`math/os2ip`

Purpose

Octet-String-to-Integer Primitive (RFC 8017 §4.2). Decodes a big-endian byte string into a non-negative bigint. Used by every RSA scheme to convert a modulus-sized byte payload back into the integer the modular operations expect.

Thin re-export of @suaveplan/crypto-utils's canonical implementation so the entire project agrees on encoding semantics.

Features

Always returns bigint, never number, so precision is preserved for any byte length.
Pure decoder; never throws.

Usage: Basic Example

import { os2ip } from "@suaveplan/crypto-rsa/math";

const value = os2ip(new Uint8Array([0, 0, 0, 255])); // 255n

Usage: Advanced Example

import { i2osp, modPow, os2ip } from "@suaveplan/crypto-rsa/math";

function privateOpRoundTrip(
    sigBytes: Uint8Array,
    e: bigint,
    n: bigint,
    modulusByteLength: number
): Uint8Array {
    const sigInt = os2ip(sigBytes);
    const recovered = modPow(sigInt, e, n);
    return i2osp(recovered, modulusByteLength);
}

API Reference

`os2ip(bytes: Uint8Array): bigint`

Returns the big-endian-decoded bigint. Empty input returns 0n.

Implementation Notes

The canonical implementation lives in @suaveplan/crypto-utils/bytes/os2ip/os2ip.ts. This re-export gives RSA consumers a path-local import mirroring RFC 8017 §4.2.

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math/os2ip