Library
Where this content comes from — and where to go deeper
Every module on this site is written from the official standards, RFCs, and original papers that actually define these algorithms. Worked examples (like the toy RSA and Diffie-Hellman key pairs) are computed directly from those specifications, not copied from a textbook.
Alongside those primary sources, this library also collects the sites, blogs, courses, and books worth reading once a module raises more questions than it answers — search or filter by type to find either.
The explanatory text itself was drafted with Claude (Anthropic), synthesizing the sources below rather than quoting them, and reviewed for technical accuracy during writing. If you spot something that doesn't match the underlying spec, treat the spec as authoritative — and consider it a bug in this site worth reporting.
67 of 67 entries
- Foundational papersFoundational papersCommunication Theory of Secrecy Systems ↗
C. E. Shannon, Bell System Technical Journal, 1949
The paper that put cryptography on a mathematical footing, and proved the one-time pad achieves perfect secrecy.
- Foundational papersFoundational papersNew Directions in Cryptography ↗
W. Diffie & M. Hellman, IEEE Transactions on Information Theory, 1976
The original public-key key-exchange paper.
- Foundational papersFoundational papersA Method for Obtaining Digital Signatures and Public-Key Cryptosystems ↗
R. Rivest, A. Shamir, L. Adleman, Communications of the ACM, 1978
The original RSA paper.
- Foundational papersFoundational papersA Public Key Cryptosystem and a Signature Scheme Based on Discrete Logarithms ↗
T. ElGamal, IEEE Transactions on Information Theory, 1985
The original ElGamal encryption and signature paper.
- Foundational papersFoundational papersAlgorithms for Quantum Computation: Discrete Logarithms and Factoring ↗
P. W. Shor, Proceedings of the 35th Annual Symposium on Foundations of Computer Science, 1994
The paper behind the entire post-quantum migration this site is framed around.
- Standards & RFCsSymmetric-key cryptographyFIPS 197 — Advanced Encryption Standard (AES) ↗
NIST
- Standards & RFCsSymmetric-key cryptographyFIPS 46-3 — Data Encryption Standard (DES) ↗
NIST
Withdrawn in 2005 once its 56-bit key became exhaustively searchable; superseded by AES.
- Standards & RFCsSymmetric-key cryptographySP 800-38D — Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC ↗
NIST
- Standards & RFCsSymmetric-key cryptographyRFC 8439 — ChaCha20 and Poly1305 for IETF Protocols ↗
IETF
- Standards & RFCsPublic-key cryptography (RSA, Diffie-Hellman, ElGamal, ECC)FIPS 186-5 — Digital Signature Standard (DSS) ↗
NIST
Covers RSA and ECDSA signature parameters.
- Standards & RFCsPublic-key cryptography (RSA, Diffie-Hellman, ElGamal, ECC)RFC 8017 — PKCS #1: RSA Cryptography Specifications Version 2.2 ↗
IETF
OAEP and PKCS#1 v1.5 padding.
- Standards & RFCsPublic-key cryptography (RSA, Diffie-Hellman, ElGamal, ECC)SP 800-56A Rev. 3 — Recommendation for Pair-Wise Key-Establishment Using Discrete Logarithm Cryptography ↗
NIST
Covers Diffie-Hellman and ECDH.
- Standards & RFCsPublic-key cryptography (RSA, Diffie-Hellman, ElGamal, ECC)SP 800-186 — Recommendations for Discrete Logarithm-based Cryptography: Elliptic Curve Domain Parameters ↗
NIST
- Standards & RFCsHashing, signatures & key derivationFIPS 180-4 — Secure Hash Standard (SHS) ↗
NIST
SHA-2 family.
- Standards & RFCsHashing, signatures & key derivationFIPS 202 — SHA-3 Standard ↗
NIST
- Standards & RFCsHashing, signatures & key derivationRFC 2104 — HMAC: Keyed-Hashing for Message Authentication ↗
IETF
- Standards & RFCsHashing, signatures & key derivationRFC 8018 — PKCS #5: Password-Based Cryptography Specification Version 2.1 ↗
IETF
PBKDF2.
- Standards & RFCsHashing, signatures & key derivationRFC 9106 — Argon2 Memory-Hard Function for Password Hashing and Proof-of-Work Applications ↗
IETF / IRTF CFRG
- Standards & RFCsProtocols (TLS, certificates, JWT, SSH, Signal, WebAuthn)RFC 9846 — The Transport Layer Security (TLS) Protocol Version 1.3 ↗
IETF
- Standards & RFCsProtocols (TLS, certificates, JWT, SSH, Signal, WebAuthn)RFC 5280 — Internet X.509 Public Key Infrastructure Certificate and CRL Profile ↗
IETF
- Standards & RFCsProtocols (TLS, certificates, JWT, SSH, Signal, WebAuthn)RFC 6960 — X.509 Internet PKI Online Certificate Status Protocol (OCSP) ↗
IETF
- Standards & RFCsProtocols (TLS, certificates, JWT, SSH, Signal, WebAuthn)RFC 9162 — Certificate Transparency Version 2.0 ↗
IETF
- Standards & RFCsProtocols (TLS, certificates, JWT, SSH, Signal, WebAuthn)RFC 7519 — JSON Web Token (JWT) ↗
IETF
- Standards & RFCsProtocols (TLS, certificates, JWT, SSH, Signal, WebAuthn)RFC 7515 — JSON Web Signature (JWS) ↗
IETF
- Standards & RFCsProtocols (TLS, certificates, JWT, SSH, Signal, WebAuthn)RFC 4251 — The Secure Shell (SSH) Protocol Architecture ↗
IETF
- Standards & RFCsProtocols (TLS, certificates, JWT, SSH, Signal, WebAuthn)The X3DH Key Agreement Protocol ↗
Signal
- Standards & RFCsProtocols (TLS, certificates, JWT, SSH, Signal, WebAuthn)The Double Ratchet Algorithm ↗
Signal
- Standards & RFCsProtocols (TLS, certificates, JWT, SSH, Signal, WebAuthn)Web Authentication: An API for accessing Public Key Credentials — Level 3 ↗
W3C Recommendation
The WebAuthn standard passkeys are built on.
- Standards & RFCsKey management, PKI automation & federated identityRFC 3394 — Advanced Encryption Standard (AES) Key Wrap Algorithm ↗
IETF
- Standards & RFCsKey management, PKI automation & federated identityRFC 8555 — Automatic Certificate Management Environment (ACME) ↗
IETF
The protocol behind Let's Encrypt and automated certificate issuance.
- Standards & RFCsKey management, PKI automation & federated identityRFC 7636 — Proof Key for Code Exchange by OAuth Public Clients (PKCE) ↗
IETF
- Standards & RFCsKey management, PKI automation & federated identityOpenID Connect Core 1.0 ↗
OpenID Foundation
- Standards & RFCsKey management, PKI automation & federated identityAssertions and Protocols for the OASIS Security Assertion Markup Language (SAML) V2.0 ↗
OASIS Standard
- Standards & RFCsKey management, PKI automation & federated identityPKCS #11 Cryptographic Token Interface Base Specification Version 3.0 ↗
OASIS Standard
The current Cryptoki specification: the object model, attributes (CKA_SENSITIVE, CKA_EXTRACTABLE), and the full function list this site's PKCS#11 use case and Playground tool are built from.
- Standards & RFCsKey management, PKI automation & federated identityRFC 5958 — Asymmetric Key Packages (PKCS #8) ↗
IETF
- Standards & RFCsKey management, PKI automation & federated identityRFC 7292 — PKCS #12: Personal Information Exchange Syntax v1.1 ↗
IETF
- Standards & RFCsPost-quantum cryptography & the quantum threatFIPS 203 — Module-Lattice-Based Key-Encapsulation Mechanism Standard (ML-KEM) ↗
NIST
- Standards & RFCsPost-quantum cryptography & the quantum threatFIPS 204 — Module-Lattice-Based Digital Signature Standard (ML-DSA) ↗
NIST
- Standards & RFCsPost-quantum cryptography & the quantum threatFIPS 205 — Stateless Hash-Based Digital Signature Standard (SLH-DSA) ↗
NIST
- Standards & RFCsPost-quantum cryptography & the quantum threatSP 800-57 Part 1 Rev. 5 — Recommendation for Key Management ↗
NIST
Source of the key-size/security-level equivalence table used in this catalog.
- Standards & RFCsStandardization bodiesNIST Computer Security Resource Center ↗
NIST
Home of every FIPS and SP 800 document cited throughout this library.
- Standards & RFCsStandardization bodiesIETF ↗
Internet Engineering Task Force
Home of the RFC series and its working groups.
- Standards & RFCsStandardization bodiesRFC 2119 — Key words for use in RFCs to Indicate Requirement Levels ↗
IETF
Defines what MUST, SHOULD, and MAY mean inside every other RFC that uses them.
- Standards & RFCsStandardization bodiesISO ↗
International Organization for Standardization
Publishes ISO/IEC 27001, 18033, 19790, and the rest of the JTC 1/SC 27 security series jointly with the IEC.
- Standards & RFCsStandardization bodiesOASIS Open ↗
OASIS
Home of SAML 2.0, PKCS#11, and KMIP.
- Sites & practiceFurther hands-on practiceCryptoHack ↗
CryptoHack
A categorized library of cryptography challenges, from classical ciphers through elliptic curves and real-world protocol flaws.
- Sites & practiceFurther hands-on practiceCryptopals Crypto Challenges ↗
Cryptopals
A structured set of exercises, organized into progressive sets, that build real attacks against AES, RSA, Diffie-Hellman, and more from scratch.
- Sites & practiceSites & blogsSchneier on Security ↗
Bruce Schneier
Long-running blog on crypto policy, applied security, and the occasional deep dive into a broken protocol.
- Sites & practiceSites & blogsA Few Thoughts on Cryptographic Engineering ↗
Matthew Green
A Johns Hopkins cryptographer writing accessibly about TLS, protocol security, and why real-world crypto keeps breaking.
- Sites & practiceSites & blogscr.yp.to ↗
Daniel J. Bernstein
The designer of ChaCha20 and Curve25519, writing directly about the algorithms covered in this catalog.
- Sites & practiceSites & blogsIACR ePrint Archive ↗
International Association for Cryptologic Research
The preprint server where new cryptography research — including attacks on things covered here — appears first.
- Sites & practiceSites & blogsReal World Crypto ↗
IACR
An annual conference bridging cryptography research and real deployments — talks and proceedings are free.
- Sites & practiceSites & blogsCryptography I ↗
Dan Boneh, Stanford (Coursera)
The standard free introductory cryptography course — covers the same primitives this site does, with formal rigor.
- Sites & practiceSites & blogsMIT OpenCourseWare — Mathematics & EECS ↗
MIT
Free lecture notes and problem sets from MIT's cryptography and number theory courses.
- Sites & practiceSites & blogsCryptography Stack Exchange ↗
Stack Exchange community
A Q&A site where working cryptographers answer specific, technical questions — good for when a module raises more questions than it answers.
- Sites & practiceSites & blogsCrypTool ↗
CrypTool project
Open-source, interactive software for experimenting with classical and modern ciphers and cryptanalysis techniques.
- Sites & practiceSites & blogsNIST Cryptographic Standards and Guidelines ↗
NIST
The official hub for the FIPS and Special Publications this library cites throughout.
- BooksBooksApplied Cryptography ↗
Bruce Schneier
The classic reference on cryptographic protocols, algorithms, and source code — dated in places, foundational everywhere else.
- BooksBooksSerious Cryptography ↗
Jean-Philippe Aumasson
A practical, modern guide to encryption — symmetric, asymmetric, and the protocols built from them.
- BooksBooksReal-World Cryptography ↗
David Wong
A hands-on guide to the cryptographic primitives and protocols actually deployed today, not just the textbook versions.
- BooksBooksCryptography Engineering ↗
Niels Ferguson, Bruce Schneier & Tadayoshi Kohno
Design principles and hard-won practical guidance for building cryptographic systems that survive contact with reality.
- BooksBooksUnderstanding Cryptography ↗
Christof Paar & Jan Pelzl
A textbook covering essentially the same algorithm set as this site — AES, RSA, ECC, hashing — with more mathematical depth.
- BooksBooksA Graduate Course in Applied Cryptography ↗
Dan Boneh & Victor Shoup
Comprehensive, rigorous, and free — covers private-key encryption, public-key encryption, and digital signatures in full.
- BooksBooksThe Code Book ↗
Simon Singh
The most accessible history of cryptography available — from the scytale to the Enigma to modern public-key cryptography.
- BooksBooksThe Codebreakers ↗
David Kahn
The definitive, exhaustive history of cryptography up to its 1967 publication — the book that founded the field of crypto history.