# Fully Annotated Citations

## Smart Signatures

### Allen Smart Signatures 2015

* _**Smart Signatures**_ (2015). [white paper]. _Allen, Christopher; Maxwell, Greg; Todd, Peter; Shea, Ryan; Wuille, Pieter; Bonneau, Joseph; Poon, Joseph; Close, Tyler._ Produced as part of _"Rebooting Web of Trust Workshop"_, November 3-4, 2015, San Francisco, CA. Version 1.0.1. Retrieved 2024-12-12 from GitHub/WebOfTrustInfo [PDF]: <https://github.com/WebOfTrustInfo/rwot1-sf/blob/master/final-documents/smart-signatures.pdf>.

> **TAGS**: #SmartSignatures #CryptographicSignatures #BitcoinScripting #DecentralizedTrust #DigitalIdentity #AuthorizationSystems #SelfSovereignIdentity #Multisig #Blockchain #WebOfTrust

> **SHORT ABSTRACT**: "This white paper introduces 'Smart Signatures,' an evolution of cryptographic signatures that allow dynamic, programmable verification conditions beyond traditional key-based systems. Inspired by Bitcoin's scripting language, the paper outlines applications ranging from short-term delegation to complex financial contracts, proposing a flexible authorization model suitable for decentralized ecosystems."

> **KEY POINTS**:
> - **Bitcoin Scripting as Foundation**: Smart Signatures build upon Bitcoin's script-based transaction authorization, enabling programmable conditions for access.
> - **Dynamic Authorization**: Introduces the concept of embedding scripts within certificates to define custom verification rules, allowing for unprecedented flexibility in authorization mechanisms.
> - **Support for Delegation**: Supports various delegation models, including short-term, limited, and complex delegation, enhancing usability across diverse scenarios.
> - **Increased Extensibility**: The proposed system allows for new operations and features, fostering adaptability to future use cases.
> - **Enhanced Privacy via Pruning**: Incorporates techniques like pruning unused script branches to improve privacy in verification processes.
> - **Support for Complex Logic**: Enables sophisticated multisig setups and hierarchical delegation through Merkelized Abstract Syntax Trees (MAST).
> - **Potential Applications**: Envisions use cases like temporary key delegation, role-specific authentication, and conditional access control in both digital and financial ecosystems.
> - **Implementation Challenges**: Discusses open questions like static versus run-time context, oracle integration, and revocation mechanisms.
> - **Vision for Trust Models**: Aligns with existing trust paradigms (CA, PGP, etc.) while extending capabilities for emerging decentralized trust systems.
> - **Future Development Path**: Highlights the need for proof-of-concept prototypes and advancements in scripting languages to realize the system's full potential.

> **KEY QUOTES**:
> - "Embedding the script inside the certificate ensures that the same method is used to evaluate it on all devices." (Page 4)
> - "The largest benefit of explicit specification of authorization conditions is that the system is fully extensible, so new operations can be defined at any time." (Page 2)
> - "Pruning unused branches of the MAST can significantly improve privacy while maintaining verifiable authenticity." (Page 5)
> - "At minimum smart signatures should support existing trust models, including self-signed certificates, CA-style certificates, and PGP-style key validation." (Page 4)
> - "Short-lived keys and their integration into hierarchical deterministic (HD) setups could revolutionize approaches to key management." (Page 6)
> - "Static and dynamic contexts within the virtual machine may dictate the feasibility and complexity of many proposed use cases." (Page 6)
> - "Delegation mechanisms must balance functionality and security, particularly in scenarios requiring partial or temporary authority sharing." (Page 5)
> - "Future upgrades to scripting languages must retain simplicity while enabling the advanced capabilities envisioned for smart signatures." (Page 6)

### Allen Smarter Signatures 2016

* _**Smarter Signatures: Experiments in Verifications**_ (2024). [web article]. _Allen, Christopher; Appelcline, Shannon._ Retrieved 2024-12-12 from Life With Alacrity: <https://www.lifewithalacrity.com/article/smarter-signatures-experiments-in-verifications/>. Originally produced as part of _"Rebooting Web of Trust Workshop_II (ID2020)"_, May 21-22, 2016, New York, NY. Version 1.0.1 10-18-16. Retrieved 2024-12-12 from GitHub/WebOfTrustInfo [PDF](https://github.com/WebOfTrustInfo/rwot2-id2020/blob/master/final-documents/smarter-signatures.pdf)

> **TAGS**: #DigitalSignatures #SmartSignatures #VerificationSystems #DigitalIdentity #Cryptography #DecentralizedVerification #DigitalSecurity #BlockchainInnovation

> **SHORT ABSTRACT**: "This article introduces the concept of 'smart signatures,' a transformative evolution of traditional digital signatures. By integrating business logic directly into the signature process, the authors propose a flexible framework that accommodates complex verification needs in modern digital systems, balancing security, flexibility, and privacy."

> **KEY POINTS**:
> - **Traditional Digital Signatures**: Highlights limitations of standard cryptographic identity verification methods.
> - **Introduction of Multisignatures**: Explains how Bitcoin's multisignature transactions provided partial solutions but lacked sufficient flexibility.
> - **Smart Signatures Defined**: Introduces the idea of integrating conditions and business logic directly into the signature mechanism.
> - **Requirements for Smart Signatures**: Lists six essential criteria, including determinism, composability, and minimal computational overhead.
> - **Use Cases**: Describes applications such as conditional approvals, time-based constraints, and multi-party authorizations.
> - **Balance of Privacy and Complexity**: Discusses the trade-offs between functionality and the need to protect participants’ privacy.
> - **Programming Paradigms**: Evaluates functional programming and deterministic predicates for implementing smart signatures.
> - **Real-World Examples**: Analyzes existing systems like Bitcoin Script and innovative models like Peter Todd's Dex.
> - **Future Directions**: Calls for extensive experimentation and rigorous design to establish reliable systems.

> **KEY QUOTES**:
> - "Smart signatures represent a pivotal shift, embedding logic and conditions into the core of digital verification processes."
> - "The balance between security and usability is delicate—too much flexibility can compromise privacy, while rigid systems cannot adapt to complex scenarios."
> - "By leveraging deterministic systems and composable functions, we can ensure that smart signatures meet the demands of modern cryptographic ecosystems."
> - "Bitcoin's introduction of multisignatures was revolutionary, but the needs of today demand a more nuanced and dynamic approach."
> - "Integrating business logic directly into digital signatures opens the door to endless possibilities, from conditional contracts to multi-party approvals."
> - "Privacy concerns are not an afterthought but a fundamental component of the design process for any smart signature system."
> - "The complexity of modern verification systems underscores the need for simplicity and clarity in their underlying implementations."
> - "The lessons from failures like the DAO underscore the importance of rigorous design and testing in advancing cryptographic solutions."
> - "The future of digital verification lies not in static solutions but in dynamic systems that can evolve with the challenges they face."

## Allen Smart Signatures Video 2016
* _**Smart Signatures: Experiments in Authorization**_ (2016-06-29). [YouTube video; transcript]. _Allen, Christopher._ Originally presented at the W3C Blockchain Workshop 2016. Video available on YouTube: <https://www.youtube.com/watch?v=E9sbWKbfyJU>. Transcript available from BTC Transcripts: <https://btctranscripts.com/w3-blockchain-workshop-2016/smart-signatures>, PDF of presentation

> **TAGS**: #SmartSignatures #DigitalAuthorization #BlockchainSecurity #DecentralizedVerification #ComposableProofs #DigitalSignatures #CryptographicAdvancements #AuthorizationModels

> **SHORT ABSTRACT**: "This presentation introduces the concept of 'smart signatures,' a transformative evolution of traditional digital signatures. By integrating business logic directly into the signature process, the authors propose a flexible framework that accommodates complex verification needs in modern digital systems, balancing security, flexibility, and privacy. Christopher Allen outlines the technical and practical aspects of these signatures, emphasizing their potential to enhance authorization systems."

> **KEY POINTS**:
> - **Definition of Digital Signatures**: A digital signature is defined as "a hash of an object encrypted by a private key and verified by a public key."
> - **Introduction of Smart Signatures**: Proposes extending traditional digital signatures with features like multi-signature capabilities (e.g., M-of-N schemes).
> - **Use Cases for Smart Signatures**: Includes time-limited delegation and value-based transaction restrictions.
> - **Six Requirements**: Composability (building from simple operations), Provability (logical analysis), Determinism (consistent behavior), Efficiency (low overhead), Boundedness (resource limits), Inspectability (human readability).
> - **Support for Multiple Cryptographic Algorithms**: Highlights compatibility with ECDSA, RSA, and quantum-resistant options like sphinx hash signatures.
> - **Revocation and Context Challenges**: Discusses the difficulties in defining contexts and implementing revocation mechanisms.
> - **Role of Oracles**: Identifies the need for external oracles to provide trusted data in certain smart signature scenarios.
> - **Hardware Integration**: Explores how hardware-based solutions could improve the security of smart signatures.

> **KEY QUOTES**:
> - "A digital signature is a hash of an object that has been encrypted by a private key and verified by a public key."
> - "Smart signatures introduce flexibility, allowing for time-limited delegation and value-based restrictions."
> - "The inspectability and provability of smart signatures are essential for their adoption in decentralized systems."
> - "One of the biggest challenges in implementing smart signatures is defining the context in which they operate."
> - "Oracles will play a critical role in expanding the functionality of smart signatures by providing external, trusted data."
> - "With smart signatures, we can embed conditions directly into the cryptographic process, creating a more dynamic authorization model."
> - "The ability to revoke or update a signature in response to new information is critical in certain use cases."
> - "Hardware-backed solutions can add an extra layer of security, particularly for high-value transactions or sensitive operations."
> - "Smart signatures enable decentralized systems to move beyond static verification methods to a more adaptable framework."
> - "As we build more sophisticated systems, ensuring deterministic and bounded computation will remain a cornerstone of security."

## Schnorr

#### [^Allen-Schnorr-Intro-2023]

* _**A Layperson’s Intro to Schnorr**_ (2023-10-24). [web article]. _Allen, Christopher._ Retrieved 2024-12-12 from Blockchain Commons: <https://www.BlockchainCommons.com/musings/Schnorr-Intro/>. Cross-posted at Life With Alacrity: <https://www.LifeWithAlacrity.com/article/musings-schnorr/>.

> **TAGS**: #SchnorrSignatures #DigitalSignatures #Cryptography #SignatureAggregation #ThresholdSignatures #BlindSignatures #AdapterSignatures #FiniteFields #EllipticCurveCryptography #Bitcoin

> **SHORT ABSTRACT**: "This article provides an accessible introduction to Schnorr signatures, highlighting their compactness, efficiency, and advanced cryptographic capabilities such as signature aggregation, threshold signatures, and blind signatures. It also delves into the mathematical foundations underpinning Schnorr signatures, including finite fields and elliptic curve cryptography."

> **KEY POINTS**:
> - **Compactness**: Schnorr signatures are small, even when there are multiple signers.
> - **Signature Aggregation**: Multiple signatures can be aggregated together and look exactly like a single signature.
> - **Faster Verification**: Due to their small size and aggregation capabilities, Schnorr signatures can be verified quickly.
> - **Threshold Signatures**: Multisignatures requiring a certain quorum of participants are possible.
> - **Blind Signatures**: Signatures can be made while hiding the content.
> - **Adapter Signatures**: Signatures can be hidden by other values.
> - **Mathematical Foundation**: Schnorr signatures depend on finite field math and elliptic curves, such as Bitcoin’s `secp256k1`.
> - **Schnorr in a Nutshell (8 Bits)**: Uses simple math in a relatable 8-bit context to explain Schnorr's compactness, aggregation, and verification.

> **KEY QUOTES**:
> - "Schnorr signatures have been a long time coming, but now that they’re finally here, they open up broad new cryptographic frontiers..."
> - "I discovered RSA, which secures its signatures using prime numbers, in college. But it was when I later encountered Schnorr, built on finite fields, that I met the first cryptography that I truly fell in love with."
> - "Beyond all of their new benefits, I fell in love with Schnorr signatures because they were elegant."
> - "The aggregation of signatures was done with simple mathematical operations. You added two signatures together and they were aggregated!"
> - "Think of finite fields as domains where numbers play by a unique set of rules."
> - "Schnorr in 8 Bits: Add up 2 + 3, modulo 7 (5). It's the simplicity and elegance of modular arithmetic that powers Schnorr's capabilities."
> - "Schnorr’s aggregation capabilities could redefine the scalability of blockchain systems by significantly reducing the size of transactions."