> For the complete documentation index, see [llms.txt](https://blockgram.gitbook.io/blockgram-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://blockgram.gitbook.io/blockgram-docs/technical-architecture/security-layer.md).

# Security Layer

#### Encryption Standards and Key Management

BlockGram employs a robust cryptographic framework to ensure confidentiality, integrity, and authenticity of all user data and transactions:

* **Symmetric Encryption:**
  * Uses **AES-256** (Advanced Encryption Standard with 256-bit keys) for encrypting sensitive data at rest and in transit, including private keys stored on user devices or backend infrastructure.
* **Asymmetric Encryption:**
  * Implements **RSA** with 2048+ bit keys for secure key exchange and digital signatures during communication setup and identity verification.
  * Utilizes **Elliptic Curve Cryptography (ECC)**, specifically **secp256k1** curve, aligning with blockchain standards (e.g., Bitcoin, Ethereum) for signing transactions and wallet keys, offering strong security with smaller key sizes and faster computation.
* **Key Management:**
  * Private keys are never stored in plaintext outside secure environments.
  * Hardware Security Modules (HSMs) safeguard server-side keys with controlled access and tamper resistance.
  * User keys leverage platform-secure enclaves (e.g., Apple Secure Enclave, Android Keystore) ensuring local cryptographic operations are isolated from untrusted software.
  * Regular key rotation policies and multi-factor authentication govern administrative access.

#### Zero-Knowledge Proof (zk-SNARK) Implementation for Privacy

* BlockGram integrates **zk-SNARKs (Zero-Knowledge Succinct Non-Interactive Arguments of Knowledge)** to enable privacy-preserving transactions on supported chains:
  * Users can prove ownership of funds or compliance with conditions (e.g., bill split settlements) without revealing transaction details such as amounts or participants.
  * zk-SNARK circuits are designed to minimize proof generation and verification overhead while ensuring non-interactivity for smooth UX.
* **Technical Details:**
  * Uses trusted setup ceremonies and cryptographic parameters aligned with established zk-SNARK libraries (e.g., libsnark, zkSync’s circuits).
  * Smart contracts verify zk-proofs on-chain to enforce privacy guarantees while maintaining auditability.

#### Multi-Signature Wallets and Threshold Signatures

* **Multi-Signature Wallets:**
  * Critical transactions require multiple independent signatures, reducing single-point-of-failure risk.
  * Supports configurable M-of-N schemes where M signatures out of N authorized keys are required for transaction execution.
* **Threshold Signatures:**
  * Employs advanced **threshold cryptography** schemes (e.g., Shamir’s Secret Sharing, Schnorr threshold signatures) enabling distributed signing without exposing individual private keys.
  * Facilitates secure wallet recovery, shared custody (corporate or group wallets), and delegation.

#### AI-Powered Fraud Detection Algorithms

* **Behavioral Analysis:**
  * Machine learning models continuously monitor user behavior patterns including transaction frequency, typical amounts, geolocation changes, and device fingerprints.
  * Anomalies trigger adaptive risk scores to flag suspicious activity in real time.
* **On-Chain Anomaly Detection:**
  * Monitors unusual blockchain transaction patterns such as rapid fund movements, mixing services interaction, or large-value transfers inconsistent with user history.
  * Leverages graph analysis and clustering algorithms to detect potential fraudulent schemes or compromised wallets.
* **Automated Response:**
  * Suspicious transactions can be temporarily blocked pending user verification or multi-factor approval.
  * Alerts notify users immediately via Telegram with actionable recommendations.

#### Compliance with Data Protection Regulations

* BlockGram complies with global data protection laws including **GDPR (General Data Protection Regulation)** and **CCPA (California Consumer Privacy Act):**
  * User data collection and processing are governed by explicit consent mechanisms integrated into onboarding flows.
  * Provides users with rights to access, rectify, and delete personal data stored off-chain.
  * Implements data minimization principles; blockchain data remains pseudonymous with only minimal personally identifiable information processed off-chain.
  * Employs robust audit trails and data encryption to ensure data integrity and confidentiality.