// GLOSSARY -- BLOCKCHAIN & CRYPTO FUNDAMENTALS

What is Private Key?

1 min read Updated

A private key is a cryptographic secret — a large random number — that grants complete control over a blockchain address, enabling the holder to sign transactions and move associated funds.

WHY IT MATTERS

Private keys are the foundation of blockchain security. A 256-bit random number mathematically corresponds to a public address. Anyone who knows it can sign transactions — no other authentication, no password reset, no recovery.

This creates a fundamentally different security model. In banking, identity verification can recover access. In crypto, the private key is the identity.

For AI agents, private key management is the central security challenge. An agent needs to sign transactions, but giving it a raw private key means a compromised agent means a drained wallet.

HOW POLICYLAYER USES THIS

PolicyLayer eliminates the need for agents to hold private keys directly. Through session keys and delegated signing, agents get constrained transaction authority without raw key access — maintaining security while enabling autonomy.

FREQUENTLY ASKED QUESTIONS

How should private keys be stored?
In HSMs for institutions, hardware wallets for individuals, or encrypted keystores for applications. Never in plain text or environment variables.
Private vs public key relationship?
Mathematically linked via elliptic curve cryptography. The public key derives from the private key, but not vice versa. This asymmetry is what makes the system secure.
Can private keys be hacked?
Not through brute force — 2^256 possibilities makes this impossible. Keys are compromised through social engineering, malware, or poor storage practices.

FURTHER READING

Enforce policies on every tool call

Intercept is the open-source MCP proxy that enforces YAML policies on AI agent tool calls. No code changes needed.

npx -y @policylayer/intercept
github.com/policylayer/intercept →
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