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Cryptology Academy · Lesson

ECC vs RSA: Security & Performance Trade-offs

Compare key sizes, operation speed, and security levels across algorithms.

ECC vs RSA: Security & Performance Trade-offs is a free Cryptology Academy lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Cryptology Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Welcome

ECC and RSA are both used for public-key cryptography. In this lesson we compare them systematically across key size, speed, signature size, and quantum resistance.

Security Level Comparison

Security level | RSA key | ECC key 80-bit | 1024 | 160 112-bit | 2048 | 224 128-bit | 3072 | 256 192-bit | 7680 | 384 256-bit | 15360 | 521 ECC requires ~6-10× smaller keys for equal security.

Key Generation Speed

RSA-2048 key generation: ~50ms (must find two large primes). ECDSA-256 key generation: <1ms (just pick a random scalar). ECC key generation is orders of magnitude faster — important for ephemeral keys.

Signing Speed

ECDSA-256 sign: ~0.05ms. RSA-2048 sign: ~1ms. ECDSA is ~20× faster for signing. Ed25519 sign: ~0.02ms — the fastest signature scheme available.

Verification Speed

RSA-2048 verify: ~0.05ms (cheap — public key operation). ECDSA-256 verify: ~0.2ms. RSA verification is actually faster than ECDSA. Ed25519 batch verification is extremely fast.

Key and Signature Sizes

Algorithm | Key size | Signature size RSA-2048 | 256 B | 256 B RSA-3072 | 384 B | 384 B ECDSA-256 | 64 B | ~71 B (DER) Ed25519 | 32 B | 64 B ECC wins decisively on size.

TLS Handshake Size Impact

TLS certificate with RSA-2048: ~800 bytes. With ECDSA-256: ~300 bytes. Over millions of TLS handshakes per day, this adds up to significant bandwidth savings.

Hardware Acceleration

Intel/AMD CPUs have AES-NI but NO native RSA/ECC instructions. ECDSA on modern CPUs: ~2500 verifications/sec (P-256 software). With dedicated crypto ASICs (HSMs): 100,000+/sec.

Quantum Resistance

Both RSA and ECC are broken by Shor's algorithm on a sufficiently large quantum computer. RSA requires factoring (polynomial in qubit count); ECDLP requires quantum discrete log. Neither survives a cryptographically relevant QC.

Post-Quantum Replacement

NIST PQC standards (2024): CRYSTALS-Kyber (KEM, replacing DH/ECDH), CRYSTALS-Dilithium/Falcon (signatures, replacing RSA/ECDSA). Both RSA and ECC will eventually be replaced.

Hybrid Deployments Today

Current recommendation: deploy ECDSA/ECDH now (performance), plan PQC migration. TLS 1.3 supports hybrid KEM: X25519 + Kyber simultaneously. Both must be broken for compromise.

Quick Check

Approximately how many bits of ECC key are equivalent in security to an RSA-3072 key?

Recap

ECC dominates RSA in every practical dimension except RSA's faster verification. Next we master MACs and HMAC construction.

Frequently asked questions

Is the “ECC vs RSA: Security & Performance Trade-offs” lesson free?

Yes — the full text of “ECC vs RSA: Security & Performance Trade-offs” is free to read here on the web, and the Cryptology Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Cryptology Academy course, upgrade to CoddyKit PRO.

What will I learn in “ECC vs RSA: Security & Performance Trade-offs”?

Compare key sizes, operation speed, and security levels across algorithms. You practise Cryptology Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Cryptology Academy?

No prior experience is required. Cryptology Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “ECC vs RSA: Security & Performance Trade-offs” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Cryptology Academy lesson?

Yes. Every Cryptology Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

  1. Elliptic Curve Group Law
  2. Scalar Multiplication & the ECDLP
  3. Standard Curves: P-256, Curve25519, secp256k1
  4. ECC vs RSA: Security & Performance Trade-offs
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