---
title: kSecAttrEffectiveKeySize
framework: security
role: symbol
role_heading: Global Variable
path: security/ksecattreffectivekeysize
---

# kSecAttrEffectiveKeySize

A key whose value indicates the effective number of bits in a cryptographic key.

## Declaration

```swift
let kSecAttrEffectiveKeySize: CFString
```

## Discussion

Discussion The corresponding value is of type CFNumber and indicates the effective number of bits in this cryptographic key. For example, a DES key has a kSecAttrKeySizeInBits of 64, but a kSecAttrEffectiveKeySize of 56 bits.