/**
 * RFC 7914 Scrypt KDF. Can be used to create a key from password and salt.
 * @module
 */
import { pbkdf2 } from "./pbkdf2.js";
import { sha256 } from "./sha2.js";
// prettier-ignore
import { anumber, asyncLoop, checkOpts, clean, rotl, swap32IfBE, u32 } from "./utils.js";
// The main Scrypt loop: uses Salsa extensively.
// Six versions of the function were tried, this is the fastest one.
// RFC 7914 §3 / §4 step 2 applies Salsa20/8 to one 16-word (64-byte) block
// after xor'ing two such blocks.
// The local `y*` snapshot keeps the xor input stable even when `out` aliases `prev` or `input`.
// prettier-ignore
function XorAndSalsa(prev, pi, input, ii, out, oi) {
    // Based on https://cr.yp.to/salsa20.html and RFC 7914's Salsa20/8 core.
    // Xor blocks
    let y00 = prev[pi++] ^ input[ii++], y01 = prev[pi++] ^ input[ii++];
    let y02 = prev[pi++] ^ input[ii++], y03 = prev[pi++] ^ input[ii++];
    let y04 = prev[pi++] ^ input[ii++], y05 = prev[pi++] ^ input[ii++];
    let y06 = prev[pi++] ^ input[ii++], y07 = prev[pi++] ^ input[ii++];
    let y08 = prev[pi++] ^ input[ii++], y09 = prev[pi++] ^ input[ii++];
    let y10 = prev[pi++] ^ input[ii++], y11 = prev[pi++] ^ input[ii++];
    let y12 = prev[pi++] ^ input[ii++], y13 = prev[pi++] ^ input[ii++];
    let y14 = prev[pi++] ^ input[ii++], y15 = prev[pi++] ^ input[ii++];
    // Save state to temporary variables (salsa)
    let x00 = y00, x01 = y01, x02 = y02, x03 = y03, x04 = y04, x05 = y05, x06 = y06, x07 = y07, x08 = y08, x09 = y09, x10 = y10, x11 = y11, x12 = y12, x13 = y13, x14 = y14, x15 = y15;
    // Main loop (salsa)
    for (let i = 0; i < 8; i += 2) {
        x04 ^= rotl(x00 + x12 | 0, 7);
        x08 ^= rotl(x04 + x00 | 0, 9);
        x12 ^= rotl(x08 + x04 | 0, 13);
        x00 ^= rotl(x12 + x08 | 0, 18);
        x09 ^= rotl(x05 + x01 | 0, 7);
        x13 ^= rotl(x09 + x05 | 0, 9);
        x01 ^= rotl(x13 + x09 | 0, 13);
        x05 ^= rotl(x01 + x13 | 0, 18);
        x14 ^= rotl(x10 + x06 | 0, 7);
        x02 ^= rotl(x14 + x10 | 0, 9);
        x06 ^= rotl(x02 + x14 | 0, 13);
        x10 ^= rotl(x06 + x02 | 0, 18);
        x03 ^= rotl(x15 + x11 | 0, 7);
        x07 ^= rotl(x03 + x15 | 0, 9);
        x11 ^= rotl(x07 + x03 | 0, 13);
        x15 ^= rotl(x11 + x07 | 0, 18);
        x01 ^= rotl(x00 + x03 | 0, 7);
        x02 ^= rotl(x01 + x00 | 0, 9);
        x03 ^= rotl(x02 + x01 | 0, 13);
        x00 ^= rotl(x03 + x02 | 0, 18);
        x06 ^= rotl(x05 + x04 | 0, 7);
        x07 ^= rotl(x06 + x05 | 0, 9);
        x04 ^= rotl(x07 + x06 | 0, 13);
        x05 ^= rotl(x04 + x07 | 0, 18);
        x11 ^= rotl(x10 + x09 | 0, 7);
        x08 ^= rotl(x11 + x10 | 0, 9);
        x09 ^= rotl(x08 + x11 | 0, 13);
        x10 ^= rotl(x09 + x08 | 0, 18);
        x12 ^= rotl(x15 + x14 | 0, 7);
        x13 ^= rotl(x12 + x15 | 0, 9);
        x14 ^= rotl(x13 + x12 | 0, 13);
        x15 ^= rotl(x14 + x13 | 0, 18);
    }
    // Write output (salsa)
    out[oi++] = (y00 + x00) | 0;
    out[oi++] = (y01 + x01) | 0;
    out[oi++] = (y02 + x02) | 0;
    out[oi++] = (y03 + x03) | 0;
    out[oi++] = (y04 + x04) | 0;
    out[oi++] = (y05 + x05) | 0;
    out[oi++] = (y06 + x06) | 0;
    out[oi++] = (y07 + x07) | 0;
    out[oi++] = (y08 + x08) | 0;
    out[oi++] = (y09 + x09) | 0;
    out[oi++] = (y10 + x10) | 0;
    out[oi++] = (y11 + x11) | 0;
    out[oi++] = (y12 + x12) | 0;
    out[oi++] = (y13 + x13) | 0;
    out[oi++] = (y14 + x14) | 0;
    out[oi++] = (y15 + x15) | 0;
}
function BlockMix(input, ii, out, oi, r) {
    // The block B is `r` 128-byte chunks, i.e. `2r` 16-word (64-byte) Salsa blocks.
    let head = oi + 0;
    let tail = oi + 16 * r;
    for (let i = 0; i < 16; i++)
        out[tail + i] = input[ii + (2 * r - 1) * 16 + i]; // X ← B[2r−1]
    for (let i = 0; i < r; i++, head += 16, ii += 16) {
        // RFC 7914 §4 step 3 outputs `Y[0], Y[2], ...` first, then `Y[1], Y[3], ...`;
        // `head` and `tail` lay out those even/odd halves in place.
        XorAndSalsa(out, tail, input, ii, out, head); // head[i] = Salsa(blockIn[2*i] ^ tail[i-1])
        if (i > 0)
            tail += 16; // First iteration overwrites tmp value in tail
        // tail[i] = Salsa(blockIn[2*i+1] ^ head[i])
        XorAndSalsa(out, head, input, (ii += 16), out, tail);
    }
}
// Common prologue and epilogue for sync/async functions
function scryptInit(password, salt, _opts) {
    // Maxmem - 1GB+1KB by default
    const opts = checkOpts({
        dkLen: 32,
        asyncTick: 10,
        maxmem: 1024 ** 3 + 1024,
    }, _opts);
    const { N, r, p, dkLen, asyncTick, maxmem, onProgress } = opts;
    anumber(N, 'N');
    anumber(r, 'r');
    anumber(p, 'p');
    anumber(dkLen, 'dkLen');
    anumber(asyncTick, 'asyncTick');
    anumber(maxmem, 'maxmem');
    if (onProgress !== undefined && typeof onProgress !== 'function')
        throw new Error('progressCb must be a function');
    const blockSize = 128 * r;
    const blockSize32 = blockSize / 4;
    // Max N is 2^32 (Integrify is 32-bit).
    // Real limit can be 2^22: some JS engines limit Uint8Array to 4GB.
    // Spec check `N >= 2^(blockSize / 8)` is not done for compat with popular libs,
    // which used incorrect r: 1, p: 8. Also, the check seems to be a spec error:
    // https://www.rfc-editor.org/errata_search.php?rfc=7914
    const pow32 = Math.pow(2, 32);
    if (N <= 1 || (N & (N - 1)) !== 0 || N > pow32)
        throw new Error('"N" expected a power of 2, and 2^1 <= N <= 2^32');
    if (p < 1 || p > ((pow32 - 1) * 32) / blockSize)
        throw new Error('"p" expected integer 1..((2^32 - 1) * 32) / (128 * r)');
    // RFC 7914 §2 defines `dkLen` as a positive integer.
    if (dkLen < 1 || dkLen > (pow32 - 1) * 32)
        throw new Error('"dkLen" expected integer 1..(2^32 - 1) * 32');
    // Include the shared `tmp` scratch block so `maxmem` matches noble's actual temporary allocation.
    // Node requires more headroom here, so this accounting is intentionally noble-specific.
    const memUsed = blockSize * (N + p + 1);
    if (memUsed > maxmem)
        throw new Error('"maxmem" limit was hit: memUsed(128*r*(N+p+1))=' + memUsed + ', maxmem=' + maxmem);
    // [B0...Bp−1] ← PBKDF2HMAC-SHA256(Passphrase, Salt, 1, blockSize*ParallelizationFactor)
    // Since it has only one iteration there is no reason to use async variant
    const B = pbkdf2(sha256, password, salt, { c: 1, dkLen: blockSize * p });
    const B32 = u32(B);
    // Re-used between parallel iterations. Array(iterations) of B
    const V = u32(new Uint8Array(blockSize * N));
    const tmp = u32(new Uint8Array(blockSize));
    let blockMixCb = () => { };
    if (onProgress) {
        const totalBlockMix = 2 * N * p;
        // Invoke callback if progress changes from 10.01 to 10.02
        // Allows to draw smooth progress bar on up to 8K screen
        const callbackPer = Math.max(Math.floor(totalBlockMix / 10000), 1);
        let blockMixCnt = 0;
        blockMixCb = () => {
            blockMixCnt++;
            if (onProgress && (!(blockMixCnt % callbackPer) || blockMixCnt === totalBlockMix))
                onProgress(blockMixCnt / totalBlockMix);
        };
    }
    return { N, r, p, dkLen, blockSize32, V, B32, B, tmp, blockMixCb, asyncTick };
}
function scryptOutput(password, dkLen, B, V, tmp) {
    // Shared final PBKDF2-and-cleanup step: keep the derived key, wipe the scrypt workspace.
    const res = pbkdf2(sha256, password, B, { c: 1, dkLen });
    clean(B, V, tmp);
    return res;
}
/**
 * Scrypt KDF from RFC 7914. See {@link ScryptOpts}.
 * @param password - password or key material to derive from;
 *   JS string inputs are UTF-8 encoded first
 * @param salt - unique salt bytes or string; JS string inputs are UTF-8 encoded first
 * @param opts - Scrypt cost and memory parameters. `dkLen`, if provided,
 *   must be `>= 1` per RFC 7914 §2. See {@link ScryptOpts}.
 * @returns Derived key bytes.
 * @throws If the Scrypt cost, memory, or callback options are invalid. {@link Error}
 * @example
 * Derive a key with scrypt.
 * ```ts
 * scrypt('password', 'salt', { N: 2**18, r: 8, p: 1, dkLen: 32 });
 * ```
 */
export function scrypt(password, salt, opts) {
    const { N, r, p, dkLen, blockSize32, V, B32, B, tmp, blockMixCb } = scryptInit(password, salt, opts);
    swap32IfBE(B32);
    for (let pi = 0; pi < p; pi++) {
        const Pi = blockSize32 * pi;
        for (let i = 0; i < blockSize32; i++)
            V[i] = B32[Pi + i]; // V[0] = B[i]
        for (let i = 0, pos = 0; i < N - 1; i++) {
            BlockMix(V, pos, V, (pos += blockSize32), r); // V[i] = BlockMix(V[i-1]);
            blockMixCb();
        }
        BlockMix(V, (N - 1) * blockSize32, B32, Pi, r); // Process last element
        blockMixCb();
        for (let i = 0; i < N; i++) {
            // First u32 of the last 64-byte block (u32 is LE)
            // RFC 7914 Integerify(X) uses the whole last 64-byte block, but mod N
            // only depends on the low word here because N is a power of two and
            // this implementation caps N at 2^32.
            // & (N - 1) is % N as N is a power of 2, N & (N - 1) = 0 is checked
            // above; >>> 0 for unsigned, input fits in u32.
            const j = (B32[Pi + blockSize32 - 16] & (N - 1)) >>> 0; // j = Integrify(X) % iterations
            // tmp = B ^ V[j]
            for (let k = 0; k < blockSize32; k++)
                tmp[k] = B32[Pi + k] ^ V[j * blockSize32 + k];
            BlockMix(tmp, 0, B32, Pi, r); // B = BlockMix(B ^ V[j])
            blockMixCb();
        }
    }
    swap32IfBE(B32);
    return scryptOutput(password, dkLen, B, V, tmp);
}
/**
 * Scrypt KDF from RFC 7914. Async version. See {@link ScryptOpts}.
 * @param password - password or key material to derive from;
 *   JS string inputs are UTF-8 encoded first
 * @param salt - unique salt bytes or string; JS string inputs are UTF-8 encoded first
 * @param opts - Scrypt cost and memory parameters. `dkLen`, if provided,
 *   must be `>= 1` per RFC 7914 §2. `asyncTick` is only a local
 *   scheduler-yield control for this JS wrapper, not part of RFC 7914.
 *   See {@link ScryptOpts}.
 * @returns Promise resolving to derived key bytes.
 * @throws If the Scrypt cost, memory, or callback options are invalid. {@link Error}
 * @example
 * Derive a key with scrypt asynchronously.
 * ```ts
 * await scryptAsync('password', 'salt', { N: 2**18, r: 8, p: 1, dkLen: 32 });
 * ```
 */
export async function scryptAsync(password, salt, opts) {
    const { N, r, p, dkLen, blockSize32, V, B32, B, tmp, blockMixCb, asyncTick } = scryptInit(password, salt, opts);
    swap32IfBE(B32);
    for (let pi = 0; pi < p; pi++) {
        const Pi = blockSize32 * pi;
        for (let i = 0; i < blockSize32; i++)
            V[i] = B32[Pi + i]; // V[0] = B[i]
        let pos = 0;
        await asyncLoop(N - 1, asyncTick, () => {
            BlockMix(V, pos, V, (pos += blockSize32), r); // V[i] = BlockMix(V[i-1]);
            blockMixCb();
        });
        BlockMix(V, (N - 1) * blockSize32, B32, Pi, r); // Process last element
        blockMixCb();
        await asyncLoop(N, asyncTick, () => {
            // First u32 of the last 64-byte block (u32 is LE)
            // RFC 7914 Integerify(X) uses the whole last 64-byte block, but mod N
            // only depends on the low word here because N is a power of two and
            // this implementation caps N at 2^32.
            // & (N - 1) is % N as N is a power of 2, N & (N - 1) = 0 is checked
            // above; >>> 0 for unsigned, input fits in u32.
            const j = (B32[Pi + blockSize32 - 16] & (N - 1)) >>> 0; // j = Integrify(X) % iterations
            // tmp = B ^ V[j]
            for (let k = 0; k < blockSize32; k++)
                tmp[k] = B32[Pi + k] ^ V[j * blockSize32 + k];
            BlockMix(tmp, 0, B32, Pi, r); // B = BlockMix(B ^ V[j])
            blockMixCb();
        });
    }
    swap32IfBE(B32);
    return scryptOutput(password, dkLen, B, V, tmp);
}
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