Security Strength

Created OnMarch 5, 2025

Last Updated OnMay 6, 2025

What is Security Strength?

Security strength in cryptography refers to the amount of computational work required to break a particular cryptographic algorithm or system. It’s often expressed in bits, indicating the number of possible key combinations that an attacker would need to test. Higher security strength translates to greater resistance against attacks, including brute-force attempts.

Here’s a bit more detail…

Measuring Strength: This is measured in bits, with higher bit values indicating greater difficulty in breaking the encryption. For example, a 256-bit encryption has 2²⁵⁶ possible key combinations, which is significantly more than the 2¹²⁸ possible combinations of a 128-bit encryption.
Cryptographic Algorithms: This is a crucial factor in choosing the right cryptographic algorithm for protecting data. Algorithms with higher security strength are preferred for protecting sensitive information, like financial data or classified information, against potential threats.
Key Length: The key length of an encryption algorithm directly impacts its strength. For instance, RSA algorithms with larger key sizes (e.g., 2048-bit keys) offer stronger protection against attacks than those with shorter keys.
Impact of Attacks: As computing power advances, the strength of algorithms may need to be increased to stay ahead of potential attackers. This constant evolution in the cryptographic landscape is why there’s a “cryptographic arms race,” where algorithms are constantly being refined and upgraded to withstand new attacks.

Security Strength in Different Contexts: Security strength is not just applicable to encryption; it also applies to other cryptographic functions like digital signatures and hash functions. For example, HMAC algorithms combine a secret key with a cryptographic hash function. This provides data authentication and integrity. Their security strength is determined by both the key length and the hash algorithm used

DEFINITIONS

A measure of the computational complexity associated with recovering certain secret and/or security-critical information concerning a given cryptographic algorithm from known data (e.g. plaintext/ciphertext pairs for a given encryption algorithm).
SOURCE: SP 800-108

A number associated with the amount of work (that is, the number of operations) that is required to break a cryptographic algorithm or system. Sometimes referred to as a security level.
SOURCE: FIPS 186

See various NIST definitions

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