A–Z crypto + Confium terms

A threshold policy that combines a quorum count ("T-of-N") with diversity constraints on signer attributes (region, jurisdiction, role). Example: "5-of-9 directors from 3 distinct regions". Implemented in confium-attributes.

See also: Concept

A formal procedure for generating, distributing, or refreshing cryptographic key material. Ceremonies are typically logged and witnessed to ensure the key never existed in a single party's sole possession.

Cryptographic Message Syntax (RFC 5652). The IETF standard envelope for signed, enveloped, or authenticated data. Confium's confium-cms crate implements SignedData envelopes.

See also: Specs

A signature that bundles the artifacts of multiple algorithms (e.g. Ed25519 + ECDSA-P256 + ML-DSA-65). Verification succeeds only when every component verifies. Used for post-quantum migration and defense in depth.

See also: Concept · Use case

A Merkle tree proof (RFC 6962 §2.1.2) showing that tree head N+1 extends tree head N — the first N entries are identical. Makes split-view attacks detectable.

See also: Concept

The Confium service that orchestrates multi-party threshold sessions. Receives partial signatures from signers, aggregates them, and produces the final signature. Does not hold the secret; cannot produce signatures alone.

See also: Architecture

A threshold ECDSA protocol (Canetti, Makriyannis, Peled 2020). Three-round signing with a strong security model against malicious coordinators. Implemented in confium-tc-cmp20.

A TOML file describing a Confium deployment: signers, quorum policy, algorithm allow-lists, transparency log configuration. Loaded by Confium::Config::Manifest at boot.

In Mode 3 deployments, an authorized signer in the institutional quorum. Directors are typically the parties whose threshold participation is required to issue a certificate.

Elliptic Curve Integrated Encryption Scheme. A standard for public-key encryption using elliptic curves. Confium's confium-tc-ecies-p256 crate implements a threshold variant.

A public-key encryption scheme with homomorphic properties that make it amenable to threshold decryption. The confium-tc-elgamal-p256 crate implements threshold ElGamal over P-256.

Flexible Round-Optimized Schnorr Threshold signatures. A two-round threshold signing protocol optimized for Schnorr-based schemes (Ed25519, Schnorr-P256). Implemented in confium-tc-frost-ed25519 and confium-tc-frost-p256.

See also: Example

Gennaro and Goldfeder's 2018 threshold ECDSA protocol. The basis for many production threshold ECDSA deployments. Implemented in confium-tc-gg18.

Proactive share refresh (Herzberg et al. 1995). Periodically re-randomizes shares so that compromise of shares from different periods does not aggregate. Implemented in confium-tc-reshare.

A Merkle tree proof (RFC 6962 §2.1.1) demonstrating that a specific entry is in the log, without revealing anything else. ~log N hashes long.

See also: Concept

Java Cryptography Extension provider. The standard Java mechanism for plugging in alternative crypto backends. Confium's confium-jce-provider crate lets Java applications use threshold signing via standard JCE APIs.

The polynomial math underlying Shamir secret sharing recovery. Given T points on a degree T−1 polynomial, uniquely determines the polynomial and thus its value at x=0 (the secret).

See also: Concept

A binary tree of hashes where each leaf commits to a data record and each internal node commits to its children. The root hash commits to the entire dataset. Used in transparency logs (RFC 6962).

See also: Concept

Multi-party computation. A family of techniques letting multiple parties compute a function over their joint inputs without revealing those inputs. Threshold signing is one application of MPC.

An open standard (based on ISO 7816) for smartcard-based OpenPGP operations. YubiKey and Nitrokey are common hardware implementations. Confium's confium-store-openpgp-card backend integrates with these devices.

OpenSSL 3.0's plugin mechanism for alternative crypto backends. Confium's confium-openssl-provider crate lets existing OpenSSL consumers use threshold signing via standard EVP_PKEY APIs.

A protocol for anchoring arbitrary data in the Bitcoin blockchain, providing irrefutable time-stamped evidence that data existed at a specific time. Used as defense in depth for transparency log tree heads.

See also: Concept

The Cryptographic Token Interface Standard (RSA Laboratories). The standard API for HSMs and smartcards. Confium's confium-pkcs11-server lets existing PKCS#11 consumers use threshold signing unchanged.

The minimum number of parties (T) that must participate in a threshold operation. Express as T-of-N where N is the total number of authorized parties.

The process of changing the share distribution without changing the underlying secret. Used to add or remove signers, or to proactively refresh shares for security (Herzberg refresh). Implemented in confium-tc-reshare.

Certificate Transparency (B. Laurie, A. Langley, E. Käsper 2013). Defines the Merkle tree transparency log structure, inclusion proofs, and consistency proofs that Confium's confium-transparency crate implements.

See also: Concept

Adi Shamir's 1979 scheme for splitting a secret into N shares such that any T of them reconstruct the secret while any T−1 reveal nothing. Based on polynomial interpolation over a finite field.

See also: Concept

One of N pieces produced by Shamir secret sharing (or analogous protocols). A share alone reveals nothing about the secret; T shares reconstruct it.

Confium's Mode 3 deployment shape: institutional certificate infrastructure where no single party can be trusted. Institutions define their own certificate formats, delegation rules, archival cadence, and quorum composition.

See also: Mode 3 docs · Use case

A family of cryptographic techniques where multiple parties must cooperate to perform an operation (sign, decrypt), such that no subset smaller than the threshold can do so alone.

See also: Concept

An append-only public record (typically a Merkle tree) of every operation a system performs. Makes silent certificate issuance or unauthorized operations detectable. Confium's confium-transparency crate implements RFC 6962 semantics.

See also: Concept

XML Signature Syntax and Processing (W3C). The standard for XML-encoded digital signatures. Confium's confium-xmldsig crate implements XMLDSig with Exclusive C14N canonicalization.