EVP_PKEY_assign_RSA(pkey, rsa);
return pkey;
  }

對于對稱加密，密鑰長度必須至少為 128 位。

REFERENCES

[1] J. Cheng 307-digit key crack endangers 1024-bit RSA

[2] Standards Mapping - OWASP Top 10 2010 - (OWASP 2010) A7 Insecure Cryptographic Storage

[3] Standards Mapping - OWASP Top 10 2007 - (OWASP 2007) A8 Insecure Cryptographic Storage

[4] Standards Mapping - OWASP Top 10 2004 - (OWASP 2004) A8 Insecure Storage

[5] Standards Mapping - Security Technical Implementation Guide Version 3 - (STIG 3) APP3150.1 CAT II

[6] Standards Mapping - Security Technical Implementation Guide Version 3.4 - (STIG 3.4) APP3150.1 CAT II

[7] B. Chess and J. West, Secure Programming with Static Analysis.Boston, MA:Addison-Wesley, 2007.

[8] Cryptographic Algorithms and Key Sizes for Personal Identity Verification NIST

[9] Standards Mapping - Common Weakness Enumeration - (CWE) CWE ID 310

[10] Standards Mapping - Web Application Security Consortium 24 + 2 - (WASC 24 + 2) Information Leakage

[11] Standards Mapping - FIPS200 - (FISMA) MP

[12] Standards Mapping - Payment Card Industry Data Security Standard Version 1.2 - (PCI 1.2) Requirement 3.6.1, Requirement 6.3.1.3, Requirement 6.5.8

[13] Standards Mapping - Payment Card Industry Data Security Standard Version 2.0 - (PCI 2.0) Requirement 3.6.1, Requirement 6.5.3

[14] Standards Mapping - Payment Card Industry Data Security Standard Version 1.1 - (PCI 1.1) Requirement 3.6.1, Requirement 6.5.8

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