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Calcimator

Elliptic Curve Cryptography Calculator

Calculate ECC key strength, equivalent RSA key length, security level, and cryptographic parameters.

Inputs

bits

Results

Key Length

256 bits

Equivalent RSA Key Length

512 bits

Security Level

128 bits

Size Advantage over RSA

2×

Brute Force Time10,782,900,000,000,000,000 years
How to Use This Calculator
  1. Select the elliptic curve (P-256, P-384, P-521, Curve25519).
  2. Enter the private key value for computation.
  3. Review the public key point coordinates and equivalent symmetric security level.
  4. Compare the bit-equivalent security to RSA key lengths for the same protection level.
  5. Use NIST P-256 or Curve25519 for most applications -- they offer 128-bit equivalent security.

How the result changes with Custom Key Length

Custom Key LengthKey LengthEquivalent RSA Key LengthSecurity Level
102102 bits204 bits51 bits
358358 bits716 bits179 bits
666666 bits1,332 bits333 bits
922922 bits1,844 bits461 bits

What each input means

Curve Type
Elliptic curve standard
Custom Key Length
Custom key length (0 = use curve default)

How this is calculated

Formula

ECC Security ≈ Key Length / 2

Worked example, using the default values

  1. Identify Input Parameters
    Curve Type = 0, Custom Key Length = 256 = 2 input(s) provided
  2. Calculate Key Length
    256 = 256
  3. Calculate Equivalent RSA Key Length
    Equivalent RSA Key Length
    512 = 512
  4. Calculate Security Level
    Security Level
    128 = 128
  5. Calculate Brute Force Time
    Brute Force Time
    10782900000000000000 = 10782900000000000000

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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