> For the complete documentation index, see [llms.txt](https://docs.xrpl-commons.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.xrpl-commons.org/core-dev-bootcamp/module04/appendices/rfcs-and-standards-reference.md). # Appendix : RFCs and Standards Reference ### Introduction This appendix provides references to the cryptographic standards, RFCs, and specifications that XRPL's cryptography is built upon. Understanding these standards helps you understand why rippled makes certain design choices. ### Cryptographic Algorithms #### Ed25519 Digital Signatures **RFC 8032 - Edwards-Curve Digital Signature Algorithm (EdDSA)** * **URL**: * **Published**: January 2017 * **Status**: Proposed Standard **What it defines:** * EdDSA signature scheme using Edwards curves * Ed25519: EdDSA with Curve25519 * Ed448: EdDSA with Ed448-Goldilocks * Test vectors and implementation guidelines **Key parameters (Ed25519):** * Curve: Curve25519 (Edwards form) * Hash function: SHA-512 * Public key size: 32 bytes * Signature size: 64 bytes * Security level: \~128 bits **Why XRPL uses it:** * Fast signature verification (\~5x faster than ECDSA) * Simple implementation * No signature malleability * Modern design with security proofs #### secp256k1 Elliptic Curve **SEC 2: Recommended Elliptic Curve Domain Parameters** * **Publisher**: Standards for Efficient Cryptography Group (SECG) * **URL**: * **Version**: 2.0, January 2010 **What it defines:** * Elliptic curve parameters for secp256k1 * Curve equation: y² = x³ + 7 (mod p) * Prime field size p and generator point G * Compression/decompression of public keys **Key parameters (secp256k1):** ``` p = FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFE FFFFFC2F n = FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFE BAAEDCE6 AF48A03B BFD25E8C D0364141 G = (x, y) where: x = 79BE667E F9DCBBAC 55A06295 CE870B07 029BFCDB 2DCE28D9 59F2815B 16F81798 y = 483ADA77 26A3C465 5DA4FBFC 0E1108A8 FD17B448 A6855419 9C47D08F FB10D4B8 ``` **Why XRPL uses it:** * Ecosystem compatibility * Well-tested (used since 2009) * Supported by many libraries and tools #### ECDSA Signatures **FIPS 186-4 - Digital Signature Standard (DSS)** * **Publisher**: NIST * **URL**: * **Published**: July 2013 **What it defines:** * ECDSA signature algorithm * Key generation procedures * Signature generation and verification * Approved curves (including secp256k1) #### Deterministic ECDSA Nonces **RFC 6979 - Deterministic Usage of DSA and ECDSA** * **URL**: * **Published**: August 2013 * **Status**: Informational **What it defines:** * Deterministic nonce generation for ECDSA * Eliminates need for secure random number generation during signing * Prevents nonce reuse vulnerabilities **Algorithm:** ``` k = HMAC_DRBG(private_key, message_hash) ``` **Why XRPL uses it:** * Prevents catastrophic nonce reuse * Makes signing deterministic (same message = same signature) * No dependency on RNG quality during signing ### Hash Functions #### SHA-2 Family **FIPS 180-4 - Secure Hash Standard (SHS)** * **Publisher**: NIST * **URL**: * **Published**: August 2015 **What it defines:** * SHA-256: 256-bit hash (32 bytes) * SHA-512: 512-bit hash (64 bytes) * Padding and iteration schemes * Test vectors **XRPL usage:** * SHA-512-Half: First 32 bytes of SHA-512 * SHA-256: Used in Base58Check checksums * Both used in RIPESHA double hash **Why SHA-512-Half:** * Faster on 64-bit CPUs than SHA-256 * Same output size (256 bits) * Same security level #### RIPEMD-160 **Original Paper**: "RIPEMD-160: A Strengthened Version of RIPEMD" * **Authors**: Dobbertin, Bosselaers, Preneel * **Published**: 1996 * **Hash size**: 160 bits (20 bytes) **XRPL usage:** * Second stage of RIPESHA hash * Used in address generation **Algorithm:** ``` RIPESHA(data) = RIPEMD-160(SHA-256(data)) ``` ### Key Derivation #### PBKDF2 **RFC 2898 - PKCS #5: Password-Based Cryptography Specification** * **URL**: * **Published**: September 2000 * **Status**: Informational **What it defines:** * Password-Based Key Derivation Function 2 * Iterated hashing to slow brute-force * Salt for uniqueness **Note:** XRPL doesn't use PBKDF2 for key derivation (uses sha512Half of seed), but it's relevant for password-based seed derivation in wallets. ### Encoding #### Base58 **No formal RFC, but based on:** * Design by Satoshi Nakamoto * Excludes similar-looking characters (0, O, I, l) * Used widely in blockchain systems **Alphabet:** ``` 123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz ``` **XRPL implementation:** * Base58Check with 4-byte SHA-256(SHA-256()) checksum * Type prefix byte determines first character * Compatible with other blockchain systems #### Base64 **RFC 4648 - The Base16, Base32, and Base64 Data Encodings** * **URL**: * **Published**: October 2006 * **Status**: Proposed Standard **XRPL usage:** * Used in peer handshake (Session-Signature header) * Not used for addresses (uses Base58Check instead) ### Transport Security #### TLS 1.2 **RFC 5246 - The Transport Layer Security (TLS) Protocol Version 1.2** * **URL**: * **Published**: August 2008 * **Status**: Proposed Standard **What it defines:** * Handshake protocol * Record protocol * Cipher suites * Certificate verification **XRPL usage:** * Peer-to-peer communication * WebSocket connections * RPC endpoints #### TLS 1.3 **RFC 8446 - The Transport Layer Security (TLS) Protocol Version 1.3** * **URL**: * **Published**: August 2018 * **Status**: Proposed Standard **Improvements over TLS 1.2:** * Faster handshake * Forward secrecy by default * Simplified cipher suite negotiation ### DER Encoding **ITU-T X.690 - ASN.1 encoding rules** * **Publisher**: ITU-T * **Published**: 2015 **What it defines:** * Distinguished Encoding Rules (DER) * Used for secp256k1 signature encoding * Canonical binary format **Structure:** ``` SEQUENCE { r INTEGER, s INTEGER } Encoded as: 0x30 [length] 0x02 [r-length] [r] 0x02 [s-length] [s] ``` ### Random Number Generation **NIST SP 800-90A - Recommendation for Random Number Generation** * **Publisher**: NIST * **URL**: * **Published**: June 2015 **What it defines:** * Deterministic Random Bit Generators (DRBGs) * CTR\_DRBG, HASH\_DRBG, HMAC\_DRBG * Entropy requirements * Testing procedures **XRPL usage:** * Relies on OpenSSL's RAND\_bytes * OpenSSL implements NIST-approved DRBGs ### Mnemonic Words **RFC 1751 - A Convention for Human-Readable 128-bit Keys** * **URL**: * **Published**: December 1994 * **Status**: Informational **What it defines:** * Encoding 128-bit keys as English words * 2048-word dictionary * Checksum embedded in last word **XRPL usage:** * Optional seed encoding format * Alternative to Base58 for seeds * Easier to write down/speak **Example:** ``` Seed (hex): DEDCE9CE67B451D852FD4E846FCDE31C Words: MAD WARM EVEN SHOW BALK FELT TOY STIR OBOE COST HOPE VAIN ``` ### Cryptographic Best Practices **NIST SP 800-57 - Recommendation for Key Management** * **Publisher**: NIST * **URL**: * **Published**: May 2020 **What it defines:** * Key length recommendations * Algorithm lifetime * Key usage guidance * Security strength equivalences **Security Levels:** ``` Bits Symmetric Hash RSA ECC ──────────────────────────────────────────── 128 AES-128 SHA-256 3072 256 192 AES-192 SHA-384 7680 384 256 AES-256 SHA-512 15360 512 ``` **XRPL compliance:** * 256-bit secret keys (ECC) * 256-bit hashes (SHA-512-Half) * \~128-bit security level for Ed25519 * \~128-bit security level for secp256k1 ### Implementation Libraries #### OpenSSL **Website**: \ **License**: Apache License 2.0 **What rippled uses:** * Random number generation (RAND\_bytes) * Hash functions (SHA-256, SHA-512, RIPEMD-160) * SSL/TLS implementation * Some low-level crypto primitives #### secp256k1 **Repository**: \ **License**: MIT **What rippled uses:** * secp256k1 curve operations * ECDSA signing and verification * Public key derivation * Signature parsing/serialization #### ed25519-donna **Repository**: \ **License**: Public Domain **What rippled uses:** * Ed25519 signing and verification * Public key derivation * Fast implementation ### Recommended Reading #### Books 1. **"Serious Cryptography"** by Jean-Philippe Aumasson * Modern cryptography handbook * Practical focus 2. **"Cryptography Engineering"** by Ferguson, Schneier, Kohno * Implementation-focused * Real-world protocols 3. **"Applied Cryptography"** by Bruce Schneier * Classic reference * Comprehensive coverage #### Papers 1. **"A Graduate Course in Applied Cryptography"** by Boneh and Shoup * Free online: * Modern approach 2. **"High-speed high-security signatures"** by Bernstein et al. * Ed25519 design paper * Performance analysis #### Online Resources 1. **Cryptopals Challenges**: * Hands-on crypto exercises * Breaking weak implementations 2. **Crypto101**: * Introductory book * Free online ### Standard Bodies * **IETF**: Internet Engineering Task Force (RFCs) * **NIST**: National Institute of Standards and Technology * **ISO**: International Organization for Standardization * **SECG**: Standards for Efficient Cryptography Group ### Summary Key standards for XRPL cryptography: * **RFC 8032**: Ed25519 signatures * **RFC 6979**: Deterministic ECDSA nonces * **FIPS 180-4**: SHA-2 hash functions * **SEC 2**: secp256k1 curve parameters * **RFC 5246/8446**: TLS for transport security Understanding these standards helps you: * Know why algorithms were chosen * Verify implementations are correct * Stay current with best practices * Contribute improvements