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Cryptology Academy · Lesson

ECC vs RSA: Security & Performance Trade-offs

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

Lesson 4 of 413 steps

ECC vs RSA: Security & Performance Trade-offs is a free Cryptology Academy lesson on CoddyKit. This is 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, and your progress syncs across the web and the CoddyKit app. The Cryptology Academy course includes 4 lessons in total.

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?
Answer it in the interactive lesson

Recap

ECC dominates RSA in every practical dimension except RSA's faster verification. Next we master MACs and HMAC construction.
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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. 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. The Cryptology Academy course includes 4 lessons in total.

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, so you can start here or from the beginning and move at your own pace. This is lesson 4 of 4.

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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